Summary Table

Logic to selecting the top 18 abstracts:

  • Divisional Picks were selected first.
  • Top Domains were selected next (excluding medical students). In some instances the divisional pick was the top from a domain, so then the second in the domain was selected.
  • Top from Divisions were selected next (excluding medical students). In some instances the divisional pick and top domain were already included, so then the second or third place from that division was selected.
  • The next highest 6 were then selected and included medical student presentations.
ABS IDDivDom# Rev'sScoreRank2Comments to Committee
AB01: Relative Effectiveness of the Various Surgical Treatment Options for Distal Radius Fractures: Systematic Review and Network Meta-analysis of Randomized Controlled TrialsOrtCli386.462no DoS surg author; Well done network metaanalysis and enjoyed reading it. Despite statistically significant findings, not sure if this translates into meaningful differences clinically in light of an MCID of >10 using DASH score. Robustness of findings not mentioned in the abstract- heterogeneity of study populations and plausibility of transivity which may be an issue given high number of unique procedures (9). not addressed in the abstract.
AB02: Angiographic metrics of perfusionVasCli358.5429med student; Uncertain if impact is sufficient - I have no reservations about the study.; poster vs. reject. Both the outcome measure ("analyzing existing angiographic technology from a unique perspective") and the exposure ("additional physiologic information" are vaguely defined
AB03: Intraoperative simultaneous limb perfusion monitoring (INSTANT) studyVasCli388.961
AB04: Association Between Attempted Arteriovenous Fistula Creation and Mortality in Patients Starting Hemodialysis via a Catheter: A Multicenter, Canadian, Retrospective Cohort StudyVasCli272.1911see comments to authors; I'm not opposed to presentation, but this seems so odd to me
AB05: Does Post-Operative Insulin Management Make a Difference for Non-Diabetic Arthroplasty Patients with an Elevated Pre-Operative Hemoglobin A1C?OrtQua249.0632med student; Large cohort study but did not explain well of how variables were identified and controlled. The relative contribution of controlling glucose in a logistic regression model not mentioned. Weakly substantiated conclusion of using insulin in all non-diabetics with high A1c despite a non-significant, and relatively small absolute difference in comparison group. Mention of resource utilization and cost is an important factor not mentioned.; reject vs poster. methods are not clear, and results are not clearly reported. multiple risk factors for SSI are identified (but how ? there is no multivriate regression, and a single RR is reported.) Conclusion and results are at odds. ; there is no multivariate adjustment shown. there is no statistically significant difference between the insulin treated and non insulin treated group, and yet the authors conclude there is a difference. the authors identify 3 subgroups with increased risk of SSI, but a single RR is give for all three.
AB07: Preoperative left ventricular end-systolic dimension predicts occurrence of aortic insufficiency following aortic valve-preservation and repair surgeryCarCli274.6910
AB08: Unexplained Fever following Thoracic Aortic Repair with Woven Dacron Grafts CarCli350.6331Case report only; Very interesting and important but only 2 cases and no additional data to confirm that the graft was responsible. How many other individuals have this graft and no fever?; Essentially this abstract represents a small case series report of two .While this case review may be publishable as a case report and could be a starting point for further investigation in the future in its current form it is not likely suitable for Collin's Day.; If there were poster sessions, this could be a poster but the impact is insufficient for a podium
AB10: The Standardization of Post-operative Analgesic Prescriptions to Reduce Opioid Use in Outpatient Spine Surgical Procedures OrtQua366.8818Good QI initiative
AB11: Can Cup Orientation Achieved with a Posterior Approach Ever Be as Reliable as That Achieved with an Anterior Approach?OrtCli363.9622
AB12: Impact of Revascularization Strategy on Left Ventricular Ejection Fraction Recovery in Patients with Coronary Artery Disease and Severely Reduced Ejection FractionCarCli370.4216
AB13: Implementation of ‘CODE AAA’ expedites management of patients with ruptured abdominal aortic aneurysmVasQua375.639med student
AB15: Revascularization versus best medical therapy for the management of asymptomatic carotid artery stenosis in females: a systematic review and meta-analysisVasCli382.294Important clinical question reviewed with appropriate methodology; N/A; If there were poster sessions, this could be a poster but the impact is insufficient for a podium
AB16: Comparison of bilateral internal thoracic artery bypass grafting configurations: composite versus in situ graftingCarCli365.4220If there were poster sessions, this could be a poster but the impact is insufficient for a podium
AB18: Pedicle Screw Instrumentation in Scoliosis Surgery: On Site Simulation Data on Accuracy and Efficiency With Different TechniquesOrtEdu36027no DoS surg author; There is no outcome measure of the learning of the fellow, there is no mention of their experience, I am confused by the inclusion of a learning outcome. I don't know what on site simulation is; It seems as though simulation was added in as a last thought. The study is largely clinical, assessing different surgical techniques, just using a simulated environment. It does not add anything to simulation or education literature.; There is no hypothesis in the abstract. I am not sure of the dilemma they are trying to solve or the relevance of the paper to this field; The way the abstract was written was strange so inquired with Jenn as to who the authors were and discovered the PI is from Calgary and only UO representation is resident as third author
AB19: Comparison of non-operative versus operative management of resectable colorectal cancer in elderly patients: a systematic review GenCli277.196Not surprising results
AB20: Competency-Based Resident Evaluations: Neurosurgical Faculty Perspectives On Feasibility NeuEdu358.9628It has very limited impact. It is documenting something we could have suspected. Not a lot of information on what is currently happening
AB23: Evolution of outcome and process-of-care measures during Enhanced Recovery After Thoracic SurgeryThoQua264.6921med student
AB25: Is intraoperative frozen section analysis of margins and re-resection of positive margins beneficial in patients undergoing resection of hilar cholangiocarcinoma? A systematic review and meta-analysisGenCli367.3417Poster; Poster
AB26: Measuring Cost of Adverse Events Following Thoracic Surgery: A Systematic ReviewThoCli363.5423
AB27: Division wide implementation of an Enhanced Recovery After Thoracic Surgery (ERATS) program – longitudinal impact on postoperative outcomes, processes of care, patient satisfaction and quality of lifeThoCli370.8314
AB28: Outcomes of abiraterone plus prednisone versus docetaxel in metastatic hormone-sensitive prostate cancer in a real-world settingUroCli366.8818poster or podium. there does not appear to be any multivariate adjustment in this observational comparison of two different treatments. a multivariate cox regression for example may be useful to adjust for confounders. The authors give us p values, but not the actual observed median survivals in both treatment arms, which would be very useful and probably more clinically telling than a simple p value.
AB29: A chance for reform: the environmental impact of travel for general surgery residency interviewsGenEdu361.8825maybe as a poster
AB30: Targeting CD155 Poliovirus Receptor: A Novel Strategy to Prevent Postoperative Immunosuppression in Cancer Patients GenTra385.423N/A
AB33: Understanding breast cancer laterality to improve treatment and training in General SurgeryGenCli346.4133no DoS surg author (med student); This research question can not be answered using this small smple size
AB34: Assessing self-awareness in general surgery applicants: an insight into interview performanceGenEdu370.6315
AB35: Post-prostatectomy adjuvant androgen deprivation therapy— current opinions and practices of Canadian urologistsUroCli276.257Very simple study; perhaps more labor intensive studies should be presented at Collins Day
AB36: Association between radical cystectomy prophylactic antibiotic regimen and post-operative infectionUroCli271.2513Would have liked to have more details on the univariate and multivariate analysis in the results; what factors predicted or were associuated with infection?
AB37: A renal tumour prediction tool using the Canadian Kidney Cancer Information SystemUroCli378.545yes - top Uro (med student); none
AB38: A retrospective cohort study of patients undergoing elective bowel resection before and after implementation of an anemia screening and treatment initiative. GenQua462.9724The QI process wasn't described and then it is not mentioned how many patients were in the post implementation. nothing noted about adherence to implementation. cost analysis si very tricky to determine accurate in the present system and it does not explained what was included into it (Or time, etc); the first objective wasnt described in the abstract.; Before and after study looking at costs and outcomes, objectives did not match the data presented, weak statistical methodology, showed correlation not causation
AB40: A systematic review and meta-analysis of randomized controlled trials comparing intraoperative red blood cell transfusion strategiesGenCli275.948N/A
AB41: The gap in urology resident understanding of a robotic prostatectomy and what residents do not perceive when assistingUroEdu260.9426low impact- suggests that staff and residents have different understanding in procedures...seems obvious
AB43: The Effect of Immediate Breast Reconstruction on Adjuvant Therapy Delay, Locoregional Recurrence and Disease-Free SurvivalPlaCli371.8812yes - top Pla (med student)
AB44: Measuring surgeon empathy: implementation, results and validity of the CARE measure survey from a trans-departmental initiativePlaQua357.9230no

AB01

Relative Effectiveness of the Various Surgical Treatment Options for Distal Radius Fractures: Systematic Review and Network Meta-analysis of Randomized Controlled Trials

Background Many treatment options exist for distal radius fractures (DRFs); however, a simultaneous comparison of all methods is difficult using conventional study designs. Therefore, we performed a network meta-analysis of randomized controlled trials. Included studies were RCTs assessing surgical treatment for adult patients with displaced DRFs. Seventy RCTs (4789 patients) were included. Nine different treatments were included. Subgroup analyses were conducted for intraarticular fractures, extraarticular fractures, and patients with an average age greater than 60 years. Outcomes were 1-year DASH score, total complications, and complications requiring reoperation. Bayesian methodology with random-effects models was used. Rank orders were generated using surface under the cumulative ranking curve values. Results Volar plating was ranked the highest for DASH score at 1 year (mean difference -7.34 [95% credible interval -11 to -3.7], MCID = 10). Only locked volar plating was favored over nonoperative treatment for patients older than 60 years of age (MD -6.4 [-11 to -2.1]) and for those with intraarticular fractures (MD -8.4 [-15 to -2.0]). Among all patients, intramedullary fixation (odds ratio 0.09 [0.02 to 0.84]) and locked volar plating (OR 0.14 [0.05 to 0.39]) were associated with a lower complication risk compared with nonoperative treatment. For intraarticular fractures, volar plating was the only treatment associated with a lower risk of complications than nonoperative treatment (OR 0.021 [< 0.01 to 0.50]). Among all patients, the risk of complications requiring operation was lower with intramedullary fixation (OR 0.06 [< 0.01 to 0.85) than with nonoperative treatment. Conclusions No clinically important differences favored any surgical treatment option with respect to functional outcome. Volar plating was associated with a lower complication risk, particularly in patients with intraarticular fractures. For patients older than 60 years of age, nonoperative treatment may still be the preferred option because there is no reliable evidence showing a consistent decrease in complications with operative treatment.

AB02

Angiographic metrics of perfusion

INTRODUCTION: Angiograms for peripheral vascular disease can provide physiologic information about blood flow in addition to the more common use as an anatomic assessment of stenosis. The objective of this study is to determine if analyzing existing angiographic technology from a unique perspective can provide additional physiologic data to the operator. METHODS: We performed a post-hoc analysis of a prospectively enrolled cohort study by measuring the contrast density at consistent regions upstream and downstream of a single atherosclerotic peripheral vascular lesion, in each frame of the pre- and post-treatment angiographic videos. Static perfusion metrics (Density Ratio and Peak Gradient) and dynamic perfusion metrics (Peak Density, Wash-In and Wash-Out Rates) were derived pre-and post-treatment from static angiogram images and corresponding Time Attenuation Curves. The mean differences of the pre-and post-treatment metrics were compared with a paired T-test. RESULTS: We analyzed 253 angiographic image frames of the pre-treatment and completion angiograms of 26 unique procedures. 3 (12%) of procedures involved an iliac artery, 18 (69%) involved a femoropopliteal artery, and 5 (19%) involved a tibial artery. All included patients had complete resolution of symptoms and ABI increase > 0.15 postoperatively. The composite rates of distal Wash-In (MD 1.25; 95% CI [0.32,2.19]; p=0.011) and Wash-Out (MD -1.21; 95% CI [-2.02,-0.40]; p=0.005) metrics showed significant improvement following successful revascularization. Conversely, the proximal Wash-In and Wash-Out Rates, Peak Static Gradient, Density Ratio, and Peak Density did not significantly change (p>0.05). CONCLUSION: Angiographic assessment of perfusion is a convenient method which leverages existing operating room infrastructure. This study demonstrates that while static metrics may be prone to error, the derivative of contrast intensity over time can provide objective feedback of perfusion to guide endovascular revascularization.

AB03

Intraoperative simultaneous limb perfusion monitoring (INSTANT) study

INTRODUCTION: We propose the application of real-time physiologic perfusion monitoring into the operating room to guide intraoperative decision making during endovascular procedures for atherosclerotic peripheral vascular disease (PVD). The primary objective is to determine if the magnitude of change of intraoperative toe-brachial index (TBI) during these procedures is associated with major adverse limb events (MALE) within 1 year post-procedure. METHODS: We performed a prospective, operator-blinded and blinded endpoint-adjudicated observational cohort study. The TBI was serially assessed at multiple time points before, during, and after endovascular procedures for symptomatic PVD. The association between intraoperative change in TBI and postoperative outcomes were analyzed with Cox Proportional Hazards, accounting for clustering of legs within subjects and the competing risk of mortality, and adjusted for baseline clinical status of limb ischemia and vascular level of intervention. The ideal threshold of intraoperative TBI improvement to predict freedom from MALE was calculated to maximize sensitivity and specificity. This study is registered on ClinicalTrials.gov (NTC 03875846) and a-priori protocol is published (BMJ Open 2019;9:e030456). RESULTS: 80 limbs of 67 patients were enrolled. Intraoperative TBI measurements with intra-arterial sheaths in-situ were feasible and reliably correlated with outpatient measurements (r=0.74 p<0.01, ICC=0.78). During one year follow-up, MALE occurred in 21% of limbs. The magnitude of change in the intraoperative TBI measurements before and after intervention was strongly associated with clinical outcomes such as MALE (Adj HR = 0.19 [95% CI 0.07 – 0.49], p < 0.01, per change in TBI of 0.1). The ideal threshold of improvement in intraoperative TBI is 0.08 (Positive LR = 2.14, Negative LR = 0.20). CONCLUSION: Intraoperative TBI assessment during endovascular procedures for PVD is reliable and strongly correlated with tangible postoperative clinical outcomes such as MALE. These findings suggest that intraoperative perfusion assessment may be a promising tool to guide intraoperative decision making.

AB04

Association Between Attempted Arteriovenous Fistula Creation and Mortality in Patients Starting Hemodialysis via a Catheter: A Multicenter, Canadian, Retrospective Cohort Study

Objective: To examine the association between attempted arteriovenous fistula (AVF) creation in patients already receiving hemodialysis via a central venous catheter (CVC) and mortality. We hypothesized that attempting AVF creation in these patients would be associated with a lower mortality, regardless of whether the AVF later became usable. Methods: We included patients aged 18-years and older who initiated hemodialysis via a CVC at one of five dialysis programs in Ontario, Manitoba, and Alberta between January 1, 2004 and May 31, 2012 and did not receive a previous attempt at AVF creation. We used a marginal structural model to determine the association between attempted AVF creation and death after accounting for confounding and immortal-time bias (the period of follow-up during which death cannot occur because of the study design). Results: In total, 3,145 patients started hemodialysis during the study period, and 61% did so via CVC. Of the 1,832 who had no pre-dialysis AVF creation attempt, 565 (31%) underwent a subsequent attempt at AVF creation. Those who underwent an attempt at AVF creation were younger, had fewer comorbidities and a lower glomerular filtration rate, less often started dialysis as an inpatient, and more often received pre-dialysis care. In a marginal structural model controlling for differences in age, gender, duration of pre-dialysis care, and a history of diabetes or cardiovascular disease, attempted AVF creation was associated with a significantly lower mortality [hazard ratio=0.53; 95% confidence interval=0.43-0.65]. This effect did not appear to be mediated by differences in the frequency of hospitalizations or subsequent procedures and remained robust in sensitivity analyses accounting for differences in between-group follow-up. Conclusion: In this multicenter, Canadian, retrospective cohort study, although most included patients initiated hemodialysis via CVC, those who underwent a subsequent attempted AVF creation had a significantly reduced mortality.

AB05

Does Post-Operative Insulin Management Make a Difference for Non-Diabetic Arthroplasty Patients with an Elevated Pre-Operative Hemoglobin A1C?

Introduction: Dysglycemia in the post-operative period has been associated with increased rates of infection following total joint arthroplasty. Patients without the clinical diagnosis of diabetes with hemoglobin A1C% values of 5.7% and above have been shown to be dysglycemic in the peri-operative period. This study examines the risk of infection for patients undergoing total joint arthroplasty. Methods: Retrospective review of prospectively collected data, for all primary, elective total hip and knee arthroplasties performed at TOH between April 2010 and October 2018. In total, 5,754 primary total joints were performed. There were 2,083 non-diabetic patients with hemoglobin A1c of 5.7% or higher. Patients received insulin management or no insulin according to the treatment decision of the attending surgeon. Results: “Non-diabetic” patients with HbA1c 5.7% or higher treated with insulin had an infection rate of 0.51%. Those who did not receive insulin had an infection rate of 1.0 % (p=0.22). Patients with age 60 or above, ASA 3 and higher and BMI 24 or higher had a higher infection rate (p 0.020, RR 8.0) if insulin management was not used following surgery. Conclusion: Patient with undiagnosed perioperative dysglycemia who received post-operative insulin had a lower infection rate than those patients who did not. Two sub-groups clearly benefited from post-operative insulin management. Consideration should be given for post-operative glucose management in all clinically non-diabetic patients with hemoglobin A1C of 5.7% or higher.

AB07

Preoperative left ventricular end-systolic dimension predicts occurrence of aortic insufficiency following aortic valve-preservation and repair surgery

Introduction: Preoperative left ventricular end-systolic dimension (LVESD) ≥5.0 cm is a class IIa indication for surgical intervention for aortic insufficiency (AI); however, the effect of LV dilatation on the longevity of the aortic valve has not been investigated. This study aims to assess the impact of pre-operative LV dimension on the long-term outcome of aortic valve preservation surgery. Methods: From 2009 to 2019, 256 patients underwent aortic valve preservation surgery at a single center. Median follow-up was 5 years. The primary outcome was the development of >1+ AI at 6-years; secondary outcomes include long-term mortality, freedom from >2+ AI, and freedom from aortic valve re-operation. Cox-proportional hazard analysis was performed to identify predictors of aortic valve deterioration. Results: In-hospital mortality was 0.8% and survival at 8 years was 85.5% ± 3.4%. Freedom from >1+ AI at 6-years was 71.1 ± 3.4% %. Patients with pre-operative indexed LVESD (LVESDi) ≥2.0 cm/m2 had higher risk of developing >1+ AI at 6-years compared to patients with pre-operative LVESDi of 1.5-1.9 cm/m2 and ≤1.4 cm/m2 (50.3% ± 0.1% vs. 80.9 ± 0.1% vs. 92.2± 0.1%, respectively) (p < 0.01). On risk-adjusted multivariable analysis, pre-operative LVESDi was an independent predictor for recurrence of >1+ AI (HR 2.2; C.I. 1.5–3.4). Conclusions: Higher preoperative LVESDi ≥2 cm/m2 increases risk of recurrent >1+ AI following aortic valve preservation surgery. Further investigation in the appropriate operative threshold for AI may be warranted.

AB08

Unexplained Fever following Thoracic Aortic Repair with Woven Dacron Grafts

INTRODUCTION: Transient fever is not uncommon post-cardiac surgery, usually related to underlying clinical process such as infection or inflammation. The presence of fever may lead to extensive investigation, resulting in prolonged hospitalizations and higher resource utilization. Here, we present two cases of acute aortic dissection with prolonged fever of unknown origin(FUO) persisting months after aortic repair with woven Dacron grafts. METHODS: Charts were reviewed for a series of two patients, post-aortic dissection repair with Gelweave woven graft who persisted to have cyclical fevers of unknown origin. Daily oral temperature measurements and white blood cell counts (WBC) were collected. RESULTS: Patients had persistent fevers and leukocytosis ranging unit post-operative day 20. C-reactive protein (CRP) levels ranged from 64-100 mg/mL (normal <10 mg/mL) and ESR ranged from 24-40 mm/h (normal <6 mm/h). Complete infectious workup was negative. There was no evidence of autoimmune disease, thromboembolism, drug reaction or malignancy. CT scan demonstrated large perigraft collection in both cases, which was confirmed to be sterile by re-sternotomy with negative cultures. WBC- single photon emission computed tomography (SPECT) and WBC fluorodeoxyglucose (FDG)-positron emission tomography(PET) scan was performed in both patient 1 and 2 respectively ruling out infectious uptake of surgical site. CONLUSIONS: We describe a systemic inflammatory syndrome associated post-aortic repair with Gelweave graft with fevers persisting several months after surgery. Both patients had prolonged hospital admissions and extensive investigations that did not yield an underlying cause for the fevers, emphasizing the importance of recognition and further characterization of this clinical syndrome.

AB10

The Standardization of Post-operative Analgesic Prescriptions to Reduce Opioid Use in Outpatient Spine Surgical Procedures

Introduction Reconciling adequate pain control peri-operatively while mitigating the side effects related to prescription opioid analgesia is pivotal to successful surgical outcomes. Prescribing opioids upon discharge after day surgery is common practice, however there are many inherent risks including dependency, diversion and medical complications. Our study investigates the effect of a standardized analgesic prescription on the amount of opioids prescribed and patients’ pain control in the early post-operative period. Methods With the implementation of a new electronic medical record (EPIC), a standardized prescription was built employing multi-modal analgesia and a stepwise approach to analgesics based on level of pain. Additionally, a patient education handout was developed and provided to patients to explain the prescription. Four months of consecutive patients undergoing elective spine surgery as a day case or overnight stay prior to Epic implementation were compared to a similar cohort who received the standardized prescription and education. Patient satisfaction with pain control in the early post-operative period, refills required, and opioids prescribed in morphine equivalents were compared before and after the introduction of the standardized analgesic prescription. Results Twenty-six patients received usual care and 26 patients the standardized prescription and education handout. There was no difference between groups in patient satisfaction or number of refills required. There was a significant difference in the amount of opioids prescribed pre- and post-intervention. Conclusion This study demonstrates that a standardized prescription consisting of an appropriate amount of analgesics is effective in reducing the amount of opioids prescribed post-operatively in elective spine surgery day surgery and overnight stay procedures without decreasing patient satisfaction or increasing the number of refills required.

AB11

Can Cup Orientation Achieved with a Posterior Approach Ever Be as Reliable as That Achieved with an Anterior Approach?

Introduction: Radiographic cup orientation is influenced by pelvic position and operative cup orientation at impaction. Pelvic position is more reliable in the anterior approach (AA) leading to superior cup orientations. Whether the use of contemporary techniques (3-point pelvic supports and digital inclinometer) when performing a posterior approach (PA) is associated with equal ability to achieve the desired cup orientation is unknown. The aim of this study was to compare cup orientations achieved (1) with AA between 2 surgeons and (2) with 2 approaches [AA and PA (using contemporary techniques)] by one of these surgeons. Patients and Methods: 189 total hip replacements (THA) were prospectively studied; 117 were AA-THA by 2 surgeons (A:67; B:50). Surgeon A also performed 72 PA-THA; a 3-point support positioner and an inclinometer were used to ensure that intra-operative inclination was <40˚. Cup inclination/anteversion was measured from post-operative radiographs. Optimum inclination/anteversion was defined as 40°/20° (±10°). Results: Equivalent cup inclination (A: 39°; B: 38°; p=0.28) and anteversion (A: 21°; B: 21°; p=0.98) were achieved by both surgeons with the AA. There was no difference in the ability to achieve target orientation between the 2 groups (A:81%; B:70%; p= 0.20). When comparing AA and PA for Surgeon A, similar inclinations (AA: 39°; PA: 39°; p= 0.60) and anteversions (AA: 21°; PA: 21°; p= 0.82) were achieved. Both approaches showed no difference in the achieved cup orientation target (AA: 81%; PA: 79%; p=0.83). Discussion: By comparing the orientations achieved by 2 surgeons with an AA, we established the greatest possibility to achieve the desired cup orientation without navigation. This study illustrates that similar cup orientations to those achieved with an AA, can be achieved with a PA using contemporary techniques that allow for better control of pelvic position and accurate measure of intra-operative inclination.

AB12

Impact of Revascularization Strategy on Left Ventricular Ejection Fraction Recovery in Patients with Coronary Artery Disease and Severely Reduced Ejection Fraction

INTRODUCTION: Randomized studies of PCI vs CABG have typically excluded patients with reduced LVEF, and the impact of revascularization strategy on LVEF recovery in these patients is unclear. We sought to examine whether the incidence of LVEF recovery (defined as ≥ 10% increase in LVEF post revascularization) would differ in patients who underwent PCI vs CABG. METHODS: Included in this retrospective cohort study were adult patients with stable CAD and LVEF  35%, who underwent elective CABG or PCI at a tertiary center between Jan 2007 – Dec 2017. Temporal trends in the maximum change in LVEF were examined using linear regression. RESULTS: There were 205 CABG patients and 55 PCI patients with LVEF measurements post revascularization. Follow-up beyond 3 months was available for 40% in each group. Groups were similar with respect to sex. CABG patients were more likely to have carotid disease (14% vs 1%; p<0.01) and diabetes (58% vs 38%; p<0.01). PCI patients were more likely to be on ASA (100% vs 90%; p=0.04), statin (97% vs 80%; p<0.01), ACEi/ARB (93% vs 57%; p<0.001) and MCRA agents (16% vs 5%; p<0.01), with similar rates of beta-blockade. LVEF recovery occurred in 57% of CABG patients and 50% of PCI patients (p=0.29). CABG patients exhibited ongoing improvement in LVEF over time and the rate of improvement was greater in CABG patients (Figure 1). CONCLUSIONS: In patients with reduced LVEF, we observed a similar frequency of LVEF recovery in those who underwent CABG as compared to PCI, with a tendency towards later LVEF recovery following CABG. Further long term prospective studies and are needed to confirm our findings, and to determine the best revascularization strategy in this population.

AB13

Implementation of ‘CODE AAA’ expedites management of patients with ruptured abdominal aortic aneurysm

INTRODUCTION: Delay of definitive surgical management has been identified as a predictor of death in ruptured abdominal aortic aneurysm (RAAA) patients. This project aims to determine the impact of a hospital-wide code protocol on processing times for patients with RAAA in order to mitigate this delay. METHODS: This cohort study included patients presenting with suspected or confirmed RAAA, before and after the implementation of a hospital-wide code protocol. Demographic, clinical, and time variable data (medians [IQRs]) were collected, including times to physician assessment, imaging and transfer to OR. RESULTS: A total of 51 patients with RAAA were identified in 2 separate time periods before and after implementation of CODE AAA (2013-2015 (n=35), 2019-2020 (n=16)). Patients in both groups were similar with respect to age, gender, proportion of inter-hospital transfers (74% vs. 75 %), and hemodynamic stability (minimum MAP 83 vs. 69 mmHg). A significant reduction in all median time intervals was observed after (vs. before) implementation of CODE AAA, including time to initial physician assessment (1.5 [4.75] vs. 10.5 [52.8] mins), time to vascular assessment (1.5 [6.25] vs. 21 [158] mins), time to imaging (13 [27] vs. 35 [97] mins) and time to OR (27 [50] vs. 56 [146.3] mins). The protocol was especially effective in expediting care for the subset of patients presenting to our ER without a previously known diagnosis of RAAA. Thirty-day mortality was paradoxically higher for patients presenting after implementation of CODE AAA (18% vs. 36%). CONCLUSION: The implementation of a hospital-wide RAAA code protocol expedited the time to physician assessment, imaging and intervention, but was not associated with improved mortality. This likely reflects an improved ability to provide expedited care to the most vulnerable population of RAAA patients that would most benefit from this protocol. Given the importance of rapid diagnosis and prompt mobilization of a multidisciplinary team for definitive management, a code protocol should be considered for centers providing care for RAAA patients.

AB15

Revascularization versus best medical therapy for the management of asymptomatic carotid artery stenosis in females: a systematic review and meta-analysis

INTRODUCTION: The purpose of this study is to review the evidence for revascularization (carotid endarterectomy [CEA] or carotid artery stenting [CAS]) and best medical therapy (BMT) with respect to perioperative and long-term rates of stroke and death in females with asymptomatic >60% carotid stenosis. METHODS: We systematically reviewed MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials for randomized controlled trials comparing CEA, CAS, and/or BMT in patients with asymptomatic carotid stenosis. Four reviewers identified and extracted data in duplicate from trials that met inclusion criteria. Authors were contacted to obtain unpublished sex-stratified data. Risk of bias was assessed using the Cochrane risk of bias assessment tool. We performed meta-analyses using a random effects model to evaluate perioperative and long-term rates of stroke and death associated with revascularization vs. BMT, and conducted subgroup analyses by revascularization method. Treatment effect was measured using odds ratio (OR) or risk difference (RD) with 95% confidence intervals (CI). This review was registered with PROSPERO. RESULTS: We reviewed 1323 abstracts and identified four randomized controlled trials that met inclusion criteria, reporting on a total of 2182 females. Revascularization significantly increased the risk of perioperative stroke and death as compared to BMT in females with asymptomatic carotid stenosis (RD 3% [95% CI 0.01, 0.04]), and demonstrated no benefit over BMT with respect to long-term stroke and death rates (OR 0.91 [95% CI 0.61, 1.37]). When stratified by type of revascularization, CEA modestly increased perioperative risk of stroke and death compared to BMT (RD 3% [95% CI 0.01, 0.04]). There was no difference in risk of perioperative stroke or death between CEA vs. CAS or CAS vs. BMT, and no difference in long-term stroke or death rates between CEA vs. BMT, CEA vs. CAS, or CAS vs. BMT (p<0.05 for each). CONCLUSIONS: Revascularization for the treatment of asymptomatic carotid stenosis in females conferred no benefit over BMT with respect to long-term rates of stroke and death, and modestly increased perioperative stroke and death risk.

AB16

Comparison of bilateral internal thoracic artery bypass grafting configurations: composite versus in situ grafting

Background: Multiple arterial grafting provides long-term benefits in graft patency and mortality. Studies suggest that a composite configuration of bilateral internal thoracic arteries (BITA) may have long-term benefits compared to in situ configuration grafting, including improved mortality and decreased revascularization. We sought to compare the clinical outcomes in composite versus in situ BITA configurations for coronary artery bypass grafting (CABG). Methods: We performed a retrospective cohort study in patients undergoing CABG with BITA at a single institution from January 2014 to June 2017. Two hundred and ninety (n=290) patients underwent CABG with BITA via composite (n=145) or in situ (n=145) configurations. The primary endpoint was 30-day mortality. Secondary endpoints were mortality, stroke, myocardial infarction, re-operation and revascularization after 30-days. We also evaluated the incidence of perioperative sternal wound infection, respiratory insufficiency, renal insufficiency, and blood transfusions. The number of total and arterial distal anastomoses were also compared between the groups. Results: There was no difference in the primary endpoint (30-day mortality) between the composite and in situ groups. Similarly, there was no difference in the secondary endpoints of mid-term mortality, stroke, myocardial infarction, re-operation, or revascularization. The frequency of >3 distal anastomoses for both arterial and total distal anastomoses were higher in the composite grafting group. The composite configuration featured more LITA to LAD anastomoses (98.6% vs. 33.1%;p<0.001) and the in situ configuration featured more RITA to LAD anastomoses 66.9% vs. 0.7%;p<0.001). The radial artery was used more commonly as a third conduit in the in situ group (43.4% vs. 27.6%;p=0.007). Conclusion: We conclude that the composite configuration is as safe as the in situ configuration for BITA usage in CABG. However, the composite configuration seems to afford more total and arterial distal anastomoses with less total number of conduits. The long-term differences have yet to be seen.

AB18

Pedicle Screw Instrumentation in Scoliosis Surgery: On Site Simulation Data on Accuracy and Efficiency With Different Techniques

Study design: Prospective experimental study with on-site simulation. Objective: To compare the accuracy and efficiency of different techniques for pedicle screw instrumentation (PSI). Summary of background data: Improving the safety and efficiency of PSI is a critical step to reduce the complication rates and the cost of scoliosis surgery. Innovative operative techniques for PSI have shown to safely improve efficiency, thereby reducing cost. Surgical simulation is a valuable tool to study different operative techniques. Methods: Five spine fellows instrumented 20 simulation models of a scoliotic spine with 10 pedicle screws per model. Four techniques were studied, including the conventional pedicle probe and the innovative sequential drilling technique, with or without computed tomography (CT)-based navigation. Our primary outcome measures were efficiency and accuracy of PSI. We analyzed the data with bivariate analyses using the Chi-square test for categorical variables and the Student t test or ANalysis Of VAriance with Bonferroni post-hoc tests for continuous variables. Results: The drilling techniques (free hand and navigated) were more efficient as compared with the pedicle probe techniques (P < 0.01). The navigated techniques resulted in better accuracy as compared with the free hand techniques (P = 0.036). Most pedicle breaches were medial (n = 32/52). The concave apical pedicle (T4 right side) had the highest incidence of breaches. There was no significant difference in efficiency comparing the free hand and the navigated pedicle probe techniques (P = 0.261) or comparing the free hand drilling and the navigated drilling techniques (P = 1.00). Conclusion: On site surgical simulation is a promising concept for teaching advanced procedural skills. Our findings suggest that navigation improves the accuracy of PSI while sequential drilling safely improves efficiency. Combining navigation with sequential drilling can significantly improve the accuracy and the efficiency of PSI in scoliosis surgery, as previously suggested with our published clinical data.

AB19

Comparison of non-operative versus operative management of resectable colorectal cancer in elderly patients: a systematic review

Background: In 2010, 1.3 million Canadians were aged 80 and older. This number is expected to more than double to 3.3 million by 2036. Colorectal cancer (CRC) is the third most common cancer in both men and women, with its highest incidence rate in septu- and octogenarians. As clinicians encounter a growing number of very elderly patients (80 years and older) with resectable colorectal cancer, justifying major surgery in a comorbid population with limited life expectancy is difficult. Therefore, this study aims to systemically review the available literature to compare non-operative management to surgical resection with respect to overall survival and quality of life. Methods: A systematic review was conducted, in accordance with the PRISMA guideline. MEDLINE, EMBASE and the Cochrane Database of Controlled Trials were searched from 2000 to 2020 with the assistance of a health information specialist and clinical expert in the field of colorectal surgery. Results: A total of 2441 abstracts were screened, 429 were selected for full texts review. 412 of these papers (96%) focused on surgical outcomes, such as long/short-term treatment outcomes (144/429), elderly vs non-elderly surgical outcomes (107/429) and laparoscopic vs open operative outcomes (55/429). 17 remaining studies commented on non-operative management for resectable cancer. Due to the high degree of heterogeneity, a descriptive analysis was performed. Overall survival was consistently found to be higher across all studies in the operative group [30 months – 68 months] compared to those treated conservatively [8 months – 48 months]. Conclusion: An overwhelming majority of CRC studies in the elderly focus on operative management. While survival outcomes are consistently poorer in the non-operative group with resectable CRC, little is still known about the natural history and quality of life of those who choose not to have surgery. Through this review, we have identified a gap in the literature in the very elderly diagnosed with resectable CRC where further research is needed.

AB20

Competency-Based Resident Evaluations: Neurosurgical Faculty Perspectives On Feasibility

Introduction: Competency-based medical education (CBME), an outcomes-based approach to medical education, has been implemented across many postgraduate medical education programs worldwide. The success of this educational paradigm shift requires frequent Faculty observation and evaluation of residents performing defined tasks of the specialty; i.e. entrustable professional activities (EPAs). A main challenge involves providing residents with frequent performance evaluations and feedback that are feasible for Faculty to complete. This study aims to define what is currently happening and what changes are needed to make CBME successful for the certification of neurosurgeons’ competence. Methods: A 55-item online questionnaire was sent via SurveyMonkey to neurosurgical Faculty across Canada. Results: 52 complete responses were received and achieved a distribution highly correlated to the number of Faculty neurosurgeons practicing in each Canadian province (Pearson’s r =0.94). Faculty reported currently taking a median of 10 minutes to complete a resident’s evaluation form and 67% (35/52) complete them at the end of a resident’s rotation block. Regardless of Faculty’s province of practice (p = 0.50) or years of experience (p = 0.06), Faculty reported 3 minutes (minimum: 1 min, maximum: 10 min, IQR: 3 min) as a feasible amount of time to spend completing an evaluation form following an observation of a resident’s performance of an EPA. If evaluation forms took 3 minutes to complete, 85% (44/52) of respondents would complete EPA evaluations on a weekly or daily basis. Faculty recommended 5 minutes as a feasible amount of time to provide oral feedback (IQR: 3.25 min) which was significantly higher (p= 0.00099) than their recommended amount of time for completing evaluation forms. The majority of Faculty (71%) stated they would prefer to access resident evaluation forms through a mobile application compared to other methods (p = 0.0032). Conclusions: To facilitate the successful implementation of CBME into neurosurgical training curriculum, resident EPA assessment forms should take three minutes or less to complete and be accessible through a mobile application.

AB23

Evolution of outcome and process-of-care measures during Enhanced Recovery After Thoracic Surgery

BACKGROUND: Effective adoption of Enhanced Recovery After Thoracic Surgery (ERATS) requires understanding how specific processes contribute to protocol success. A time course analysis was undertaken to evaluate how perioperative process and outcome measures evolve over time with ERATS at a high-volume thoracic surgical centre in Ontario. METHODS: Patients undergoing major elective thoracic surgery during a 9-month pre-ERATS implementation period (control) were compared to three trimonthly patient cohorts (1-3, 4-6, and 7-9 month post-ERATS implementation). Outcome measures including length of stay (LOS), 30-day readmission rates and emergency room (ER) visits, and adverse events (AEs) were compared. Process measures included time to out-of-bed, first activity, ambulation, first diet, first fluids, removal of first and last chest tube, epidural removal, patient-controlled analgesia removal, and discontinuation of foley catheter, IV and IV saline lock. Kruskal-Wallis test with Dunn’s post-hoc test was used to compare continuous variables. Pearson’s chi-squared test was used for categorical data. RESULTS: A total of 352 (mean age 65.5y, 167F, 185M) and 352 (mean age 64.5y, 162F, 190M) patients were included in the pre- and post-ERATS groups, respectively. Readmission rates, ER visits, and LOS steadily decreased throughout the three post-ERATS periods compared to control but did not demonstrate significance. Minor and any AEs increased immediately in the first 3 months after ERATS implementation before significantly improving in the 7-9 month post-ERATS group along with major AEs. Process measures for mobilization (time to first activity, ambulation, out-of-bed) improved immediately while time to discontinuation of foley improved in 4-6 month post-ERATS. Other process measures did not significantly differ compared to pre-ERATS. CONCLUSION: Process measures improved at different time frames with overall significance being demonstrated earlier than changes in outcome measures. These findings suggest that effective ERATS adoption is an accumulation of behaviour changes toward improving multiple processes which collectively achieves optimization of clinical outcomes.

AB25

Is intraoperative frozen section analysis of margins and re-resection of positive margins beneficial in patients undergoing resection of hilar cholangiocarcinoma? A systematic review and meta-analysis

INTRODUCTION: Perihilar cholangiocarcinoma (PHC) is a rare malignancy that arises anywhere from the common hepatic duct to the extrahepatic right or left hepatic ducts. Given the lack of effective systemic therapy, margin negative (R0) resection remains essential for long term survival. The objective of this review is to combine the data from studies addressing the issue of re-resecting a positive proximal and/or distal intraoperative frozen bile duct margin in PHC to determine the impact of re-resection on clinical outcomes. METHODS: MEDLINE, EMBASE, and Cochrane databases were searched from inception to October 5th, 2020 to identify studies comparing patients undergoing surgical resection of PHC with intraoperative frozen section of the proximal and/or distal bile ducts who were initially margin-negative (R0), initially margin-positive but who underwent successful re-resection (R1R0), or had a persistently positive margin with or without additional resection (R1). The primary outcome of interest was overall survival (OS). Secondary outcomes included rate of postoperative complications such as biliary fistula. RESULTS: 409 studies were screened. Ten retrospective observational studies reporting on 1955 patients were included. Patients undergoing successful re-resection of a positive proximal and/or distal intraoperative frozen bile duct margin (R1R0) had similar OS to those with a primary margin-negative resection (R0) (HR 0.93, 95% CI 0.72-1.19, p=0.56, I2 = 84%) and significantly better OS than patients with a persistently positive bile duct margin (R1) (HR 0.52, 95% CI 0.34-0.79, p=0.002, I2 = 0%). There was no increase in the rate of postoperative complications associated with additional resection, although postoperative morbidity was poorly reported across included studies. CONCLUSIONS: The current review supports frozen section evaluation of margins during resection of PHC, and re-resection if technically feasible, given the significant survival advantage of a negative margin without additive perioperative morbidity.

AB26

Measuring Cost of Adverse Events Following Thoracic Surgery: A Systematic Review

INTRODUCTION: Costs of adverse events (AE) following thoracic surgery places a substantial burden on an already prohibitively expensive health care system. Any adverse event, no matter how minor, can impact patient experience, length of stay and cost. An economic evaluation identifying the most common and costly AE associated with thoracic surgical procedures will guide healthcare delivery and cost-saving efforts. The objective of this study is to determine the costs associated with AE following thoracic surgery. METHODS: We performed a systematic search of studies estimating the cost of AE from thoracic surgery within the following databases: MEDLINE, Embase, The Cochrane Library. Study inclusion criteria entailed: patients who had undergone thoracic surgery procedure; and an estimated cost of a post-operative AE associated with a thoracic surgery procedure. There were no language restrictions. Studies published after 2000 were included to capture relevant costs. All costs were adjusted to 2020 US dollars to facilitate comparison. RESULTS: A total of 1,024 abstracts were identified, of which 20 studies met inclusion criteria. Majority of studies were conducted in the USA (17/20). The ten (10) most common AE included: Air leak, atrial fibrillation, bleeding, bronchospasm, pneumothorax, pneumonia, respiratory failure, emphysema with fistula, hemoptysis and acute kidney injury. Estimated mean costs of AE ranged from $23,355 (emphysema with fistula) to $8,085 (bronchospasm), with other costs falling in between this range. CONCLUSION: Costs associated with AE in thoracic surgery are substantial. Insight into the type of AE will identify potential cost-saving and quality improvement interventions. Further analysis and generation of models capable of identifying patients at risk for AE will augment clinical experience while promoting a reduction in health-care costs.

AB27

Division wide implementation of an Enhanced Recovery After Thoracic Surgery (ERATS) program – longitudinal impact on postoperative outcomes, processes of care, patient satisfaction and quality of life

INTRODUCTION: Enhanced recovery after surgery has demonstrated impact in multiple surgical domains; however, data on thoracic surgery is sparse and inconsistent. This study aims at evaluating the effects of implementing an Enhanced Recovery After Thoracic Surgery (ERATS) program on postoperative outcomes, processes of care outcomes, anesthesia management, patient satisfaction, and quality of life (QOL). METHODS: We conducted a prospective, longitudinal study evaluating 9 months before and 9 months after a 3-month implementation of an ERATS program. All consecutive patients undergoing major thoracic surgery were included. The primary outcomes were length of stay (LOS), adverse events (AE), 30-day re-admissions, 30-day ER visits, and postoperative 6-minute walk test. In terms of process of care outcomes, the following variables were collected: time to ‘out-of-bed’, independent ambulation, successful fluid intake, last chest tube removal, and urinary catheter removal. We also obtained information related to anesthesia care, patient satisfaction, and QOL scores at 4 weeks and at 6 months. RESULTS: The pre-ERATS (n=352) and post-ERATS (n=352) groups demonstrated no difference in baseline characteristics and surgical procedures, except for gastrectomy and lobectomy. Post-ERATS patients had a significantly shorter LOS (4.7 vs. 6.2 days, p<0.02), with no difference in major or minor AE. Although there was no statistically significant difference in 30-day readmission rate, there were less 30-day ER visits in the post-ERATS group (13.7 vs. 21.6%, p=0.03). In addition, this group had higher 6-minute walk test scores (402+85 vs. 371+107 meters, p=0.0005). With respect to process of care outcomes, post-ERATS patients experienced shorter mean time to ‘out-of-bed’, independent ambulation, successful fluid intake, and urinary catheterization. There were no significant differences in anesthesia care, patient satisfaction, and QOL scores at 4 weeks and at 6 months. CONCLUSION: Implementation of a comprehensive ERATS program is effective and safe in reducing LOS without affecting patient satisfaction or QOL. Ongoing research will help further refine best ERATS practices.

AB28

Outcomes of abiraterone plus prednisone versus docetaxel in metastatic hormone-sensitive prostate cancer in a real-world setting

INTRODUCTION AND OBJECTIVE: We compared outcomes of patients treated with Docetaxel (DOC) or Abiraterone + Prednisone (AA+P) plus androgen deprivation therapy (ADT) in patients with metastatic hormone-sensitive prostate cancer (MHSPC) in a real-world setting. METHODS: A retrospective chart review of patients treated with either DOC or AA+P at The Ottawa Hospital from January 1, 2014 to April 1, 2017 (DOC group), and from January 1, 2017 to March 14, 2019 (AA+P group). We included patients with hormone-sensitive disease who received ADT for the first time. The primary outcome was overall survival rate (OS). Secondary outcomes included radiological progression-free survival (rPFS) and PSA progression-free survival (pPFS). We also identified factors associated with survival. RESULTS: 102 eligible patients with MHSPC treated with DOC or AA+P were identified. Mean age was 66 years in DOC group, and 72 years in AA+P group (p<0.05). The median PSA at diagnosis in the DOC group was 175, and 151 in AA+P group (p= 0.3). Most patients in both groups had Gleason ≥8 (DOC 95%, AA+P 86%). The mean follow up in DOC group was 26 months, and AA+P was 15 mo (p<0.05). For the DOC group, nadir PSA levels 6 months post-initiation of ADT were < 0.2, 0.2-1, 1-4, and > 4 ng/mL in 18%, 35%, 15%, and 32%, respectively. For the AA+P group, nadir PSA levels 6 months post-initiation of ADT were < 0.2, 0.2-1, 1-4, and > 4 ng/mL in 38%, 19%, 15%, and 28%, respectively.Patients receiving Abiraterone had superior pPFS (p=0.0117). rPFS was not statistically different (p=0.3634). The only predictor of pPFS and rPFS was PSA 6 months post-initiation of ADT. Patients with PSA >4 vs <0.2, and PSA >1-4 vs <0.2 had increasingly greater results of failure. OS did not differ significantly between groups (p=0.16). The only predictor of OS was the PSA at 6 months >4 vs <0.2 HR 13.85 (95% CI 1.06 – 179.73). CONCLUSIONS: In our cohort study, DOC and AA+P groups had comparable survival endpoints. PSA nadir 6 months post-initiation of ADT appears to be an important predictor of OS, pPFS and rPFS. Patients who failed to reach PSA <1 had worse rPFS and pPFS. Patients who did not reach PSA <4 had a poor OS rate.

AB29

A chance for reform: the environmental impact of travel for general surgery residency interviews

INTRODUCTION: In light of the global climate emergency, it is worth reconsidering the current practice of medical students traveling to interview for residency positions. We sought to estimate carbon dioxide (CO2) emissions associated with travel for general surgery residency interviews in Canada, and the potential avoided emissions if interviews were restructured. METHODS: An 8-item survey was constructed to collect data on cities visited, travel modalities, and costs incurred. Applicants to the University of Ottawa General Surgery Program during the 2019/20 Canadian Resident Matching Service (CaRMS) cycle were invited to complete the survey. Potential reductions in CO2 emissions were modeled using a regionalized interview process with either 1 or 2 cities. RESULTS: Of a total of 56 applicants, 39 (70%) completed the survey. Applicants on average visited 10 cities with a mean total cost of $4,866 (95% CI=3,995-5,737) per applicant. Mean CO2 emissions were 1.82 (95% CI=1.50-2.14) tonnes per applicant, and the total CO2 emissions by applicants was estimated to be 101.9 (95% CI=84.0 – 119.8) tonnes. In models wherein interviews are regionalized to 1 or 2 cities, emissions would be 57.9 tonnes (43.2% reduction) and 84.2 tonnes (17.4% reduction) respectively. Overall, 74.4% of respondents were concerned about the environmental impact of travel, and 46% would prefer to interview by videoconference. CONCLUSION: Travel for general surgery residency interviews in Canada is associated with a considerable environmental impact. These findings are likely generalizable to other residency programs. Given the global climate crisis, the CaRMS application process must consider alternative structures.

AB30

Targeting CD155 Poliovirus Receptor: A Novel Strategy to Prevent Postoperative Immunosuppression in Cancer Patients

INTRODUCTION: Despite benefits of primary tumour resection, invasive surgery can lead to increased tumour seeding and metastases. Surgical stress releases some myeloid cells with suppressive properties, termed MDSCs, that directly inhibit NK cells. Poliovirus receptor CD155 is found at low levels in normal tissue but is highly expressed in various cancers. Furthermore, CD155 is highly expressed on myeloid cells isolated from the tumour microenvironment. Overexpression of tumour CD155 causes strong NK cell suppression, which makes it an appealing perioperative target for immunotherapy. METHODS: Murine: B16 melanoma and anti-CD155 antibody were injected into mice followed by laparotomy and nephrectomy. On POD1 or POD3, mice were sacrificed to process spleen for analysis. Human: Blood was collected on POD0 and POD1 from 20 cancer patients. Peripheral blood cells were isolated by Ficoll gradient and cells analyzed for CD155 expression. Human suppression assay: MDSCs and healthy donor NK cells were co-incubated with K562 leukemia target cells and analyzed for NK cytotoxicity. RESULTS: In our animal model, there is a significant increase of MDSC CD155 after surgery (n=36, p<0.0001), whereas granulocyte CD155 is minimal (n=36, p=0.44). In human patients, MDSC CD155 expression increases significantly on POD1 (n=20, p<0.0001). Subgroup analysis suggests that CD155 correlates with cancer type and stage. In vivo CD155 blockade in our animal model resulted in improved NK cell phenotype (n=8, p=0.02) and cytotoxicity after surgical stress. In ex vivo human suppression assays, anti-CD155 significantly decreased the suppressive effect of MDSCs on NK cells by nearly 50%. CONCLUSION: In summary, CD155 is significantly upregulated on MDSCs after surgery, whereas other cell types have minimal CD155 expression. CD155 blocking experiments led to improved NK cell phenotype and cytotoxicity. To our knowledge, this study is the first of its kind to determine a link between CD155 expression on MDSCs and postoperative suppression of NK cells. Future work targeting CD155 appears very promising to minimize postoperative immunosuppression and improve outcomes in cancer surgery patients.

AB33

Understanding breast cancer laterality to improve treatment and training in General Surgery

Background Interest in the laterality of breast cancer stems from the first half of the 20th century, following publications by von Fellenberg (1940) and Lane-Claypon (1926). Since then, it has been consistently documented that the left breast is 5-10% more likely to develop cancer than the right breast (Von Fellenberg, 1940; Lane-Claypon, 1926; Garfinkel, 1974; Senie, 1980; Ekbom, 1994; Tulinius, 1990). The higher prevalence of left-sided breast cancers is small, consensus seems to be that it does not impact overall survival, although a study by Fatima et al. (2013) found right-sided breast cancers had a more aggressive behaviour. Many studies agree against these co-morbidities being coincidental, however no explanation or mechanism has been proposed to explain the importance and key factors of the laterality of breast cancer. Objectives Based on observations of the laterality of breast cancer, do the observations on the prevalence and behaviour of left-sided vs. right-sided breast cancer hold true in the context of patients treated at the Montfort Hospital? If so, what are the factors that may contribute to such observations, and did the outcomes vary between different breast cancers? Methods We performed a retrospective sectional study of patients records with pathologically confirmed breast cancer or DCIS, ranging 2014 to 2019 (19-20-02-041). Results Our study population (N=145) is largely composed of women (99.3%) aged 50 to 89 years old (85.5%). Left, right, or both breasts were affected in 44.8%, 39.3% and 13.8% of cases respectively. When including the severity of each side (carcinoma, malignant neoplasm or overlapping neoplasm), we found that the side the most responsible for surgical intervention was the left, right and both sides in 46.2%, 40.0% and 11.0% of cases respectively. Conclusion Preliminary data shows that breast cancers have a very slight preference for targeting the left breast, albeit statistically non-significant. Further analyses, including surgical intervention type and outcome, are required to better explain the slight variation observed and to potentially reveal differences between either left-sided or right-sided breast cancers.

AB34

Assessing self-awareness in general surgery applicants: an insight into interview performance

Background: Selecting medical students for residency is a subjective and competitive process, with identifiable top and bottom applicants but a narrow range of scores separating the middle cohort. Literature demonstrates that personal characteristics may be more accurate at predicting performance during residency than objective measures. Self-awareness is a characteristic positively associated with performance and leadership skills, often measured using self-assessment of performance as a surrogate. Our objective was to investigate the relationship between self-awareness and interview performance as an adjunct to discriminate between applicants. Methods: At the University of Ottawa in 2020, 56 applicants completed an interview circuit that consisted of nine interview stations, each assessing a different characteristic or skill important for success in general surgery. Fifty-five applicants completed a self-assessment questionnaire after the interview, evaluating their perceived performance on each station. Pearson’s correlation was used to determine the relationship between self-assessment and interviewer scores. Results: Out of 30 points per station, there was a wide range of self-assessment (6-30) and interview scores (7-30). There was a significant negative correlation between self-assessment and interview scores for seven of nine interview stations (r = 0.60-0.73, p<0.05). High performers underestimated their interview performance, while low performers overestimated their performance. Two stations where self-assessment was not significantly correlated with interview performance involved clinical tasks. Conclusion: Self-assessment of performance during residency interviews negatively correlates with interview performance, with the possible exception of stations relating to clinical tasks. Self-assessments provide additional information that may be valuable in discriminating between applicants with similar interview scores.

AB35

Post-prostatectomy adjuvant androgen deprivation therapy— current opinions and practices of Canadian urologists

INTRODUCTION: Despite the proven benefit of adjuvant androgen deprivation therapy (ADT) for patients receiving primary radiation, there are few studies evaluating adjuvant ADT after prostatectomy. In the absence of evidence, opinions and practice patterns may vary. We surveyed Canadian prostate cancer surgeons about their use of adjuvant ADT and their opinions on an adjuvant ADT trial design. METHODS: An electronic survey was designed and distributed using a modified Dillman approach. The survey was sent to 38 urologists who perform radical prostatectomy and represent all 17 major academic institutions and all 10 Canadian provinces. Surgeons were queried about their current use of adjuvant ADT and their opinions regarding the need for a clinical trial. To inform trial design, we asked respondents their opinions about which patients should be eligible, what duration of ADT is most appropriate, and what outcomes are clinically meaningful. The survey was sent out in February 2020 and all responses were received by March 2020. RESULTS: All 38 (100%) invited urologists completed the survey. Only 3 (7%) respondents currently offer post-operative adjuvant ADT as an option for patients without metastases. Thirty-five (92%) urologists believed that a trial is needed before short-term adjuvant treatment should be offered to prevent recurrence. Seventeen (45%) urologists believed an adjuvant ADT trial was most appropriate for patients with an estimated PSA recurrence risk of >25% and 16 (42%) believed a recurrence risk of >50% was most appropriate. Twenty-five (66%) respondents believed 12 months of adjuvant ADT was the optimal duration for a randomized trial. 37 (97%) respondents felt that prolonging the time to PSA recurrence and/or pelvic radiation was a clinically important outcome. The majority (20; 53%) of respondents would recommend 12 months of adjuvant ADT if a randomized trial showed a 50% relative risk reduction in PSA recurrence. CONCLUSION: Canadian prostate cancer surgeons do not offer adjuvant ADT following prostatectomy. Based on the results from this survey, a randomized trial is needed, feasible, and would influence patient care.

AB36

Association between radical cystectomy prophylactic antibiotic regimen and post-operative infection

Introduction: Infection is common after radical cystectomy. Peri-operative antibiotic prophylaxis is recommended to reduce infection, however, there is a lack of cystectomy specific data on optimal regimen and duration. The primary objective of this study is to determine the association between antibiotic prophylactic regimen and infection after radical cystectomy. Methods: A retrospective review on all patients who underwent radical cystectomy at a tertiary Canadian centre between January 2016 and April 2020 was performed. All patients received antibiotic prophylaxis (cefazolin/metronidazole, ampicillin/ciprofloxacin/metronidazole, other). The incidence of 30-day infection (surgical site infection or urinary tract infection) was determined. A univariable and multivariable logistic regression model was created to determine association of prophylactic antibiotic regimen with post-operative infection. Bacterial resistance patterns were collected for all tested antibiotic sensitivities and overall resistance to each prophylactic regimen was calculated. Results: In total 165 patients were included. Mean age was 69.8 years, 121 (73.3%) were male, and 72 (43.6%) underwent orthotopic neobladder diversion. Ninety-six patients (58%) received cefazolin/metronidazole prophylaxis, 50 patients (30%) received ampicillin/ciprofloxacin/metronidazole, and 19 patients (11.5%) received an alternative regimen. Surgical site infection occurred in 35 patients (21.2%) and urinary tract infection occurred in 34 (21.0%). Fungal infection occurred in 10 patients (14.5%). Among patients with positive cultures, overall bacterial resistance was 42% for cefazolin/metronidazole and 18% for ampicillin/ciprofloxacin/metronidazole. There was no association between antibiotic regimen used and incidence of post-operative infection (surgical site infection or urinary tract infection, RR 0.99; 95% CI 0.50-1.99). Conclusions: Infection is common post-radical cystectomy. Despite differences in resistance patterns, there was no association with antibiotic regimen and incidence of infection. Further study is required to determine optimal prophylactic antibiotic regimen and duration.

AB37

A renal tumour prediction tool using the Canadian Kidney Cancer Information System

Introduction: With the increased use of cross-sectional images, incidental kidney tumours are frequently discovered. However, many surgically removed kidney tumours are found to be benign, and some cancerous tumours are indolent. We sought to determine the clinical and radiographic predictive factors of kidney tumour malignancy and develop a nomogram to distinguish between benign and malignant renal masses. Methods: Patients diagnosed with solitary renal masses were identified from the Canadian Kidney Cancer information system. Demographic, clinical, and imaging data were compared to the pathologic diagnosis from surgery or biopsy. Tumours were categorized into malignant or benign, and aggressive (high-grade malignant) or indolent (low-grade malignant and benign). Logistic regression models were constructed to identify predictors of each category. Nomograms were created using statistically significant risk factors and were internally validated using bootstrap methods. Results: Of 4,438 patients diagnosed with a solitary kidney tumour between January 2011 and March 2020, 92% patients had malignant tumours, and 43% had high grade tumours. Factors associated with cancer and high-grade cancer were male sex (Odds Ratio [OR] 1.64; 95% confidence interval [CI] 1.31-2.06; OR 1.66, 95%CI 1.43-1.92, respectively) and tumour size (OR 1.24, 95%CI 1.18-1.31; OR 1.29, 95%CI 1.25-1.32, respectively). Older age was also predictive of high-grade cancer (OR 1.06, 95%CI 1.03-1.09). The nomograms were able to discriminate between malignant/benign tumours (area under the curve [AUC]= 0.72, 95%CI 0.70-0.75), and aggressive/indolent tumours (AUC=0.77, 95%CI 0.75-0.78). Conclusions: Patient and tumour characteristics are independently associated with cancer risk and high grade-cancer risk. The CKCis nomograms presented have good discriminative accuracy and this prediction tool can be used by physicians and patients with kidney tumours to help determine an optimal management plan.

AB38

A retrospective cohort study of patients undergoing elective bowel resection before and after implementation of an anemia screening and treatment initiative.

INTRODUCTION: Numerous studies have demonstrated that between 40-47% of patients undergoing elective bowel resection have pre-operative anemia. The objective of this study was twofold: 1. To implement an anemia screening and treatment program in patients undergoing elective colon and rectal resections. 2. To compare the outcomes of patients undergoing elective bowel resection before and after implementation of our anemia identification and treatment initiative. METHODS: From March 2018 to April 2019 we implemented a quality improvement program designed to identify and treat patients with pre-operative anemia undergoing elective bowel resection. Using clinic collected and NSQIP procedure targeted data we then compared a cohort of patients undergoing elective bowel resection pre-implementation (Pre-I) (March 2017 to February 2018) to the cohort post-implementation (Post-I) (April 2018 to April 2019). The primary outcome was cost per admission. Secondary outcomes included anemia screening and treatment rates, rate of blood transfusion, complications, mortality. RESULTS: Of the 84 patients in the Pre-I cohort 44 (55.9%) were anemic, and 47 (54.7%) were anemic in the Post-I cohort. Of the 88 patients in the Post-I cohort, 74 (84.1%) were screened in clinic for anemia and 30 (34.1%) underwent treatment. Total cost per admission was significantly decreased in the Post-I cohort compared to the Pre-I cohort (mean cost $16,248 vs. $25,796, p = 0.004). There was no significant difference in rates of blood transfusion (15.5% Pre-I vs. 6.8% Post-I), complications (14.3% Pre-I and 12.5% Post-I) or mortality (0% Pre-I vs. 2.3% Post-I) between the groups. Using regression analysis there was a 24% reduction in encounter cost in the Post-I cohort compared to the Pre-I group (ratio of means 0.76, 95% CI: -33%, -12%). CONCLUSIONS: We demonstrate the successful implementation of an anemia screening and treatment program in a colorectal surgery clinic. This program was able to significantly reduce cost per admission by 24%.

AB40

A systematic review and meta-analysis of randomized controlled trials comparing intraoperative red blood cell transfusion strategies

INTRODUCTION: Red blood cell (RBC) transfusions are common in surgery and associated with widespread variability despite adjustment for casemix. Recommendations guiding RBC transfusion in the operative setting are limited. The objective is to carry out a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing intraoperative RBC transfusion strategies (e.g. transfusion algorithms, hemoglobin triggers) in surgical patients to determine their impact on postoperative morbidity and mortality, as well as blood product use. METHODS: The search strategy was adopted from a previous Cochrane Review. EMBASE, MEDLINE, and The Cochrane Central Register of Controlled Trials were searched from January 2016 to July 2019. Included studies from the previous Cochrane Review were reviewed to identify eligible studies from prior to 2016. RCTs comparing a minimum of two intraoperative transfusion strategies were considered for eligibility. Primary outcomes were 30-day mortality and morbidity. Secondary outcomes were the rate of intraoperative and overall RBC transfusion. RESULTS: 11 studies (7668 patients) were included. There was no significant difference in 30-day mortality between restrictive and liberal transfusion groups (RR 0.92, 95% CI 0.72-1.18). There was no significant difference in pooled postoperative morbidity among the studied outcomes. Two trials reported worse composite outcomes with restrictive triggers. It was not possible to pool overall 30-day morbidity given the heterogeneity of reported outcomes. Incidence of both intraoperative (RR 0.57, 95% CI 0.44-0.75) and perioperative (RR 0.76, 95% CI 0.68-0.86) blood transfusion were lower in the restrictive group compared to the liberal group. CONCLUSION: Intraoperative restrictive transfusion strategies decreased perioperative RBC transfusion without increased morbidity and mortality in all but two trials. Given trial design and generalizability limitations, uncertainty remains regarding the safety of broadly applying restrictive transfusion triggers in the operating room. Trials specifically designed to address intraoperative transfusions are urgently needed.

AB41

The gap in urology resident understanding of a robotic prostatectomy and what residents do not perceive when assisting

INTRODUCTION: Robotic surgery, and the robotic prostatectomy, have been adopted into urology training programs internationally. With the need for dedicated robotic training programs, we sought to explore the knowledge gap and needs assessment to add to these programs. This study aimed to determine what is the difference in understanding of a robotic prostatectomy for residents compared to urologists. METHODS: A 16-question survey, composed of both quantitative and qualitative questions, was developed to document the difference in understanding between residents and urologists. The survey contained items pertaining to patient anatomy, procedural steps and surgical decision-making. Urology residents performing as bedside assistants were surveyed directly after the robotic prostatectomy. Urologists performing the same procedure were also surveyed directly after the operation. Statistical analysis of the quantitative questions was performed using percent agreement and kappa scores and coding and thematic analysis was performed to analyse the qualitative responses. RESULTS: The survey was administered to urology residents and urologists at The Ottawa Hospital. 42 surveys were completed over 10 weeks. There was disagreement between urology resident and urologist responses. The most disagreement was noted with the comparison of the following procedural steps: vesicourethral anastomosis (kappa 0.138), apical dissection (kappa 0.149), and seminal vesicle dissection (kappa 0.342). The qualitative responses found discrepancies between resident and urologist understanding as well. When asked to describe challenges during the procedure, urologists tended to describe causal factors leading to challenges and how to manage these issues intraoperatively. The residents’ responses tended to focus more on readily visible aspects of the procedure, like bleeding or difficulty with exposure, without describing the cause of these challenges. CONCLUSION: There is a gap in urology resident knowledge and understanding of a robotic prostatectomy. This information is key to expand the understanding of robotic prostatectomy surgical decision-making and its training.

AB43

The Effect of Immediate Breast Reconstruction on Adjuvant Therapy Delay, Locoregional Recurrence and Disease-Free Survival

INTRODUCTION: An important risk inherent to both alloplastic and autologous Immediate Breast Reconstruction (IBR) is the higher incidence of postoperative complications and delays to adjuvant therapy; There is a paucity of literature investigating the impact of IBR on locoregional recurrence risk (or breast cancer-free survival). This study investigated whether postoperative complications and delays to adjuvant therapy had an impact on long-term therapeutic outcomes. METHODS: A 6-year retrospective study of breast cancer patients treated with mastectomy only (MO) or mastectomy with IBR (MIBR) was conducted from Jan/2013 to May/2019. The main outcomes of interest were time to adjuvant therapy (and delays), postoperative complications, and locoregional recurrence. Cox regression was used to estimate the risk for locoregional recurrence and increased time to adjuvant therapy according to variables of interest. RESULTS: Of 1832 patients reviewed, 726(40%) were included. 449(62%) MO and 277(38%) MIBR [140(51%) 1-stage direct to implant (MIBRi1), 96(35%) 2-stage tissue-expander to implant (MIBRi2), 41(15%) autologous flap (MIBRf)]. 358(80%) MO and 213(78%) MIBR received adjuvant chemoradiotherapy. MIBR had significantly more delays to adjuvant radiotherapy vs. MO [113(70%) vs. 72(80%) months, p = 0.022]. MIBR experienced significantly more major complications vs. MO [MO: 41(9.13%); MIBR: 82(34.0%), p = 0.018]. MIBRi2 demonstrated a 3.91-times higher risk for locoregional recurrence vs. MO [HR: 3.91; 95% CI: 3.37, 4.46]; There were no significant confounders. MIBR had significantly increased time to radiotherapy vs. MO [HR: 0.750, 95% CI: 0.576, 0.974]; This effect for MIBR was not significant after adjusting for age [aHR: 0.968, 95% CI: 0.707, 1.32]. CONCLUSIONS: There was a greater proportion of major complications and delays to adjuvant radiotherapy in the MIBR group (vs. MO); However, major complications and delays to adjuvant radiotherapy did not significantly increase the risk for locoregional recurrence. There is a need for further research to explore the underlying mechanism(s) for the increased risk of locoregional recurrence in MIBRi2 (vs. MO).

AB44

Measuring surgeon empathy: implementation, results and validity of the CARE measure survey from a trans-departmental initiative

Objective: This study assesses empathy and communication skills among a group of surgeons within a single academic institution. Background: The Consultation and Relational Empathy (CARE) measure is a validated questionnaire designed to assess patients’ perceptions of their physician’s communication skills and empathy. It has previously been used to assess empathy in medical specialties but has seldom been applied to surgery. Methods: All surgeons within the Department were invited to participate. Patients seen in clinics of participating surgeons were recruited prospectively. At the end of each clinical encounter they were asked to complete a CARE survey. Data were collected over a six-month period and surveys were analyzed according to previously validated inclusion and exclusion criteria. Mean scores for each surgeon and surgical division were calculated. All surgeons were then provided with their individual score and de-identified Division scores. They were then asked to complete a survey assessing their attitudes towards the survey. Results: 44 surgeons and 1801 surveys were included in the final analysis. The average CARE score across the Department was 46.9 (95% CI 46.6-47.1). Female surgeons received significantly higher scores than males (mean 47.6, 95% CI 47.1-48.0 vs mean 46.7, 95% CI 46.4-48.0, p=0.001). Of 35 surgeons surveyed after study completion, 31 (89%) felt that the questions included in the CARE measure applied to their practice. Conclusions: Our results demonstrate high communication and empathy scores among surgeons in the outpatient setting, with enough variability to encourage continued improvement. This appears to be a valid measure in surgeons and the vast majority find it relevant to their practice.