ILD: Indications for Surgical Lung Biopsy and Risk Stratification

• Authors: Laura Donahoe & Sean McFadden
• Reviewer: Anne-Sophie Laliberte & Andrew Seely

Background

Interstitial Lung Diseases (ILDs) are a group of heterogeneous diseases of the lung, with variable clinical features, treatment and prognosis. The diagnosis of ILD is based on clinical features, temporal behaviour of symptoms and findings on high-resolution computed tomography (HRCT).  In patients with clinical features of idiopathic pulmonary fibrosis (IPF) and findings of usual interstitial pneumonia (UIP) on HRCT, a diagnosis of IPF can be made without histologic confirmation as long as alternative causes of ILD have been ruled out.   These two factors are sometimes not sufficient to make a diagnosis, though, such as in cases with atypical findings on HRCT [1].  Although the list of ILDs is extensive and many specific diagnoses are treated quite similarly, for some ILDs it is very important to establish a diagnosis prior to initiating treatment.  For patients with IPF, the PANTHER trial from 2011 showed increased mortality with prednisone, azathioprine and N-acetylcysteine NAC  [2].  Also, with the introduction of the anti-fibrotic pirfenidone in 2012 came the requirement from Health Canada to show histologic proof of IPF [3].

Technically, a surgical lung biopsy (SLB) is a very straightforward procedure.  The HRCT is reviewed to ensure that biopsies are not taken from the most severely affected areas of the lung, especially areas of honeycombing, as the histology from these areas usually shows end-stage fibrosis and is non-diagnostic.  Two or more biopsies are taken from different lobes of the lung as there can be discordant findings throughout the same lung [1].  The surgery can be performed by VATS or open approach, with VATS preferred when possible.

Although not a particularly technically challenging procedure, the concern about performing SLB comes from the relatively high mortality rates associated with the surgery.  There are varying reports of mortality rates post SLB, with rates as high as 70% in historical reports [1].  A number of recent studies have re-examined mortality rates, and have found large differences based on whether the procedure is elective (1.7%) or emergent (16%)(see Figure 1)[4].  Fisher et al found that hospitals with higher SLB volume had lower mortality rates, but in examining the data they found that the difference was more related to patient factors and not technical factors [3].  Older age, male sex, non-elective procedure, home oxygen use, higher Charlson Comorbidity Index, and open rather than VATS approach have been shown to be associated with higher mortality in a number of studies [3,4].In a review of all SLB performed in the United States over an 11 year period, a complication rate of 30% was found for elective procedures.  Thus, patient selection is key in performing SLB.

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