Pirfenidone in Progressive Pulmonary Fibrosis A Systematic Review and Meta-Analysis

Background: The American Thoracic Society, European Respiratory Society, Japanese Respiratory Society, and Asociacion Latinoamericana del Torax convened to update clinical practice guidelines for interstitial lung disease (ILD). Objective: To conduct a systematic review to evaluate existing ILD literature to determine whether patients with progressive pulmonary fibrosis (PPF) should be treated with the antifibrotic pirfenidone. Data Sources: A literature search was conducted across MEDLINE, EMBASE, and Cochrane databases through December 2020 for studies using pirfenidone to treat patients with PPF. Data Extraction: Mortality, disease progression, lung function, and adverse event data were extracted. Meta-analyses were performed when possible. The Grading of Recommendations, Assessment, Development and Evaluation Working Group approach was used to assess the quality of evidence. Synthesis: Two studies met inclusion criteria. Meta-analyses revealed that changes in forced vital capacity (FVC) percent predicted (mean difference [MD], 2.3%; 95% confidence interval [CI], 0.5-4.1%), the FVC in milliliters (MD, 100.0 ml; 95% CI, 98.1-101.9 ml), and the 6-minute-walk distance in meters (MD, 25.2 m; 95% CI, 8.3-42.1 m) all favored pirfenidone over placebo. The changes in the diffusing capacity of the lung for carbon monoxide (DLCO) in millimoles per kilopascal per minute (MD, 0.40 mmol/kPa/min; 95%, CI 0.10-0.70 mmol/kPa/min) and risk of DLCO declining more than 15% (relative risk [RR], 0.27; 95% CI, 0.08-0.95) also favored pirfenidone. The risks of gastrointestinal discomfort (RR, 1.83; 95% CI, 1.29-2.60) and photosensitivity (RR, 4.88; 95% CI, 1.09-21.83) were higher with pirfenidone. The quality of the evidence was low or very low according to the Grading of Recommendations, Assessment, Development and Evaluation criteria, depending on the outcome. Conclusions: Pirfenidone use in patients with PPF is associated with a statistically significant decrease in disease progression and with protection of lung function. However, there is very low certainty in the estimated effects because of limitations in the available evidence.