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

Background: The American Thoracic Society, European Respiratory Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax 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. Primary Source of Funding: Funded by the American Thoracic Society, European Respiratory Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax.