Assessing the Therapeutic Response to Pirfenidone in Idiopathic Pulmonary Fibrosis: Can We Do Better than with Forced Vital Capacity Alone?

Abstract

New anti-fibrotic agents for idiopathic pulmonary fibrosis (IPF) were approved based on the results of forced vital capacity (FVC) trends, although concerns were raised about the reliability of FVC as the only endpoint parameter. We hypothesized that IPF-specific multi-dimensional scores (Composite Physiologic Index-CPI; gender-age-physiology-GAP; risk stratification score-RISE) would better capture response to therapy. In this pilot study, treated and untreated cohorts of IPF patients, matched for demographic and functional characteristics were prospectively followed for 1year, at 4-month intervals. Progression-free survival was significantly improved in treated patients (p=0.0093). While no difference in FVC longitudinal trends was observed, MRC dyspnea score (p=0.0347), diffusing lung capacity (p=0.0015), 6-min walk distance (p=0.0007), CPI (p=0.0457) and RISE (p=0.0005) were significantly stabilized in treated patients, compared to steady worsening in untreated subjects. Multi-dimensional scores provide broader spectrum of prognostic information and may facilitate the assessment of efficacy of new drugs for IPF.