Predictive factors for the long-term use of pirfenidone in patients with fibrosing interstitial lung disease.

Abstract

Pirfenidone is an anti-fibrotic agent approved for idiopathic pulmonary fibrosis (IPF), and long-term treatment data and the effect of continuation after disease progression have been reported. The efficacy and safety of pirfenidone in fibrosing interstitial lung disease (ILD) patients without IPF have been recently reported in clinical trials; therefore, the benefits of long-term treatment are also expected. This study aims to analyze the long-term treatment data of pirfenidone and clarify the predictive factors for long-term use of pirfenidone in non-IPF patients. We retrospectively reviewed the records of consecutive fibrosing ILD patients who started using pirfenidone between 2008 and 2014. Of the 266 fibrosing ILD patients, 167 patients had IPF, and 99 had non-IPF. Despite the non-significant differences in body size and pulmonary function between IPF and non-IPF patients, the non-IPF patients had better overall survival than the IPF patients (median 4.06 years vs. 2.09 years, p<0.0001). In addition, the non-IPF patients had a significantly longer time to treatment discontinuation than the IPF patients (median 2.20 years vs. 1.20 years, p=0.002). Multivariate logistic regression analysis for ≥2 years of use of pirfenidone showed that the percent predicted forced vital capacity (%FVC) and age were predictive factors common to both IPF and non-IPF patients. Our results indicate that non-IPF patients can continue using pirfenidone for longer durations than IPF patients. Initiation of pirfenidone for fibrosing ILD patients with higher %FVC and younger age would lead to long-term use of pirfenidone.