Objective Long-term effects of pirfenidone have been poorly understood to date. This study investigated the clinical efficacy and safety of long-term pirfenidone use for idiopathic pulmonary fibrosis (IPF) in clinical practice.
Methods This survey study was a retrospective observational study. A survey was used to collect clinical information on IPF cases that were treated with pirfenidone. This survey sheet came from physicians belonging to the Diffuse Lung Diseases Research Group.
Results 502 patients at 22 institutes received pirfeidone treatment. Of the 502 cases, pirfenidone treatment was terminated in under one year in 186 cases (37.1%); adverse effect was the most frequent reason for termination. The pirfenidone treatment lasted for two years or longer in 111 cases (22.1%). The mean change in the forced vital capacity (FVC) was -30±224 (SD) mL in the first year of treatment, -158±258 mL in the second year, and -201±367 mL in the third year. FVC improved by 10% or more in the first year in 10 (14.7%) of 68 cases, and showed a change of ±10% in 47 (69.1%) cases. It showed a change of ±10% in the second and third years in 61.7% and 62.5% of the patients, respectively.
Conclusion The FVC improved in only a small percentage of patients who received pirfenidone treatment for a long period of time. However, a decrease in the FVC was prevented for three years in over half of the cases.