Pretreatment rate of decay in forced vital capacity predicts long-term response to pirfenidone in patients with idiopathic pulmonary fibrosis.

Pirfenidone reduces functional decline and disease progression in patients with Idiopathic Pulmonary Fibrosis (IPF). However, response to treatment is highly heterogeneous. In this study, we evaluated whether response to pirfenidone is influenced by the pre-treatment rate of forced vital capacity (FVC) decline. Fifty-seven IPF patients were categorized as rapid (RP) or slow progressors (SP) based on whether their FVC decline in the year preceding pirfenidone treatment was > or <10% predicted. Patients were followed-up every 6 months and up to 24 months following institution of pirfenidone treatment. In the entire population, pirfenidone reduced significantly the rate of FVC decline from 222 ml/yr to 68 ml/yr at 12 month (p<0.01) and 86 ml/yr at 24 month (p=0.04) follow-up. In RP, the reduction of FVC decline was evident at 6 months (706 ml/yr pre-treatment vs 35 ml/yr; p<0.01) and maintained, though to a lesser degree, at 12 (105 ml/yr; p< 0.01) and 24 months (125 ml/yr; p<0.02). Conversely, among SP the reduction in FVC decline was not significant at any of the time points analyzed. Pirfenidone reduces significantly the rate of FVC decline in patients with IPF. However, the beneficial effect is more pronounced and long-lasting in patients with rapidly progressive disease.