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

Pirfenidone reduces functional decline in patients with Idiopathic Pulmonary Fibrosis (IPF). However, response to treatment is highly heterogeneous. We sought to evaluate whether response to pirfenidone is influenced by the pretreatment rate of forced vital capacity (FVC) decline. Fifty-six 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. Following pirfenidone treatment patients were followed-up every 6 months and up to 24 months. In the entire population, pirfenidone reduced significantly FVC decline from 231 to 49 ml/year at 6 months (T6) (p = 0.003) and this effect was maintained at the 12-, 18- and 24-month time points (p value for trend n.s.). In RP, the reduction of FVC decline was evident at 6 months (36 vs 706 ml/year pretreatment; p = 0.002) and maintained, though to a lesser degree, at 12 (106 ml/year), 18 (176 ml/year) and 24 months (162 ml/year; p value for trend n.s). Among SP, the reduction in FVC decline was not significant at any of the time points analyzed. In conclusion, pirfenidone reduces FVC decline in IPF patients. However, its beneficial effect is more pronounced in patients with rapidly progressive disease.