Effect of antifibrotic agents on survival in idiopathic pulmonary fibrosis patients according to forced vital capacity: a real-world retrospective cohort study in Japan

Abstract Background Antifibrotic agents suppress the decline in forced vital capacity (FVC) and disease progression in idiopathic pulmonary fibrosis (IPF) patients. However, their effect on survival prognosis and differences in this effect according to baseline lung function have been unexplored. Therefore, this study aimed to examine the effect of antifibrotics on survival prognosis and whether this effect differed according to baseline FVC. Methods Consecutive IPF patients from January 2008 to May 2019 were examined retrospectively. FVC and effect of pirfenidone or nintedanib therapy were assessed. FVC at registration was used to categorize the patients into mild: FVC % predicted ≥ 80%, moderate: FVC % predicted 50–80%, and severe: FVC % predicted < 50% IPF groups. Results In total, 172 IPF patients were included. The mean FVC % predicted was 77.4 ± 22.2%. The median survival periods of patients in the mild, moderate, and severe IPF groups were 1,452, 1,305, and 481 days, respectively. Significant differences were observed in survival between the mild and severe groups and the moderate and severe groups (p < 0.0001), but not between the mild and moderate groups (p = 0.20). The survival was longer in patients on antifibrotic therapy in the mild (p = 0.18) and moderate groups (p = 0.04), but not in the severe group (p = 0.93). Conclusions Antifibrotics extended the survival of IPF patients. The effect was obvious in patients with FVC % predicted of 50–80%, a tendency was observed in patients with FVC % predicted ≥ 80%, while no effect was observed in patients with FVC % predicted < 50%.