Contributing factor for the pirfenidone dose reduction in patients with idiopathic interstitial pneumonia in real-world settings—A dose-specific analysis

Abstract

Abstract Background Pirfenidone slows the progression of interstitial lung disease; however, in real-world settings, many patients discontinue or reduce its dosage owing to its adverse events. The contributing factors of low maintenance doses of pirfenidone have not been fully analyzed in a dose-specific manner. The aim of the current study is to identify the contributing factor of low-dose pirfenidone at < 1,200 or ≤ 1,200 mg/day in a dose-specific manner in real-world settings and to investigate the survival of patients stratified by the dose of pirfenidone as an exploratory analysis. Methods We retrospectively reviewed the clinical information and data from medical records of 85 patients with idiopathic interstitial pneumonia treated with different doses of pirfenidone at the University Hospital from April 2009 to August 2019. The contributing factors of the treatment dose were analyzed by performing a multivariate logistic regression analysis. Results The mean administered dose of pirfenidone was 1,242 mg/day, and the doses were 1,800, 1,200, and < 1,200 mg/day in 25.9%, 54.1%, and 20% of patients, respectively. The treatment doses in the ≤ 1,200 and < 1,200 mg/day groups were 1047.6 ± 255.8 and 635.3 ± 78.6 mg/day, respectively. Patients’ age was significantly related to the treatment dose of ≤ 1,200 mg/day, with most patients receiving 1,200 mg/day. Contrarily, pulmonary dysfunction and hypoalbuminemia were related to a dose of < 1,200 mg/day. Survival was significantly shorter in the < 1,200 mg/day group than in the 1,800 mg/day group. The pirfenidone dosage of < 1,200 mg/day and low forced vital capacity were independently associated with a poor prognosis. Conclusions Pulmonary dysfunction and hypoalbuminemia were identified as contributing factors of the maintenance of low-dose pirfenidone at < 1,200 mg/day. Early intervention is important before the progression to severe disease accompanied by decreased pulmonary function or malnutrition.