The Role of Pirfenidone in the Treatment of Interstitial Pneumonia With Autoimmune Features

Abstract Rationale: No approved pharmacotherapies are available for patients with interstitial pneumonia with autoimmune features (IPAF). Objective: In the present work, we aimed to evaluate the efficacy and safety of pirfenidone for the treatment of IPAF.Methods: A retrospective cohort study consisting of patients who met diagnostic criteria for IPAF was performed after a multidisciplinary review, and the patients receiving pirfenidone were compared with those in the non-pirfenidone group. The baseline data and diagnostic characteristics of patients were assessed. Pulmonary function and prednisone dose were analyzed by a mix-effects model.Results: A total of 184 patients, who met the diagnostic criteria of IPAF, were divided into two groups: pirfenidone group (n=81) and non-pirfenidone group (n=103). Patients in the pirfenidone group had a lower forced vital capacity (FVC%, P< 0.001) and a lower diffusion capacity for carbon monoxide (DLCO%, P=0.003). The pirfenidone group exhibited a greater increase of FVC% at 6 (P=0.003), 12 (P=0.013), and 24 (P=0.003) months. After adjustment for sex, age, UIP pattern, baseline FVC% and DLCO%, patients in the pirfenidone group continued to show a greater improvement in FVC% (χ2 (1) =4.59, P=0.032). Subgroup analysis identified superior therapeutic effects of pirfenidone in patients with dosage > 600 mg/day (P = 0.010) and medication course > 12 months (P = 0.007). Besides, the pirfenidone group had a lower prednisone dose than the non-pirfenidone group after 12 months of treatment (P=0.002). Moreover, 17 patients (19.32%) experienced side effects after taking pirfenidone, including one case of anaphylactic shock.Conclusions: Pirfenidone (600-1,800 mg/day) might help improve FVC, with an acceptable safety and tolerability profile in IPAF patients.