The role of pirfenidone in the treatment of interstitial pneumonia with autoimmune features

Objective No approved pharmacotherapies are available for patients with interstitial pneumonia with autoimmune features (IPAF). 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 analysed 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, U1P pattern, baseline FVC% and DLCO%, patients in the pirfenidone group continued to show a greater improvement in FVC% (chi(2) (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 (1932%) experienced side effects after taking pirfenidone, including one case of anaphylactic shock. Conclusion Pirfenidone (600-1,800 mg/day) might help improve FVC, with an acceptable safety and tolerability profile in IPAF patients.