Adoption of the Antifibrotic Medications Pirfenidone and Nintedanib for Patients with Idiopathic Pulmonary Fibrosis

Rationale: In October 2014, the antifibrotic medications pirfenidone and nintedanib became the first medications approved by the U.S. Food and Drug Administration for use in patients with idiopathic pulmonary fibrosis (IPF). Since approval, there has been no nonregistry analysis of the real-world adoption of these medications in everyday clinical practice. Objectives: To evaluate the adoption, persistence, and out-of-pocket (OOP) costs of pirfenidone and nintedanib since their approval in the United States in 2014. Methods: A retrospective cohort analysis was performed by identifying privately insured and Medicare Advantage beneficiaries with IPF. We then split the patients into three cohorts: those who were untreated and those who filled a prescription for either pirfenidone or nintedanib between October 1, 2014, and July 31, 2019. The primary outcome was adoption of the medications. Secondary outcomes included medication persistence and prescription drug costs. Results: A total of 10,996 patients with IPF were identified in the data set. A minority of patients (26.4%) with IPF identified in the cohort had started either medication since approval in 2014, with the adoption of both medications being comparable at around 13.2%. Those receiving the medications were younger (72 vs. 73.9 yr; P < 0.0001) and healthier (3.9 vs. 4.9 comorbidities; P < 0.0001) than those not receiving treatment. Men were significantly more likely to receive treatment than woman (30.0% vs. 21.9%; P < 0.0001). Among treated patients, 42.8% discontinued the medications during the study period. Patients' OOP expenses per month were high for both drugs (mean, $397.51 for nintedanib; mean, $394.49 for pirfenidone). Conclusions: The adoption of both the antifibrotic medications in the United States in everyday practice has been low since approval and may be associated with the high OOP cost.