Association between nintedanib adherence trajectory and healthcare use among idiopathic pulmonary fibrosis patients

Background: Although inverse associations have been found between medication adherence and healthcare use and spending outcomes in many clinical settings, no studies to date have examined these relationships for patients with idiopathic pulmonary fibrosis (IPF) initiating nintedanib. We build on our prior study that used group-based trajectory modeling (GBTM) to compare inpatient hospitalization and medical care spending outcomes between groups of patients with different nintedanib adherence trajectories. Methods: This analysis used 100% Medicare data and included beneficiaries with IPF who initiated nintedanib during 10/01/2014–12/31/2018. The sample consisted of community-dwelling older adults (≥ 66 years) with continuous coverage in Medicare Parts A (inpatient care), B (outpatient care) and D (prescription drugs) for one year before (baseline) and after (follow-up) initiating nintedanib. Patients were assigned to the GBTM-derived adherence trajectory group closest to their own nintedanib adherence experience. All-cause and IPF-related hospitalization events and total medical spending were measured during the follow-up period. Unadjusted and adjusted regression models were estimated to compare outcomes between patients in different nintedanib adherence trajectories. Results: Among the 1,798 patients initiating nintedanib, the mean age was 75.4 years, 61.1% were male, and 91.1% were non-Hispanic white. The best-fitting GBTM had five adherence trajectories: high adherence, moderate adherence, high-then-poor adherence, delayed-poor adherence, and early-poor adherence. All-cause hospitalizations and total all-cause medical spending were higher among patients in the high-then-poor, delayed-poor and early-poor adherence trajectories than those in the high adherence trajectory. For example, adjusted total all-cause medical spending was $4,876 (95% CI: $1,470 to $8,282) higher in the high-then-poor adherence trajectory, $3,639 (95% CI: $1,322 to $5,955) higher in the delayed-poor adherence trajectory and $3,907 (95% CI: $1,658 to $6,156) higher in the early-poor adherence trajectory compared with the high adherence trajectory. IPF-related hospitalizations and medical care spending were higher among those in the high-then-poor adherence trajectory compared with those in the high adherence trajectory. Conclusions: Poor adherence to nintedanib was associated with all-cause hospitalizations and medical costs. Therefore, improved adherence programs, such as support programs, can be implemented to reduce economic burden.