OBJECTIVES: As new cystic fibrosis transmembrane conductance regulator modulators (CFTRm) continue to come to market and improve health in patients with cystic fibrosis (CF), CFTRm therapy adherence is increasingly more important to address. The goal of this research study was to examine the association between CFTRm therapy adherence and the outcomes of hospitalization and medical costs in CF patients using MarketScan commercial claims from 2019.

METHODS: MarketScan commercial claims from 2019 were used to calculate proportion of days covered (PDC). For outcome comparisons, patients were defined as adherent if they had a PDC > 80%. Patients were eligible for PDC calculation if they were adults (≥18 years), prescribed one of three CFTRm therapies (Kalydeco, Symdeko, Orkambi), and had one-year continuous enrollment in a health plan. Outcomes examined were CF-associated medical costs, bed days for those hospitalized, CFTRm pharmacy costs, and non-CFTRm medication costs.

RESULTS: A total of 598 patients met criteria for the study. The mean PDC for CF patients was 74.1%. The highest mean adherence was for Kalydeco (M=76.2%), followed by Symdeko (M=73.8%), and Orkambi (59.6%). Hospitalization of adherent patients (22.1%) was significantly lower than non-adherent patients (37.6%, p<.001). Total inpatient costs for adherent patients (M=$64,736) were lower, than non-adherent patients (M=$104,085, p=.06) but there was no significant difference in days hospitalized (Adherent M=13.3, Non-adherent M=15.7, p=.43). Finally, CFTRm pharmacy costs for adherent patients were higher than for non-adherent patients (P<.001), but there was no difference between non-adherent and adherent groups for associated medication pharmacy costs.

CONCLUSIONS: The results of this study suggest that adherence to CFTRm therapies may lower hospitalization rates and inpatient costs. Specialty pharmacies should consider implementing clinical patient support programs to aid in improving adherence.