Medication adherence of bisphosphonate weekly or monthly regimens in patients with osteoporosis using a nationwide large claims database

Bisphosphonate (BPN) therapy, which mainly targets osteoporosis, evolves rapidly, leaving patients and physicians with a substantial collection of BPN regimen options. In this study, we aimed to clarify BPN medication adherence between weekly and monthly regimens using a nationwide claims database in Japan. We analyzed 5,016 patients with a screening period of 3 months and a 12 month observation period who started using BPN. We used propensity score matching with baseline patient background after dividing the patients into two groups: weekly and monthly BPN users. Medication adherence was calculated using proportion days cover (PDC). A PDC of > 80% was 55.9% and 52.5% in monthly and weekly formulas, respectively, during the 12 months after initiating BPN treatment. PDC-based BPN medication adherence was higher in monthly regimens than in weekly regimens (66.3±34.0 vs. 64.1±36.8%). No differences were found in the proportion of patients with > 80% medication adherence between the monthly and weekly regimens after stratifying patient background using propensity score matching. Our clinical findings highlight the importance of closely monitoring BPN medication adherence, particularly during the initial year of therapy. Notably, half of the patients with osteoporosis exhibited low medication adherence. Therefore, prioritizing monthly regimens over weekly regimens is crucial to promote BPN adherence and ensure optimal treatment outcomes.