The effects of patient out‐of‐pocket costs on insulin use among people with type 1 and type 2 diabetes with Medicare Advantage insurance—2014–2018

Objective To identify the association between insulin out‐of‐pocket costs (OOPC) and adherence to insulin in Medicare Advantage (MA) patients. Data Sources and Study Setting The study is based on Optum Labs Data Warehouse, a longitudinal, real‐world data asset with de‐identified administrative claims and electronic health record data. Study Design Using descriptive and multivariable logistic regression analyses, we identified the likelihood of patients with diabetes having ≥60 consecutive days between an expected insulin fill date and the actual fill date (refill lapse) by OOPC, categorized by $0, >$0–$20 (reference), >$20–$35, >$35–$50, and > $50 per 30‐day supply. Data Collection/Extraction Methods The study included MA enrollees with type 1 or type 2 diabetes and prescription claims for insulin between 2014 and 2018. Principal Findings Those with average insulin OOPC per 30‐day supply >$35 or $0 were more likely to have an insulin refill lapse versus OOPC of >$0 to $20, with odds ratios ranging 1.18 (95% CI 1.13–1.22) to 1.74 (95% CI 1.66–1.83) depending on OOPC group and diabetes type. Conclusions Capping average insulin OOPC at $35 per 30‐day supply may help avoid cost‐related insulin non‐adherence in MA patients; efforts to address non‐cost barriers to medication adherence remain important.