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.