Association of State Insulin Out-of-Pocket Caps With Insulin Cost-Sharing and Use Among Commercially Insured Patients With Diabetes: A Pre–Post Study With a Control Group: Annals of Internal Medicine: Vol 0, No 0
Background: Twenty-five states have implemented insulin out-of-pocket (OOP) cost caps, but their effectiveness is uncertain. Objective: To examine the effect of state insulin OOP caps on insulin use and OOP costs among commercially insured persons with diabetes. Design: Pre–post study with control group. Setting: Eight states implementing insulin OOP caps of $25 to $30, $50, or $100 in January 2021, and 17 control states. Participants: Commercially insured persons with diabetes and insulin users younger than 65 years. Subgroups of particular interest included members from states with insulin OOP caps of $25 to $30, enrollees with health savings accounts (HSAs) that require high insulin OOP payments, and lower-income members. Measurements: Mean monthly 30-day insulin fills and OOP costs. Results: State insulin caps were not associated with changes in insulin use in the overall population (relative change in fills per month, 1.8% [95% CI, −3.2% to 6.9%]). Insulin users in intervention st