Colorado Insulin Copay Cap: Lower Out-Of-Pocket Payments, Increased Prescription Volume And Days’ Supply

In 2020, Colorado became the first state to cap out-of-pocket spending for insulin prescriptions, requiring fully insured health plans to cap out-of-pocket spending at 100 for a thirty-day supply. We provide the first evidence on the association of Colorado's Insulin Affordability Program with patient out-of-pocket spending, the amounts paid by plans per insulin prescription, and prescription filling. Using statewide claims data from the period 2018–21, we focused on the first two years that the copay cap law was in effect. We found that Colorado's Insulin Affordability Program was associated with significant reductions in out-of-pocket spending for insulin prescriptions, with the mean out-of-pocket payment per thirty-day supply falling nearly in half (from 62. 59 to 35. 64). Average plan payments increased slightly more (31. 39) than the decrease in out-of-pocket spending, as the total amount paid per prescription increased by about 1 percent. The average insulin user realized annual savings of 184, while the mean number of fills and the mean days' supply per year increased by 4. 2 percent and 11. 4 percent, respectively.