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.