Differences in Diabetic Prescription Drug Utilization and Costs Among Patients With Diabetes Enrolled in Colorado Marketplace and Medicaid Plans, 2014-2015

Abstract

Increasing prices of antidiabetic medications in the US have raised substantial concerns about the effects of drug affordability on diabetes care. There has been little rigorous evidence comparing the experiences of patients with diabetes across different types of insurance coverage. To compare the utilization patterns and costs of prescription drugs to treat diabetes among low-income adults with Medicaid vs those with Marketplace insurance in Colorado during 2014 and 2015. This cross-sectional study included diabetic patients enrolled in Colorado Medicaid and Marketplace plans who were aged 19 to 64 years and had incomes between 75% and 200% of the federal poverty level during 2014 and 2015. Data analysis was conducted from September 2020 to April 2021. Health insurance through Colorado Medicaid or Colorado's state-based Marketplace. Primary outcomes were drug utilization (prescription drug fills) and drug costs (total costs and out-of-pocket costs). The secondary outcome was months with an active prescription for noninsulin antidiabetic medications. An all payer claims database was combined with income data, and linear models were used to adjust for clinical and demographic confounders. Of 22 788 diabetic patients included in the study, 20 245 were enrolled in Medicaid and 2543 in a Marketplace plan. Marketplace-eligible individuals were older (mean [SD] age, 52.12 [10.60] vs 47.70 [11.33] years), and Medicaid-eligible individuals were more likely to be female (12 429 [61.4%] vs 1413 [55.6%]). Medicaid-eligible patients were significantly more likely than Marketplace-eligible patients to fill prescriptions for dipeptidyl peptidase 4 inhibitors (adjusted difference, -3.7%; 95% CI, -5.3 to -2.1; P < .001) and sulfonylureas (adjusted difference, -6.6%; 95% CI, -8.9 to -4.3; P < .001). Overall rates of insulin use were similar in the 2 groups (adjusted difference, -2.3%; -5.1 to 0.5; P = .11). Out-of-pocket costs for noninsulin medications were 84.4% to 95.2% lower and total costs were 9.4% to 54.2% lower in Medicaid than in Marketplace plans. Out-of-pocket costs for insulin were 76.7% to 94.7% lower in Medicaid than in Marketplace plans, whereas differences in total insulin costs were mixed. The percentage of months of apparent active medication coverage was similar between the 2 groups for 4 of 5 drug classes examined, with Marketplace-eligible patients having a greater percentage of months than Medicaid-eligible patients for sulfonylureas (adjusted difference, 5.3%; 95% CI, 0.3%-10.4%; P = .04). In this cross-sectional study, drug utilization across multiple drug classes was higher and drug costs were significantly lower for adults with diabetes enrolled in Medicaid than for those with subsidized Marketplace plans. Patients with Marketplace coverage had a similar percentage of months with an active prescription as patients with Medicaid coverage.