Preventive drug lists lead to increased use of essential medications for diabetes

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For diabetic patients in high-deductible health plans (HDHPs), the introduction of preventive drug lists (PDLs)—with no copayments for preventive medications—is associated with lower out-of-pocket costs and increased use of essential medications, reports a study in Medical Care.

The researchers evaluated a natural experiment using data on commercially insured patients with diabetes enrolled in HDHPs (individual deductible at least $1000) linked to health savings accounts. Approximately 1750 patients in an intervention group were switched by their employers to PDL coverage. This meant that essential medications and supplies for preventing adverse outcomes of diabetes—including antidiabetic drugs, insulin, test strips, and blood pressure-lowering and cholesterol-lowering drugs—became available with no or limited cost sharing.

Patients switched to PDL coverage were propensity-matched to a control group of approximately 3350 patients enrolled in HDHPs with no PDL. Out-of-pocket costs for medications were compared between groups. Medication use was assessed in terms of pharmacy fills, converted to 30-day equivalents.

Patients who transitioned to PDLs saw a significant decrease in medication costs. The average saving was $621 per member per year: a 35% reduction. The reduction in out-of-pocket costs was associated with a sharp increase in the use of preventive medications: six additional refills per year, on average.

The increase in medication use was more than twice as large for lower-income patients: 6.6 refills per year, compared with 3.0 for higher-income patients. “Overall savings in out-of-pocket spending were much larger for patients with severe diabetes, primarily due to savings on insulin,” the researchers note.

A growing number of Americans are enrolled in HDHPs, with the goal of reducing unnecessary care while promoting higher-value care. However, deductibles, copayments, and other forms of cost sharing can adversely affect the use of needed medications for chronic diseases, including diabetes. To address this issue, some employers and insurers have introduced PDLs, exempting specific medications from deductibles and copayments.

The introduction of PDLs is associated with lower out-of-pocket costs for people with diabetes in HDHPs, leading to increased use of clinically essential medications. The increases in medication use appear “larger and potentially more important” in lower-income patients. The study appears as part of a special supplement to Medical Care, presenting new reports from the Natural Experiments for Translation in Diabetes 2.0 (NEXT-D2) Network [Ross-Degnan D, et al. Reduced cost-sharing for preventive drugs preferentially benefits low-income patients with diabetes in high deductible health plans with health savings accounts: A Natural Experiments for Translation in Diabetes (NEXT-D2) study. Med Care doi: 10.1097/MLR.0000000000001295].