PROVIDENCE, RI — How did a copayment increase instituted Feb. 1, 2018, for beneficiaries covered by the retail or mail order Military Health System (MHS) pharmacy benefit affect medication use?
That issue was tackled in a recent study from Brown University School of Public Health. The researchers compared the effects in 2 cohorts in the 12 months before and after the copayment increase. Many of the patients had diabetes.
Eligible for inclusion in the study were MHS beneficiaries between 18 and 64 years old (MHS cohort) and MHS beneficiaries older than or equal to 65 years old with Medicare (Medicare cohort) and included participants with diabetes, hypertension and hypercholesterolemia.
The MHS cohort included 30,753, 46,965 and 59,783 nonunique persons with diabetes, hyperlipidemia and hypertension, respectively, in the intervention and control groups. In the Medicare cohort there were 45,977, 205,363 and 365,628 nonunique persons, respectively, with those conditions, the authors advised.
A comparison was made between those who obtained medications at military pharmacies ($0 copay) to those who experienced a copay increase. Defined as the outcome variable was any use of condition-specific medication. The results were published in the journal Medical Care.
The results indicated that the post-period mPDC differences for the MHS cohort were 0.02 (95% CI: 0.01, 0.03), 0.03 (95% CI: 0.02, 0.03) and 0.03 (95% CI: 0.01, 0.03) for the diabetes, hyperlipidemia and hypertension cohorts, respectively. The post-period mPDC differences for the Medicare cohort were 0.01 (95% CI: 0.01, 0.02), 0.03 (95% CI: 0.03, 0.04) and 0.01 (95% CI: 0.01, 0.02), respectively.
“The small (1-3 percentage point) copayment increases are unlikely to have had adverse clinical effects,” the researchers concluded. “Insurers and policymakers should understand that even small copayment increases can impact the use of clinically important medications and should carefully consider the tradeoffs.”
- Wilson IB, Gutman R, Lee Y, Dana BA, Hiris J, Zhang T, Thompson K, Gromadzki R, Shireman TI. Impact of a Pharmacy Copayment Increase on Medication Use in the Military Health System. Med Care. 2025 Oct 1;63(10):731-739. doi: 10.1097/MLR.0000000000002176. Epub 2025 Jul 1. PMID: 40730346.
