Pharmacy Subscription Program and Medication Refills, Days' Supply, and Out-of-Pocket Costs.

Importance: Medication nonadherence imposes high morbidity, mortality, and costs but is challenging to address given its multiple causes. Subscription models are increasingly used in health care to encourage healthy behaviors; in January 2023, Amazon Pharmacy launched RxPass, a subscription program offering Amazon Prime members (hereafter, company members) in 45 states access to 60 common generic medications for a flat $5 monthly fee.

Objective: To evaluate the associations of program enrollment with medication refills, days' supply, and out-of-pocket costs.

Design, Setting, And Participants: In this retrospective, population-based cohort study, a difference-in-differences approach with doubly robust estimation was used to assess outcomes 6 months before and after program enrollment, compared with a contemporaneous control group (study period included July 24, 2022, to January 24, 2024). Participants were younger than 65 years, company members, and not enrolled in Medicare or Medicaid. Exposure individuals were enrolled in the program in the first 6 months of program launch. Control individuals resided in the 5 states where the program was not available but who clicked on the enrollment webpage in the first 6 months of program launch.

Exposure: Subscription program enrollment.

Main Outcomes And Measures: The primary outcome was the number of days' supply of medications on the subscription program list per person per month (PPPM). Secondary outcomes were the number of prescription refills and out-of-pocket costs of medications on the program list, including program subscription costs, PPPM.

Results: After propensity score weighting, there were 5003 enrollees (mean [SD] age, 45.9 [11.1] years; 2076 female [41.5%]) and 5137 controls (mean [SD] age, 45.8 [11.1] years; 2116 female [41.2%]). The program was associated with an increase in days' supply of 10.39 days PPPM (95% CI, 10.29-10.48 days PPPM), a 27% increase, an increase in prescription refills of 0.19 PPPM (95% CI, 0.19-0.19 refills PPPM), a 29% increase, and a decrease in out-of-pocket spending by $2.35 PPPM (95% CI, $2.37-$2.33 PPPM), a 30% decrease.

Conclusions And Relevance: In this cohort study, program enrollment was associated with increased medication refills and total days' supply and reduced out-of-pocket costs. Future research should investigate the potential cognitive and/or behavioral mechanisms by which subscription programs encourage healthy behaviors and whether the results could be replicated among other pharmacies or cohorts.