Employers are increasingly purchasing "preventive drug list" (PDL) insurance plans that make cardiometabolic medications $0. PDL designs improve adherence, but effects on health outcomes are unknown. We analyzed 2004-2017 commercial health insurance claims using a large, national data set. The intervention group included 12,853 commercially-insured diabetes patients aged 12-64 years who experienced employer-mandated PDL switches; the control group included 12,989 matched counterparts whose employers offered no PDL. We defined the index date as the day the intervention group received the PDL, and matched controls had a contemporaneous index date. Both groups had a 1-year baseline and 1-year follow-up study period. We measured monthly rates of aggregated acute preventable diabetes complication episodes (e.g, hyperglycemic coma, angina, and pneumonia) presenting to (1) the outpatient setting or (2) the emergency department, observation, or inpatient settings ("high acuity") . We constructed cumulative interrupted time series plots of these two measures and conducted segmented regression analysis and marginal effects estimation. Low-income members were a subgroup of interest. Annual outpatient and high-acuity complication episodes decreased by -13.5% (-15.2%, -11.7%) and -13.9% (-15.3%, -12.5%) , respectively, in the PDL group relative to controls. Low-income PDL members also experienced decreased outpatient (-27.2% [-32.1%, -22.4%]) and high-acuity complication episodes (-4.4% [-6.5%, -2.4%]) . This rigorous, quasi-experimental study is the first to demonstrate that a value-based medication benefit is associated with improved health outcomes and reduced disparities. Employer adoption of PDLs thus represents a relatively expedient approach to improving health and equity, and our results support a strategy of incentivizing such targeted cost sharing reductions for vulnerable diabetes populations.


J.Wharam: None. F.Zhang: Research Support; GlaxoSmithKline plc. M.Lakoma: None. L.F.Garabedian: None. S.Argetsinger: None. D.Ross-degnan: None.



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