High deductible health plans (HDHP) are associated with high levels of patient cost-sharing and are becoming increasingly used in the United Status as a means of reducing healthcare utilization and spending. Our objective is to determine whether HDHP enrollment is associated with a change in adherence to evidence-based medications to treat cardiovascular risk factors and whether such changes vary based on race/ethnicity or socioeconomic status.
Methods and Results:
We conducted a retrospective cohort study using an interrupted time series with concurrent control group design among beneficiaries of Aetna—a national commercial insurer. We included 14 866 patients who filled prescriptions for medications to treat hypertension, high cholesterol, or diabetes mellitus between 2009 and 2014 and who switched from a traditional plan into an HDHP and 14 866 controls who did not switch to an HDHP matched based on calendar time, medication class, race/ethnicity, socioeconomic status, and propensity score. We were specifically interested in evaluating 4 prespecified subgroups based on race/ethnicity (white versus nonwhite) and socioeconomic status (higher versus lower). The main outcome was medication adherence as measured by proportion of days covered. The overall cohort had an average age of 53 years, and 44% were women. Baseline adherence was the lowest in the nonwhite patient group. Switching to an HDHP was associated with a decrease in the level of adherence of 5 percentage points across all 4 subgroups (change in level, −5.0%; 95% CI, −5.9% to −4.0%; P<0.0001).
HDHP enrollment was associated with a reduction in adherence to medications to treat cardiovascular risk factors. The magnitude of this effect did not vary based on race/ethnicity or socioeconomic status. Because racial/ethnic minorities have lower rates of medication adherence, future studies should evaluate whether HDHP-associated changes in adherence have greater clinical consequences for these patients.