The Association between Deductibles and Cardiovascular Medication Adherence: A Retrospective Inception Cohort Study

Drug non-adherence in primary preventive cardiovascular therapy is one of the most important modifiable drivers of cardiovascular events. The effect of deductibles in healthcare cost-sharing plans (the amount that has to be paid for healthcare services before the insurance company starts to pay) on such non-adherence in a European setting is unknown. Therefore, we estimated the association between deductibles and the adherence to primary preventive antihypertensive and antihyperlipidemic medication.

Using the claims database of Menzis Health Insurer in the Netherlands, we applied ordered beta regression mixed modelling to estimate the association between deductibles and adherence taking several demographic and social-economic factors, repeated measurements and within-patient variation into account.

All in all, 106,316 patients starting primary preventive antihypertensive or antihyperlipidemic monotherapy were eligible for analysis. At index date, mean age of the study population was 58 years and 52% were male. Reaching the deductible limit and no need to pay for medication anymore increased the adherence [relative adherence ratio (RAR) 1.03, 95% confidence interval (95% CI): 1.00-1.05] for antihyperlipidemic therapy and 1.02 (95% CI: 1.00-1.04) for antihypertensive therapy. A larger deductible amount decreases the adherence of antihyperlipidemic and antihypertensive therapy (RAR 0.83; 95% CI: 0.69-1.00 and RAR 0.85, 95% CI: 0.74-0.98, respectively).

Independent of other risk factors for non-adherence, presence of deductibles in health insurance is associated with a small negative effect on the adherence to both primary preventive antihypertensive as well as antihyperlipidemic therapy. Further study is needed on the potential health-economic consequences.