Effect of prescription copayments on medication compliance and hospitalizations in commercially insured patients with heart failure

While pharmaceutical copayments are effective in containing system-level expenditures, the increased financial burden on patients may decrease medication compliance. Though many studies have focused on the effects of copayments on utilization, fewer have simultaneously examined copayments, compliance, and clinical outcomes, especially within heart failure patients. The rising prevalence and economic burden of heart disease underscores the need to research copayment effects on compliance and outcomes in this population. The primary objective of this research was to estimate the effects of angiotensin converting enzyme (ACE) inhibitor, beta-adrenergic blocker and diuretic prescription copayment levels on medication compliance and hospitalizations in commercially insured heart failure patients. The secondary objective was to measure whether medication noncompliance mediates the association between copayment levels and hospitalizations. Heart failure patients were identified from the Integrated Health Care Information Solutions, Inc. database, containing a sample of United States commercially insured individuals between 1997 and 2005. Refill copayments were defined in categorical ranges, medication compliance by the Medication Possession Ratio, and hospitalizations by the presence of all-cause, cardiovascular specific or heart failure specific inpatient claims. This retrospective cohort study used ordinary least squares, random effects, and fixed effects regressions to estimate the effect of copayment level on compliance and logistic regressions to estimate the risk of hospitalizations conditional upon prescription copayment level. Mediation models were used to explore causal pathways between copayment level, medication compliance, and hospitalization. Beta blocker and diuretic refills with higher copayment levels were associated with up to a 9% and 21% decrease in medication compliance, respectively. In regards to clinical outcomes, higher diuretic copayments were associated with up to 1.4, 2.5, and 3.8 times the risk of all-cause, cardiovascular, or heart-failure specific hospitalization, respectively. Medication compliance did not mediate the association between copayment level and hospitalization. Results suggest that higher beta blocker and diuretic copayments are associated with decreased compliance in privately insured heart failure patients. Furthermore, higher diuretic copayments are associated with increased risk of hospitalization. Estimates need to be interpreted with caution given the absence of a control group. Future studies need to be conducted to determine the true causal nature of these associations