Lower Risk of Major Cardiovascular Events Associated with Adherence to Colesevelam HCI

Study ObjectiveTo examine the relationship between adherence to colesevelam and the risk of major cardiovascular events (acute myocardial infarction [AMI] and stroke) among patients newly treated with colesevelam. DesignRetrospective cohort study using administrative claims data. Data SourceMarketScan commercial and Medicare databases (2005-2011). PatientsA total of 42,549 adults with hyperlipidemia and/or type 2 diabetes mellitus who newly started colesevelam between January 1, 2005, and September 30, 2011, and who had continuous enrollment in employer-sponsored commercial health insurance or Medicare supplemental benefit plans for at least 6months before and 12months after the date of colesevelam initiation. Measurements and Main ResultsAdherence was measured as the proportion of days covered (PDC) by prescription claims for colesevelam during the 1-year period after the drug initiation date. Patients were assigned to one of three adherence cohorts: adherent, PDCof0.8 or more; partially adherent,PDCof 0.5-0.8; or nonadherent, PDCof less than0.5. The primary outcome was time to the first hospitalization with a primary diagnosis for AMI or stroke during the follow-up period. Association of colesevelam adherence with the primary outcome was examined by multivariate Cox regression models, adjusting for demographics, comorbidity, and concomitant drugs. A sensitivity analysis between propensity score-matched cohorts was conducted to compare the outcome between adherent and nonadherent groups. Of the 42,549 patients included in the analysis, 7968 (18.7%) were adherent, 6197 (14.6%) were partially adherent, and 28,384 (66.7%) were nonadherent. Compared with nonadherent patients, adherent patients were older, more likely to be male and from the Northeast or North Central regions of the United States, and had more cardiovascular risk factors and concomitant drugs. Controlling for patient demographic and clinical characteristics, adherent patients were about 43% less likely to experience an AMI or stroke hospitalization during the follow-up period compared with nonadherent patients (hazard ratio 0.57, 95% confidence interval[CI] 0.44-0.73, p<0.0001). Results of the sensitivity analysis using propensity score matching techniques were consistent. ConclusionAdherence to colesevelam was associated with lower risk of major cardiovascular events (AMI and stroke) among patients with hyperlipidemia and/or type 2 diabetes. Research to assess interventions to improve adherence to colesevelam and subsequently to evaluate the effects of these interventions on cardiovascular outcomes is warranted.