Abstract 64: High Adherence to Colesevelam HCI Associated with Lower Risk of Major Cardiovascular Events

Abstract

Introduction: Medication adherence is a challenge in chronic disease management. Poor medication adherence may lead to suboptimal health outcomes for patients and negative economic impact on healthcare resources. Hypothesis: High adherence to colesevelam is associated with lower risk of major cardiovascular events of acute myocardial infarction (AMI) and stroke, among hyperlipidemia and/or type 2 diabetes mellitus (T2DM) patients newly treated with colesevelam. Methods: Thomson Reuters Marketscan 2007-2010 Commercial and Medicare databases including inpatient, outpatient and pharmacy claims were utilized for this study. The first colesevelam prescription fill date during this period was identified as the index date. The study sample consisted of hyperlipidemia and/or T2DM patients initiating colesevelam, with at least 6 months continuous enrollment before and after the index date. Adherence to colesevelam was measured as Medication Possession Ratio (MPR), calculated as total days of supply during one-year period after the index date (adherence cohort assignment period (ACAP)) divided by 365. Patients were assigned to one of three adherence cohorts (High: MPR≥0.8, medium: 0.5≤MPR<0.8, low: MPR<0.5.). The outcome was the time to the first hospitalization with a primary diagnosis for AMI or stroke during the follow up period, which began at the end of ACAP and continued to the end of the enrollment period or December 31, 2010, whichever occurred first. Association of colesevelam adherence and the outcome was examined by multivariate Cox regression, adjusting for patient demographics, baseline comorbidities, concomitant medications, and AMI or stroke during ACAP. Results: A total of 31,017 patients met the inclusion criteria and were included in the analysis, of which 5,696 (18.4%), 4,643 (15.0%), 20,678 (66.7%) were high, medium and low adherence, respectively. As compared to the low adherence group, the high adherence group was older, had more males, had more baseline cardiovascular risk factors, and had greater use of concomitant medications. Compared to patients with low adherence, high adherence patients were about 41% less likely to experience AMI or stroke hospitalization during the follow up period (Hazard Ratio: 0.59; 95% CI, 0.41 - 0.84, P=0.004). Other factors associated with significantly lower risk of AMI or stroke hospitalization included female gender, younger age, absence of baseline transient ischemic attack or coronary heart disease, absence of concomitant use of aliskiren, insulin or metformin, and absence of AMI or stroke during ACAP. Conclusions: High adherence to colesevelam was significantly associated with lower risk of major CV events (AMI and stroke) among hyperlipidemia and/or T2DM patients. The finding suggests that interventions to improve adherence to colesevelam in these patients may have long-term cardiovascular benefits.