OBJECTIVES: To examine the relationship between adherence to colesevelam and risk of major cardiovascular events among hyperlipidemia and/or type 2 diabetes mellitus (T2DM) patients newly treated with colesevelam. METHODS: The study sample consisted of hyperlipidemia and/or T2DM patients in MarketScan database who newly initiated colesevelam with at least 6 and 12 months continuous enrollment prior- and post- drug initiation date in 2007-2010, respectively. Adherence to colesevelam was measured as Medication Possession Ratio (MPR), calculated as total days of supply during a one-year period after drug initiation 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