ABSTRACT: Purpose:The aim of this study was to investigate real-world patient characteristics, medication use, and health care resource utilization (HCRU) and costs among patients with clinical atherosclerotic cardiovascular disease (ASCVD) as defined by 2013 American College of Cardiology/American Heart Association (ACC/AHA) guidelines, to examine burden of disease and unmet needs, such as potential undertreatment. Patients and methods:This retrospective cohort study utilized a nationally representative managed care database to identify newly diagnosed ASCVD patients between January 1, 2007, and November 30, 2012 (index = first ASCVD diagnosis date) in the USA. Patients had ?12-month pre-index (baseline) and ?12-month post-index (follow-up) health plan enrollment and no baseline lipid-lowering medication (LLM). Patient characteristics, LLM utilization patterns, HCRU, and costs were examined for all patients and by subgroups based on LLM use pattern and/or follow-up low-density lipoprotein cholesterol (LDL-C) levels. Results:A total of 128,017 ASCVD patients were identified with a mean (SD) age of 59 (13) years, 43.1% female, and 48.8% with ?36-month follow-up. Within 12-month follow-up, 10.6% had high-intensity statins and 56.9% had no LLM fills. Baseline mean (SD) all-cause costs were $8,852 ($25,608). At 12-month follow-up, mean (SD) all-cause and ASCVD-related costs were $31,443 ($54,040) and $20,289 ($45,159), respectively. The 36-month analyses showed similar distributions. Multivariable analyses showed that age, gender, region, health insurance type, baseline comorbidities, baseline use of specific medications, baseline lipid profiles, and index ASCVD type were significantly associated with all-cause and ASCVD-related health care costs. Conclusion:Patients have nonoptimal treatment for ASCVD and substantial HCRU and costs associated with residual risk. Unmet needs and cost burdens of ASCVD patients merit additional investigation.