Risk of cardiovascular events in patients at optimal values for combined lipid parameters

Current prevention guidelines support efforts to achieve optimal high-density lipoprotein (HDL-C) and triglyceride (TG) values, in addition to low-density lipoprotein (LDL-C) in order to reduce cardiovascular (CV) events. The study objective was to evaluate the risk of CV events in patients attaining versus not attaining combined (LDL-C, HDL-C, and TG) optimal lipid values.

This retrospective cohort analysis was conducted using a 1.1 million member managed care database. Eligible patients had a full lipid panel between 10/1/99 and 9/30/00, were naive to lipid therapy, and had health plan eligibility 12 months pre- and post-index (baseline) lipid laboratory value. Optimal lipid values (LDL-C, HDL-C, and TG) were established using the National Cholesterol Education Program Adult Treatment Panel (NCEP ATP III) guidelines, and patients were placed into one of four groups: none, one, two, or three lipid components non-optimal at baseline. The presence of cardiovascular risk, disease, and events were determined by selected International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9 CM) and Current Procedural Terminology (CPT codes). The definition of a CV event included: diagnosis of ischemic heart disease, peripheral arterial disease, stroke/TIA, or revascularization procedure. Odds ratios (OR) for a CV event associated with attainment of each optimal lipid fraction were determined by multivariate logistic regression. The study cohort included 30,348 patients, with a mean follow-up of 27 +/- 8 months. Mean age was 66 +/- 12 years; 16,549 (54%) were male; and 17,289 (57%) patients had coronary heart disease (CHD) or CHD risk equivalent. There were 5955 CV events that occurred in 4059 (13%) study patients. The presence of a single non-optimal lipid value slightly increased CV event risk [OR: 1.06; 95% CI: 0.95-1.18], whereas two or all three non-optimal lipid values significantly increased the risk of a CV event [OR: 1.22; 95% CI: 1.08-1.37; and 1.45; 95% CI: 1.24-1.68, respectively].

As with all large observational databases there are potential limitations including: patient selection bias (e.g., more interventions in patients with greater illness, lack of mortality data, and frequency of lipid monitoring), unknown confounding variables, and potential coding errors.

Not attaining optimal combined lipid values, independently and significantly, increased the risk of CV events in this large at-risk population with approximately 68,283 patient years of follow-up. The combination of non-attainment of optimal LDL-C with non-attainment of optimal HDL-C or TG values, or both, increased the adjusted risk of CV events by 22-45%. Thus, therapeutic strategies should focus on assessment and management of multiple lipid abnormalities, and not on single lipid risk factor modification.