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

BACKGROUND: 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. METHODS/
RESULTS: 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]. LIMITATIONS: 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.
CONCLUSION: 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.