Lowering blood total cholesterol: a meta-analysis and policy statement
ACP J Club. 1993 July-Aug;119:4. doi:10.7326/ACPJC-1993-119-1-004
Canadian Task Force on the Periodic Health Examination. Periodic health examination, updateLowering the blood total cholesterol level to prevent coronary heart disease. Can Med Assoc J. 1993 Feb 15;148:521-38.
To make recommendations for the screening and management of hypercholesterolemia during the periodic health examination in asymptomatic patients.
Articles were identified through a MEDLINE search for the years 1966 to 1991, using the main MeSH heading cholesterol and the subheadings complications, diagnosis, drug therapy, epidemiology, prevention and control, and therapy. Additional studies were identified by bibliographic review of retrieved articles and recent review articles.
Articles that emphasized screening and treatment were reviewed. Primary prevention single-factor intervention studies were selected if their aim was to reduce the incidence of coronary heart disease, primarily among asymptomatic, middle-aged men, through reduction of serum cholesterol levels. The quality of studies was assessed according to standard methodologic criteria.
6 trials were identified: 4 drug trials and 2 dietary trials in which polyunsaturated fatty acids were substituted for saturated fatty acids. The Mantel-Haenszel method was used to evaluate the effect of cholesterol lowering. Only data for men were considered in the analysis.
The pooled results yielded a reduction in the number of nonfatal cardiac events in the treatment group (odds ratio [OR] 0.74, 95% CI 0.64 to 0.85) and a slight decrease in the number of cardiac deaths (OR 0.90, CI 0.71 to 1.14). These benefits were offset by an increase in deaths from noncardiac causes (OR 1.19, CI 1.03 to 1.39), which resulted in a net insignificant increase in the overall death rate. Cholesterol lowering was associated with an increase in violent deaths (OR 1.78, CI, 1.17 to 2.72), gallbladder disease (OR 1.69, CI 1.28 to 2.23), and cancer deaths (OR 1.41, CI 1.05 to 1.89).
Cholesterol lowering was associated with a reduction in the number of nonfatal cardiac events in asymptomatic, middle-aged men. This benefit was offset by increases in the rate of death from noncardiac causes, violent deaths, cancer deaths, and events of gallbladder disease. Expert opinion recommended case finding through repeated measurements of nonfasting blood total cholesterol in men 30 to 59 years of age. Otherwise, clinical judgment was advised to decide on screening and treatment for individual cases.
Source of funding: Not stated.
For article reprint: Health Services Directorate, Health Services and Promotion Branch, Department of National Health and Welfare, Tunney's Pasture, Ottawa, Ontario K1A 1B4, Canada.
The hypothesis that increased blood cholesterol levels are causally related to an increased risk for coronary heart disease (CHD) is now firmly established. Primary and secondary prevention studies (studies in healthy persons and studies in patients with known disease, respectively) have shown that cholesterol lowering, by either dietary or pharmacologic means, can reduce the incidence of coronary events. The increase in noncardiac deaths, however, negates any overall effect on mortality.
Screening for CHD by measuring total cholesterol levels is advocated by some because it is widely available, inexpensive, and the most extensively studied lipid risk factor. Total cholesterol, however, is a weak predictor for CHD in an individual patient, calling it into question as a universal detection method. Other lipid components such as high-density lipoprotein cholesterol, apolipoproteins, and lipoprotein(a) are additional potent coronary risk factors that may be able to better predict CHD events.
Despite these concerns, the decrease in coronary events with cholesterol lowering has led the Canadian Task Force to recommend nonfasting blood total cholesterol levels to screen for CHD risk in men between 30 and 59 years of age. Because not enough information was available on other patient groups, screening of elderly persons and female patients was left to the discretion of the examining physician. My preference is to consider measuring a full lipid profile in patients who have other significant risk factors for CHD.
Matthew J. Sorrentino, MD
University of Chicago Chicago, Illinois, USA