Effect of Serum Cholesterol on Long-Term Coronary, Cardiovascular, and All-Cause Mortality
Effect of Serum Cholesterol on Long-Term Coronary, Cardiovascular, and All-Cause Mortality
abstract & commentary
Synopsis: High serum cholesterol levels in young adulthood carry a higher risk for CHD later in life.
Source: Stamler J, et al. JAMA 2000;284:311-318.
It has been consistently reported that an elevated serum cholesterol level is a significant risk factor for the development of coronary artery heart disease (CHD) and the other major cardiovascular diseases (CVDs).1-3 The relationship has been demonstrated to be continuous, graded, extremely strong, predictive, and independent of other risk factors. Many randomized controlled trials in middle-aged and older individuals have clearly demonstrated that effective, sustained reduction of serum cholesterol levels by dietary measures and/or pharmacologic means have been effective in reducing CHD and CVD risk.2,3
Stamler and associates from Northwestern University Medical School recognized that long-term prospective data studying the effects of baseline cholesterol levels and risk of CHD and CVD in younger men were quite limited. They, therefore, studied three cohorts of young men who were not afflicted with either diabetes mellitus or a history of myocardial infarction by obtaining baseline serum cholesterol level measurements. A total of 11,017 men aged 18-39 years were screened from 1967 to 1973 for the Chicago Heart Association Detection Project in Industry. A second cohort of 1266 men aged 25-39 years were examined in the Peoples Gas Company Study and the third cohort consisted of 69,205 men aged 35-39 years who were screened for the Multiple Risk Factor Intervention Trial (MRFIT). Men in all three cohorts with unfavorable serum cholesterol levels (> 200 mg/dL) had strong gradients of relative mortality risk. Men with serum cholesterol levels greater than 240 mg/dL had a CHD mortality risk that was 2.15-3.63 times greater than the control group and their CVD mortality was 2.10-2.87 times greater; finally, their all-cause mortality was increased by 1.31-1.49 more than the control group. Men with favorable baseline serum cholesterol levels had an estimated longer life expectancy of 3.8-8.7 years.
COMMENT by Harold L. Karpman, MD, facc, facp
The study by Stamler et al provides robust data that clearly confirmed and re-enforced previous reports4,5 that high serum cholesterol levels in young adulthood carries a higher risk for CHD later in life and that elevation of serum cholesterol (or, more specifically, low-density lipoprotein [LDL] cholesterol) appears to be a prime atherogenic agent, which causes coronary arterosclerosis to progress more rapidly throughout young adulthood.6
Some have argued that cholesterol testing in the younger age groups is not cost effective because relatively few young people with elevated serum cholesterol levels would be identified by early lipid testing and, besides, physicians are too busy with acute care medicine to be concerned with long-term prevention. On the other hand, Stamler et al have now clearly demonstrated that the prevalence of cholesterol levels more than 200 mg/dL is high in young American males, that 9% of young adults have total cholesterol levels of 240 mg/dL or higher, and finally, these young adults are particularly susceptible to the development of premature CHD.
Obviously, all patients whose serum cholesterol levels are elevated above 200 mg/dL should be counseled in lifestyle changes such as cigarette smoking cessation, avoidance of foods containing saturated fats, weight control, participating in a regular exercise program, and avoiding stress, regardless of their age. If nonpharmacologic measures are ineffective in controlling serum cholesterol levels, drugs may have to be used in order to bring the total serum cholesterol and LDL cholesterol levels down to appropriate values. Stamler et al’s study certainly lends support to the concept that serum cholesterol levels should be measured in male adults who are aged 20 years and older at least once every five years7 in order to avoid the long-term mortality due to CHD, which occurs in statistically significant numbers in one-third of young adults who have total cholesterol levels exceeding 200 mg/dL.
References
1. Stamler J. Lectures on Preventive Cardiology. New York, NY: Grune & Stratton; 1967.
2. JAMA 1993;269:3015-3023.
3. Stamler J, et al. JAMA 1999;282:2012-2018.
4. Anderson KM, et al. JAMA 1987;257:2176-2180.
5. Klag MJ, et al. N Engl J Med 1993;328:313-318.
6. McGill HC Jr., et al. Arterioscler Thromb Vasc Biol 1997;17:95-106.
7. National Cholesterol Education Program. Circulation 1994;89:1333-1445.
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