Data from two long-term studies show that people with the most favorable levels of all three major coronary risk factors (blood cholesterol, blood pressure, and cigarette use) experienced markedly lower death rates from heart attack and stroke, as well as notably increased life spans.
A report on the two studies, the Multiple Risk Factor Intervention Trial (MRFIT), and the Chicago Heart Association Detection Project in Industry (CHA), appears in the December 1, 1999 issue of the Journal of the American Medical Association.
"A nearly 80 percent lower rate of coronary heart disease deaths among low-risk middle aged adults compared with those of average risk is an astounding difference in the rates of heart and cardiovascular disease" said Dr. Claude Lenfant, Director of the National Heart, Lung, and Blood Institute (NHLBI). "Unfortunately, only a small percent of adults is at low risk. Our challenge for the 21st century is to prevent risk factors from developing in the first place by encouraging healthy behaviors early in life," added Dr. Lenfant.
MRFIT, a 16-year study funded by the NHLBI, a component of the National Institutes of Health, looked at two groups of men (ages 35-39 and ages 40-57) in 18 cities. CHA also studied two groups of men (ages 18-39 and ages 40-59), as well as one group of women (ages 40-59) in 84 Chicago companies and other organizations over a period of 22 years. CHA was co-funded by the American Heart Association and NHLBI.
Of the 366,559 people who participated in the two studies, just 5 - 10 percent in all groups were considered low risk for cardiovascular disease and coronary heart disease. Criteria for low risk in both studies included blood cholesterol level (<200mg/dl), systolic blood pressure ( 120mmHG)/diastolic blood pressure ( 80mmHG), not currently a smoker, and no history of diabetes or heart attack. In addition, for the three CHA groups, low-risk participants did not exhibit ECG abnormalities.
For both African Americans and whites, and irrespective of socioeconomic status, the findings show that the death rate from coronary heart disease (CHD) was much lower for low-risk groups than for other study participants; by 86 percent to 92 percent for low-risk young adult men (i.e., men ages 18-39), and by 77 percent to 79 percent for low-risk middle-aged adults (i.e., men and women ages 40-59). For low-risk adult men, deaths from CHD accounted for only 6 percent to 8 percent of all deaths versus 25 percent to 29 percent for other participants in the study.
There were no deaths from stroke in the two young adult low-risk groups. For the low-risk middle-aged groups, the age-adjusted death from stroke was lower by 52 percent to 76 percent compared to others. Death from all causes was consistently, markedly, significantly lower for low-risk versus others - by 50 percent to 58 percent for men and 40 percent for women. The estimated greater life expectancy for low-risk versus others ranged from 5.8 years to 9.5 years.
To arrange an interview with Dr. Jeremiah Stamler, the lead author of the report, please call Northwestern University Medical School, 312/503-8928.