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Some people are at very low risk from heart disease

BMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7224.1522c (Published 11 December 1999) Cite this as: BMJ 1999;319:1522
  1. Scott Gottlieb
  1. New York

    Individuals at the lowest risk from three major risk factors for cardiovascular disease are significantly less likely to die from myocardial infarction or stroke than those at average risk, according to an analysis of the results of two long term studies.

    The risk factors considered were lipid concentrations, blood pressure, and cigarette use (JAMA 1999;282:2012-8).

    Lead author Jeremiah Stamler, of Northwestern University Medical School, Chicago, and colleagues, analysed data from five groups of patients who participated in two long term studies of cardiovascular and non-cardiovascular mortality and life expectancy—the multiple risk factor intervention trial and the Chicago Heart Association detection project in industry.

    A total of 72 144 men aged 35 to 39 years and 270 671 men aged 40 to 57 participated in the risk factor intervention trial. Information was available from three groups in the heart association trial of 10 025 men aged 18 to 39 years, 7490 men aged 40 to 59 years, and 6229 women aged 40 to 59 years.

    Among the 366 559 people who participated in the studies, the death rate from coronary heart disease was about 80% lower overall among the middle aged adults who had been classed as being at low risk compared with those of average risk, according to the authors.

    All five low risk groups had significantly lower mortality from congestive heart disease and cardiovascular disease than age matched individuals who had raised concentrations of cholesterol or high blood pressure or who smoked cigarettes.

    In previous studies of the relation between major risk factors for cardiovascular disease, the benefits of being at low risk were estimated statistically because there were too few participants for risk to be measured satisfactorily. In this case, the large, long term studies permitted estimates of the risk factors to be made on the basis of observed mortality.

    Between 4.8% and 9.9% of all participants were considered to be at low risk for cardiovascular disease and coronary heart disease.

    Participants were classed as being at low risk if the concentration of cholesterol in their blood was less than 200mg/dl, if their systolic blood pressure was less than 120 mm Hg and their diastolic blood pressure was less than 80 mm Hg, and if they did not smoke currently. All participants with a history of diabetes, myocardial infarction, or, in three of the five cohorts, electrocardiographic abnormalities, were excluded from the studies.

    The death rate from coronary heart disease was much lower for those in the low risk groups among both African Americans and white Americans, irrespective of socioeconomic status. Mortality was between 86% and 92% lower for low risk, young adult men aged 18 to 39 and 77% to 79% lower for low risk, middle aged adults aged 49 to 59 years.

    In addition, there were no deaths from stroke in the two groups of young adults classed as low risk. Among middle aged participants classed as low risk, the age adjusted death rate from stroke was 52% to 76% lower.

    Death from all causes was consistently lower for those in the low risk group compared with other participants: 50% to 58% lower among the four cohorts of men and 40% for the single cohort of women.

    The estimated longer life expectancy for members of low risk groups compared with other participants ranged from a low of 5.8 years for women aged 40 to 59 years in the Chicago Heart Association study to 9.5 years for men aged 18 to 39 years in the same study.

    The estimated longer life expectancy for the other low risk groups was 6.3 years for men aged 35 to 39 years in the risk factor intervention trial, 5.9 years for men aged 40 to 57 in the same trial, and 6.0 for men aged 40 to 59 in the heart association trial.

    “These findings are relevant for the national effort to end the coronary heart disease and cardiovascular disease epidemic,” Dr Stamler said. “A population-wide strategy is critical to prevent and reduce the magnitude of all the major risk factors, so that a substantial increase is achieved in the proportion of people at low risk,” he said.

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