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Objectives
Few studies have examined the association between adiposity in early adulthood and later coronary heart disease (CHD). Further, whether the impact of early adiposity is mediated via adiposity in middle age or, if it exerts an independent effect, has yet to be tested. We examined these issues using extended follow-up of the Harvard Alumni Study.
Design
Cohort study of male University students who had a physical examination at college entry between 1914 and 1952 (mean age 18.4 years) when data on CHD risk factors including body mass index (BMI; weight, kg/height, m2), our measure of adiposity, were measured directly. Study participants were traced, mailed a health questionnaire in 1962/1966 (mean age 45.1 years) which included enquiries regarding self-reported height and weight, and were followed for subsequent mortality experience – with >99% completion – until the end of 1998. BMI was categorised into quartiles in the present analyses.
Setting
USA.
Participants
14 638 men enrolled in Harvard University in the given years, who completed the subsequent health questionnaire, and whose vital status could be ascertained.
Main Outcome Measure
CHD death.
Results
Over a maximum of 82.5 years of follow-up (median 56.5 years), there were 1401 deaths from CHD. Following adjustment for age and other CHD risk factors (cigarette smoking, physical activity, blood pressure) at college entry, relative to the lowest weight quartile (mean BMI = 18.7 kg/m2), there was an elevated risk of CHD mortality in men in the highest quartile (mean BMI = 25.0 kg/m2; hazards ratio 1.28, 95% CI 1.10 to 1.49) but not the intermediate groups. Following additional control for BMI in middle-age, this increased CHD risk in the highest quartile was eliminated (1.03; 0.87 to 1.21).
Conclusion
In this cohort, higher BMI in early adulthood was associated with an elevated risk of CHD mortality several decades later but this effect appeared to be entirely meditated via BMI in middle-age.