Body mass index in early and mid-adulthood, and subsequent mortality: a historical cohort study

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Abstract
BACKGROUND: The aim of this study was to investigate the associations between body mass index (BMI) in early and mid-adulthood, and BMI change between these ages, and mortality. METHODS: Historical cohort study of 629 men, who had height and weight measured at the Student Health Service of the University of Glasgow in 1948–1949 (median age 22?y) and who reported their weight in a postal questionnaire in 1963–1966 (median age 38?y). The participants were followed up until April 2002 (mean follow-up: 35?y). During this time, 124 men died, 68 of cardiovascular disease (CVD) and 33 of cancer. FINDINGS: Mean BMI increased from 21.4?kg/m2 (standard deviation (s.d.): 2.2?kg/m2) in early adulthood to 24.2?kg/m2 (s.d.: 3.0?kg/m2) in mid-adulthood. All-cause mortality was associated with being overweight (BMI≥25?kg/m2) at age 22 but not at age 38, adjusted hazard ratio (HR): 1.85 (95% confidence interval (CI) 1.09–3.13) and 1.05 (95% CI: 0.73–1.52), respectively. BMI at age 22?y was more strongly associated with CVD mortality than was BMI at age 38?y, adjusted HR22?y: 2.41 (95% CI: 1.26–4.60) and HR38?y: 1.33 (95% CI: 0.82–2.16). There was no clear relationship between cancer mortality and BMI at either age: HR22?y: 0.68 (95% CI: 0.16–2.91), HR38?y: 0.90 (95% CI: 0.44–1.84), although relatively few men died of cancer in the follow-up period. Similar patterns were seen for obesity (BMI≥30?kg/m2) as for being overweight. Analyses of weight patterns indicated particularly detrimental effects of overweight persisting from early to mid-adulthood. CONCLUSIONS: BMI in early adulthood is positively related to CVD mortality in later life in men. The risk associated with early adulthood adiposity appeared to be greater than that in mid-adulthood. We did not demonstrate an association between weight gain and later mortality. These results reinforce the need to stem the obesity epidemic in children and young adults.