Comparison of weight in middle age, weight at 18 years, and weight change between, in predicting subsequent 14 year mortality and coronary events: Caerphilly Prospective Study

Objective-The prevalence of obesity is increasing in many European countrie s and in the United States. This report examines the mortality and morbidit y associated with being overweight and obese in the Caerphilly Prospective Study and the relative effects of weight in middle age and self reported we ight at 18 years. Design-All men aged 45 to 59 years from the town of Caerphilly, South Wales and outlying villages were identified and 2512 men were examined for the f irst time between 1979 and 1983. Men were asked to recall their weight at 1 8 years of age (when the majority had been examined for National Service) s o that weight then, weight at screening, and the difference could be relate d to their 14 year follow up from screening. A total of 2335 men could reca ll their weight at 18 years. By 14 years of follow up from screening 465 me n had died and 382 had had coronary events. Results-Mean body mass index in men who reported their weight at 18 years w as 22.3 (SD 2.8) kg/m(2) and only 41 of these men (1.8%) were classified as obese tinder greater than or equal to 30 kg/m(2)). The index did not; pred ict all cause mortality when examined by quintile. For major ischaemic hear t disease (non-fatal or fatal ischaemic heart disease) the relative odds wa s 1.73 (95% CI 1.21, 2.48) in the top fifth of the distribution (body mass index greater than or equal to 24.2 kg/m(2)) compared with the bottom fifth (body mass index <20.1 kg/m(2)). In men with an index greater than or equa l to 30 kg/m(2) however, the relative odds were 2.03 (95% CI, 1.03, 4.01) f or all cause mortality and 2.17 (95% CI, 1.08, 4.34) for major ischaemic he art disease, adjusted for age, smoking habit and social class. When men wer e recruited to the study, from 1979 to 1983; the mean body mass index had i ncreased to 26.2 (SD 3.6), a mean increase of 3.9 kg/m(2) or 11.2 kg; 299 m en (12.1%) were classified as obese and showed significantly increased rela tive odds of both all cause mortality (1.53 (95% CI 1.14, 2.06) and major i schaemic heart disease (1.55 (95% CI 1.13, 2.11)), adjusted for age, smokin g habit and social class relative to the non-obese men. The effect of gain in weight from 18 years to recruitment was also examined; all cause mortali ty showed highest mortality in the fifth of the distribution who experience d weight loss or minimal weight gain. For major ischaemic heart disease an inconsistent, weak trend was shown, the relative adds rising to a maximum o f 1.26 (0.89, 1.80) in the top fifth of weight gain compared with the botto m fifth. Weight gain showed strong associations with potential cardiovascul ar risk factors measured at recruitment; insulin, triglyceride, glucose, di astolic and systolic blood pressure and high density lipoprotein-cholestero l. Conclusions-Body mass at 18 years of age: of 30 kg/m(2) or more conferred i ncreased risk for all cause mortality and major ischaemic heart disease dur ing 14 years of follow up of men aged 45 to 59 years. By the baseline exami nation the prevalence of obesity (body mass index greater than or equal to 30) had increased from 1.8% to 12.1%; obese men also showed an excess risk of major ischaemic heart disease and overall mortality, but these risks wer e lower than those predicted from 18 years of age. Weight gain was strongly associated with smoking habit, the greatest weight gain being among ex-smo kers and the least among light smokers. Weight: gain from. 18 years of age to baseline examination showed little relation with subsequent mortality an d risk of major ischaemic heart disease when adjusted for age, smoking habi t and social class. The lowest mortality rate occurred in the "fifth'" of m en who gained a mean weight of 16.1 kg. Weight gain is closely associated w ith some adverse cardiovascular risk factors; in particular with iasulin, t riglyceride, glucose and diastolic blood pressure.