Objective: To re-analyse the previously reported linear relation between Quetelet's body mass index (BMI) and mortality, among men from the Adventist Mortality Study after accounting for effects due to age at measurement of BMI, smoking history and race.
Design: Prospective cohort study. To specifically account for effects due to age at measurement of BMI, smoking history and race, our methodology includes: 1, computing hazard ratios for BMI quintiles from a proportional hazard regression, with 'time on study' as the time variable, and age at baseline as a covariate; 2, conducting separate analyses of middle-aged (age 30-54y) and older (age 55-74y) men; and 3, restriction of the analyses to never-smoking, non-Hispanic white males.
Subjects: 5062 men (age: 30-74 y, BMI: 14-44 kg/m2) from the Adventist Mortality Study.
Measurements: Subjects reported data on anthropometric, demographic, medical, dietary and lifestyle characteristics at baseline and were enrolled in mortality surveillance during a 26y study period (1960-1985).
Results: During the early years of follow-up (years 1-8, 9-14), we found some evidence of excess risk among the leanest men that was probably due to the effects of antecedent illness. During the later years of follow-up (years 15-26), effects due to antecedent illness were not apparent and a significant positive, linear relation between BMI and all-cause mortality was consistently found among middle-aged (30-54 y) and older (55-74 y) men. Disease-specific analyses of the later follow-up (years 15-26) revealed that the positive linear trends with all-cause mortality, were primarily due to excess risk of cardiovascular disease and cancer among the heavier men. Among older men, a significant inverse relation between BMI and respiratory disease mortality risk was identified during later follow-up (years 15-26), but this effect attenuated after restriction of the analyses to men with no baseline history of respiratory disease.
Conclusions: The re-analysis confirms the findings of a positive, linear relation between BMI and all-cause mortality, reported in the original study.