Past body mass index and risk of mortality among women.
BACKGROUND
Epidemiologic studies of body mass index (BMI) in relation to mortality commonly exclude persons with health conditions and/or a history of smoking to prevent bias resulting from illness-related weight loss ('reverse causation'). Analysis of BMI from an earlier time period may minimize reverse causation without requiring exclusion of participants based on disease or smoking history.


METHODS
We prospectively examined BMI based on technician measurements of weight and height from 10 years prior to start of follow-up in relation to subsequent mortality in a cohort of 50 186 women who were 40-93 years old at baseline in 1987-1989. Deaths were ascertained through the US National Death Index. Proportional hazards regression was used to estimate hazard ratios (HRs) of mortality, adjusted for age, education, race/ethnicity, income, menopausal hormone use, smoking and physical activity.


RESULTS
During 10 years of follow-up through 1997, 5201 women died. Overall, we observed a J-shaped association between BMI and mortality, with increased risk for women who were underweight, overweight or obese. The HRs and 95% confidence intervals of mortality for BMI categories of <18.5, 18.5-20.9, 21.0-23.4 (reference), 23.5-24.9, 25.0-27.4, 27.5-29.9, 30.0-34.9 and 35.0+ kg m(-2) were 1.43 (1.19, 1.72), 1.07 (0.98, 1.17), 1.00 (reference), 1.10 (1.00, 1.20), 1.20 (1.11, 1.31), 1.23 (1.11, 1.37), 1.60 (1.44, 1.77) and 1.92 (1.64, 2.24). There was little evidence that pre-existing conditions (heart disease, diabetes and/or cancer) or smoking history modified the past BMI and mortality relation (P=0.54 and 0.76).


CONCLUSIONS
In this large cohort of women, BMI based on technician measurements of weight and height from 10 years prior to baseline showed increased risk for mortality across the range of overweight and obesity, regardless of disease and smoking history. Observed associations between overweight, obesity and mortality in healthy individuals may also apply to persons with a history of disease or smoking.
Moore
S C
SC
Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Department of Health and Human Services, Bethesda, MD 20892, USA. moorest@mail.nih.gov
Mayne
S T
ST
Graubard
B I
BI
Schatzkin
A
A
Albanes
D
D
Schairer
C
C
Hoover
R N
RN
Leitzmann
M F
MF
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D002423:Cause of Death / Q000639:trends; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008017:Life Expectancy / Q000639:trends*; D008875:Middle Aged; D009765:Obesity / Q000401:mortality*; D011446:Prospective Studies; D012307:Risk Factors; D013851:Thinness / Q000401:mortality*