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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #344376
Research Project: Rural Aging Study

Location: Jean Mayer Human Nutrition Research Center On Aging

Title: Body mass index and all-cause mortality among older adults

Author
item CHENG, F - Pennsylvania State University
item GAO, X - Pennsylvania State University
item MITCHELL, D - Pennsylvania State University
item WOOD, C - Geisinger Medical Center
item STILL, C - Geisinger Medical Center
item ROLSTON, D - Geisinger Medical Center
item JENSEN, G - University Of Vermont College Of Medicine

Submitted to: Obesity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2016
Publication Date: 8/29/2016
Citation: Cheng, F.W., Gao, X., Mitchell, D.C., Wood, C., Still, C.D., Rolston, D., Jensen, G.L. 2016. Body mass index and all-cause mortality among older adults. Obesity. 24(10):2232-2239.

Interpretive Summary: Previous studies that have found that overweight/obesity is less of a risk factor for mortality in the elderly; however methodological issues with these studies have created some controversy. Therefore, a different methodological approach is warranted. Using different methodology which treats body mass index as a continuous variable, we found a lower risk among those with overweight and mild obesity and greater risk among persons with underweight, compared with those with body mass index in a normal range. These findings remained similar while controlling for additional variables including smoking and weight loss due to serious illness. Using a different approach than previously described, these results suggest that smoking and weight loss due to serious illness do not fully explain why overweight and mild obesity have a lower risk of all-cause mortality among older persons.

Technical Abstract: Objective: To examine the association between baseline body mass index (BMI, kg/m2) and all-cause mortality in a well-characterized cohort of older persons. Methods: The association between BMI (both as a categorical and continuous variable) and all-cause mortality was investigated using 4,565 Geisinger Rural Aging Study participants with baseline age 74.064.7 years (mean6SD) and BMI 29.565.3 kg/m2 over a mean of 10.963.8 years of follow-up. Results: The relationship between BMI (as a continuous variable) and all-cause mortality was found to be U-shaped (P nonlinearity <0.001). Controlling for age, sex, smoking, alcohol, laboratory values, medications, and comorbidity status, underweight (BMI <18.5 kg/m2) individuals had significantly greater adjusted risk of all-cause mortality than persons of BMI 18.5 to 24.9 kg/m2 (reference range). Participants with overweight (BMI 25.0–29.9 kg/m2) and class I obesity (BMI 30.0–34.9 kg/m2) had significantly lower adjusted-risk of all-cause mortality. Those with classes II/III obesity (BMI_35.0 kg/m2) did not have significantly greater adjusted-risk of all-cause mortality. Findings were consistent using propensity score weights and among never-smokers with 2- and 5-year lag analysis and among those with no identified chronic disease. Conclusions: A U-shaped association was observed between BMI and all-cause mortality with lower risk among older persons with overweight and class I obesity in comparison with those with BMI 18.5 to 24.9 kg/m2.