Associations of body size with all-cause and cause-specific mortality in healthy older adults

Prudence R. Carr, Katherine L. Webb, Johannes T. Neumann, Le T.P. Thao, Lawrence J. Beilin, Michael E. Ernst, Bernadette Fitzgibbon, Danijela Gasevic, Mark R. Nelson, Anne B. Newman, Suzanne G. Orchard, Alice Owen, Christopher M. Reid, Nigel P. Stocks, Andrew M. Tonkin, Robyn L. Woods, John J. McNeil

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In the general population, body mass index (BMI) and waist circumference are recognized risk factors for several chronic diseases and all-cause mortality. However, whether these associations are the same for older adults is less clear. The association of baseline BMI and waist circumference with all-cause and cause-specific mortality was investigated in 18,209 Australian and US participants (mean age: 75.1 ± 4.5 years) from the ASPirin in Reducing Events in the Elderly (ASPREE) study, followed up for a median of 6.9 years (IQR: 5.7, 8.0). There were substantially different relationships observed in men and women. In men, the lowest risk of all-cause and cardiovascular mortality was observed with a BMI in the range 25.0–29.9 kg/m2 [HR25-29.9 vs 21–24.9 kg/m2: 0.85; 95% CI, 0.73–1.00] while the highest risk was in those who were underweight [HRBMI <21 kg/m2 vs BMI 21–24.9 kg/m2: 1.82; 95% CI 1.30–2.55], leading to a clear U-shaped relationship. In women, all-cause mortality was highest in those with the lowest BMI leading to a J-shaped relationship (HRBMI <21 kg/m2 vs BMI 21–24.9 kg/m2: 1.64; 95% CI 1.26–2.14). Waist circumference showed a weaker relationship with all-cause mortality in both men and women. There was little evidence of a relationship between either index of body size and subsequent cancer mortality in men or women, while non-cardiovascular non-cancer mortality was higher in underweight participants. For older men, being overweight was found to be associated with a lower risk of all-cause mortality, while among both men and women, a BMI in the underweight category was associated with a higher risk. Waist circumference alone had little association with all-cause or cause-specific mortality risk. Trial registration ASPREE number NCT01038583.

Original languageEnglish
Article number3799
Number of pages9
JournalScientific Reports
Issue number1
Publication statusPublished - Dec 2023

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