Body Shape and Healthy Lifestyle Are Independent Predictors of Survival in Older Adults: NHANES 1999 to 2018

Peter D. Hart^{1, 2,}

¹Health Promotion Research, Havre, Montana, USA

²Kinesmetrics Lab, Tallahassee, Florida, USA

Cite this paper:
Peter D. Hart. Body Shape and Healthy Lifestyle Are Independent Predictors of Survival in Older Adults: NHANES 1999 to 2018. American Journal of Medical Sciences and Medicine. 2025; 13(4):53-59. doi: 10.12691/ajmsm-13-4-1

Abstract

Background: Various body measures have been found predictive of morbidity and mortality in population-based studies. Similarly, links between a healthy lifestyle and health outcomes are well established. However, the extent to which body shape and healthy lifestyle can independently predict death in elderly populations is less clear. Purpose: The aim of this study was to determine if measures of body shape and healthy lifestyle can independently predict all-cause mortality in older adults. Methods: A baseline sample of 9,610 adults 65+ years of age were included from ten cycles (1999-2018) of NHANES. A body shape index (BSI) was computed using objectively assessed anthropometric measures. A healthy lifestyle index (HLI, 0-to-8) was constructed using four rating scale measures that included physical activity (0-to-2), alcohol consumption (0-to-2), smoking (0-to-2), and BMI groups (0-to-2). To account for confounding health status, chronic conditions and activities of daily living (ADL) were considered. Survival analysis was employed to examine the independent associations between the predictors and risk of all-cause mortality. Linear regression was used to characterize the mortality risk trend across HLI scores by different BSI quartile groups. Results: A total of 4,059 all-cause deaths were observed during a mean (median) follow-up of 10.9 (10.8) years. BSI was an independent predictor of mortality with risk decreasing linearly (p<0.0001) from 4th (reference), 3rd (HR=0.85, 0.75-0.95), 2nd (HR=0.77, 0.67-0.88), and 1st (HR=0.72, 0.63-0.82) BSI quartiles. Similarly, HLI was an independent predictor with risk increasing linearly (p<0.0077) from HLI 7+ (reference), HLI 6 (HR=1.25, 1.01-1.56), HLI 5 (HR=1.27, 1.03-1.57), HLI 4 (HR=1.45, 1.18-1.78), HLI 3 (HR=1.52, 1.22-1.88), HLI 2 (HR=1.85, 1.48-2.30), HLI 1 (HR=2.00, 1.50-2.68), and HLI 0 (HR=2.03, 1.05-3.93). Additionally, predicted hazard means decreased linearly across HLI scores for each BSI quartile group with lower means observed in lower BSI quartile groups. However, a significant quadratic trend was seen in the 1st and 4th BSI quartile groups, indicating a rapid decline in mortality risk beginning at approximately HLI 4 for those BSI groups. Conclusion: These findings indicate that body shape and healthy lifestyle each influence mortality risk in older adults. Adopting healthy behaviors and improving abdominal fat metrics should be promoted among adult populations regardless of disease, functioning, and age.

Keywords:
Gerontology Healthy lifestyle Body shape index Mortality Population health

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