The association between body mass index, waist circumference and waist-to-hip-ratio with all-cause mortality in older adults: A systematic review

Abstract

Background & aims: The association between anthropometric obesity parameters and all-cause mortality in older adults is of significant interest due to the implications for public health and clinical practice. This systematic review aims to assess and synthesize the literature on the relationship between anthropometric obesity parameters, such as the body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), with all-cause mortality in older adults.

Methods: This systematic review was registered on the International Prospective Register of Systematic Reviews (PROSPERO - CRD42024521886). A systematic search was conducted across five databases: PubMed, EMBASE, Web of Science, SCOPUS, and LILACS. The study included: (1) older adults (≥60 years); (2) an observational-longitudinal study design (prospective and retrospective cohorts); (3) different anthropometric methods for the diagnosis of obesity; and (4) all-cause mortality as an outcome. The National Institutes of Health quality assessment tool for observational cohort and cross-sectional studies was employed to assess the methodological quality of the included studies.

Results: A total of 38 studies were included. Most studies have investigated associations between BMI and all-cause mortality. Among them, 9 studies found no significant association, 25 reported a protective effect, 1 identified BMI as a risk factor, and 4 observed a U-shaped relationship. Regarding WC, the results were conflicting: 15 studies found no association with mortality, 8 identified WC as a risk factor, and 6 suggested a protective effect. As for WHR, although it was the least frequently assessed measure, 8 studies identified it as a risk factor for mortality in older adults, 4 found no significant association, and 1 reported an inverse relationship. These findings highlight discrepancies in the associations between obesity measures and mortality.

Conclusion: BMI appears to be inversely associated with mortality in older adults, while findings for WC remain controversial. WHR demonstrates a positive association with mortality, but further research is needed to confirm these findings. Clinicians should ensure that older patients do not remain at lower BMI thresholds, as higher BMI values appear protective, particularly in the presence of diseases. This recommendation should be made on an individualized basis, considering the individual's health status. Recommendations at the individual level should also consider functional status and body composition measurements. Moreover, WHR may provide additional insights into mortality risk beyond BMI, highlighting its importance for clinical practice. These findings support an integrative approach to monitoring both metrics to better inform preventative strategies and resource allocation for aging populations. Cut-off points for anthropometric measures of obesity should be reassessed and standardized for older adults.

Keywords: All-cause mortality; Anthropometric parameters; Obesity; Older adults.