Incidence and predictors of fractures in older adults with and without obesity defined by body mass index versus body fat percentage

Anoohya Gandham; Ayse Zengin; Maxine P Bonham; Tania Winzenberg; Saliu Balogun; Feitong Wu; Dawn Aitken; Flavia Cicuttini; Peter R Ebeling; Graeme Jones; David Scott

doi:10.1016/j.bone.2020.115546

Incidence and predictors of fractures in older adults with and without obesity defined by body mass index versus body fat percentage

Bone. 2020 Nov:140:115546. doi: 10.1016/j.bone.2020.115546. Epub 2020 Jul 27.

Authors

Affiliations

¹ Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia. Electronic address: anoohya.gandham@monash.edu.
² Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia.
³ Department of Nutrition, Dietetics and Food, Monash University, Notting Hill, Victoria, Australia.
⁴ Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
⁵ Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia.
⁶ Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia; Department of Medicine and Australian Institute of Musculoskeletal Science, Melbourne Medical School - Western Campus, The University of Melbourne, St Albans, Victoria, Australia; Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia; Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia.

PMID: 32730938
DOI: 10.1016/j.bone.2020.115546

Abstract

Purpose: The aim of this study was to determine and compare risk factors associated with incident fractures in older adults with and without obesity, defined by both body mass index (BMI) and body fat percentage.

Methods: 1,099 older adults (mean ± standard deviation age = 63.0 ± 7.5) years, participated in this prospective cohort study. Obesity status at baseline was defined by BMI (≥30 kg/m²) obtained by anthropometry and body fat percentage (≥30% for men and ≥40% for women) assessed by dual-energy X-ray absorptiometry (DXA). Total hip and lumbar spine areal bone mineral density (aBMD) were assessed by DXA up to five years. Incident fractures were self-reported up to 10 years.

Results: Prevalence of obesity was 28% according to BMI and 43% according to body fat percentage. Obese older adults by BMI, but not body fat percentage, had significantly higher aBMD at the total hip and spine compared with non-obese (both p-value<0.05). Obese older adults by body fat percentage had significantly higher likelihood of all incident fractures (OR: 1.71; CI:1.08, 2.71) and non-vertebral fractures (OR: 1.88; CI:1.16, 3.04) compared with non-obese after adjusting for confounders. Conversely, obese older adults by BMI had a significantly lower likelihood (OR: 0.54; CI:0.31, 0.94) of non-vertebral fractures although this was no longer significant after adjustment for total hip aBMD (all p-value > 0.05). Mediation analysis confirmed that aBMD meditated the effects of BMI, but not body fat percentage, on all incident fractures. Higher baseline falls risk score was the only consistent predictor of increased likelihood of incident fracture in obese individuals only, according to both BMI and body fat percentage (both p-value<0.05).

Conclusions: Obesity defined by body fat percentage is associated with increased likelihood of incident fractures in community-dwelling older adults, whereas those who are obese according to BMI have reduced likelihood of incident fracture which appears to be explained by higher aBMD. Falls risk assessment may improve identification of obese older adults at increased risk of incident fractures.

Keywords: Aging; Bone; Fracture; Obesity; Older adults.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Absorptiometry, Photon
Adipose Tissue
Aged
Body Mass Index
Bone Density*
Female
Humans
Incidence
Male
Middle Aged
Obesity* / complications
Obesity* / epidemiology
Prospective Studies