Risk of Osteoporotic Fractures Among Obese Women Based on Body Mass Index and Waist Circumference: A Nationwide Cohort in South Korea

Trunk-to-leg-volume ratio is not associated with bone density or fracture risk in middle-aged adults: results from the National Health and Nutrition Examination Survey

Unlike a high body mass index or waist circumference, a high trunk-to-leg-volume ratio does not associate with a lower risk of osteopenia/osteoporosis at the femoral neck. While elevated TLVR showed a suggestive association with a history of wrist fracture in women, additional research is needed to confirm this suggestion.

PURPOSE

Body mass index (BMI) and waist circumference (WC) are commonly used to predict bone health, which is typically assessed via bone mineral density (BMD). Trunk-to-leg-volume ratio (TLVR), a relatively novel measure, predicts cardiometabolic outcomes, but its relationships with BMD and fracture remain unstudied. This study evaluated these anthropometric measures' associations with BMD and fracture in Americans aged 40-60 years.

METHODS

Analyses of middle-aged adults from the 2013-2014 to 2017-2018 National Health and Nutrition Examination Survey were conducted. Whole-body, dual-energy X-ray absorptiometry was used to quantify TLVR as well as BMD at the lumbar spine, while a femur-specific scan was used to quantify femoral neck BMD. Fracture history was self-reported. Linear and logistic regression models were constructed with age, diabetes, smoking, race/ethnicity, education, and physical activity as confounding variables.

RESULTS

TLVR was generally not associated with BMD, while WC and BMI showed positive associations with femoral neck BMD. Odds of osteopenia/osteoporosis at the femoral neck were ~ 65-80% lower among participants in the highest tertile of BMI and WC versus the lowest (p < 0.001). There were no statistically significant associations between anthropometric predictors and fracture. Women in tertiles 2 or 3 of TLVR (p = 0.097 and 0.079, respectively) did have 2.66 times the odds of wrist fracture than women in tertile 1, but this was not significant.

CONCLUSION

As shown in previous research, BMI and WC show positive associations with femoral BMD. In contrast, the more novel anthropometric marker TLVR shows no association with femoral BMD, and no clear association with fracture.

Added value of waist circumference to body mass index for predicting fracture risk in obesity: a prospective study from the CARTaGENE cohort

Larger waist circumference is significantly associated with an increased risk of distal lower limb fractures in individuals aged 40-70 years with a body mass index within the normal or overweight category. Therefore, waist circumference provides additive information to body mass index for the identification of individuals at risk of obesity-related fractures.

INTRODUCTION

Waist circumference (WC) is a stronger risk factor of metabolic disorders than body mass index (BMI), but whether it holds true for fracture risk prediction remains unclear. We aimed to evaluate relationships between WC and fracture incidence within BMI categories and evaluate whether BMI modifies these relationships.

METHODS

Men and women aged 40-70 years from the CARTaGENE cohort were divided by BMI category at baseline: normal weight, overweight, and obesity. Incident fractures were identified over 7 years via linkage with healthcare administrative databases. Cox proportional hazard models estimated the relationships between WC and incident fractures at any site and by skeletal site within each BMI category. Results are reported as adjusted hazard ratios (95% confidence intervals) per 10 cm increase in WC. Effect modification was evaluated qualitatively by comparing relationships between BMI categories.

RESULTS

Of the 18 236 individuals included, 754 sustained a fracture. Significant relationships were found between WC and distal lower limb fractures in the normal (1.25 [1.08, 1.45]) and overweight (1.28 [1.07, 1.52]) BMI categories, but not in the obesity category. In the overweight category, we found an increased risk of distal upper limb fractures with increasing WC (1.49 [1.04, 2.15]). No significant relationship was observed regarding WC and fracture risk at any site or major osteoporotic fractures. An effect modification of BMI on the relationships between WC and distal lower limb fractures was observed.

CONCLUSION

WC provides both independent and additive information to BMI for the identification of individuals at risk of obesity-related fractures.