Weight and body mass index predict bone mineral density and fractures in women aged 40 to 59 years

Abstract

Weight and body mass index are associated with low bone mineral density and fractures in older women. This retrospective cohort study confirms a similar relationship in women aged 40 to 59 years.

Introduction: Risk factors for the prediction of osteoporosis and fractures have been less thoroughly studied in younger women. We evaluated the associations between weight, body mass index (BMI), the Osteoporosis Self-Assessment Tool (OST), bone mineral density (BMD) and fracture risk in women aged 40 to 59 years.

Methods: Using administrative health management databases, we conducted a retrospective cohort study in 8,254 women aged 40-59 years who had baseline BMD testing. Linear regression and Cox proportional multivariate models were created to examine the associations with weight, BMI, OST, BMD, and subsequent fractures throughout a 3.3-year follow-up.

Results: Body weight, BMI, and OST had a similar overall performance in their ability to classify women with femoral neck T-score < or = -2.5. Throughout 27,256 person years of observation, 225 women experienced one or more fractures. After adjustment for age, prevalent fractures, and use of corticosteroids, each standard deviation decrease in weight was associated with a 19% increase in the risk of incident fracture (95% CI: 1.01-1.35). Femoral neck BMD and the presence of prevalent fractures were also associated with the risk of incident fractures.

Conclusions: Low weight and BMI predict osteoporosis and are associated with increased fracture risk in younger women. The negative impact of low body weight on bone health should be more widely recognized.