Obesity Increases Early Hip Fracture Risk in Postmenopausal Women

Data from an analysis of more than 12,000 postmenopausal women adds new evidence to the idea obesity can have a negative impact on bone health.

Results of the analysis, which was conducted by a team from Finland and the UK, indicate obesity was associated with earlier hip fracture, higher post-fracture mortality, and greater rates of BMD loss in a cohort with 25 years of follow-up data.

“Obesity associated with both early hip fracture risk and higher all-cause mortality. The impact of BMI on hip fracture risk in the aging population is a complex and multifactorial topic. Numerous overlapping risk factors and competing events such as comorbidities, poor health behavior, low functional capacity, and excessive all-cause mortality commonly coexist with obesity,” wrote investigators.

Despite established links to increased risk for a multitude of comorbid conditions, debate still exists over the impact of increased BMI on bone health. With this in mind, investigators sought to assess the long-term effects of increased BMI on hip fracture incidence in a cohort of postmenopausal women. Using the data from the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) study cohort, investigators identified 12,715 women for inclusion in their analysis.

Of note, OSTPRE includes more than 14,200 women born from 1932-1941 in a province in Finland. Beginning in 1989, these women received periodic questionnaires aimed at collecting information related to demographic and clinical characteristics of respondents. Based on these questionnaires, investigators established a pair of age classifications for the follow-up analysis—early (58-70 years) and late (more than 70 years).

Responders to the baseline questionnaire in 1989 were asked about their willingness to undergo bone densitometry and clinical measurement protocols. From this, investigators identified a subgroup of 3163 patients with data related to femoral neck bone mineral density (BMD).

The mean follow-up time for the current study cohort was 18.3 years. At baseline, the mean BMI was 26.7 kg/m2. Of the 12,715 women included, 39.6% met criteria for having normal body weight, 40% were considered overweight, 19.9% were considered obese, and 0.5% were considered underweight. A total of 427 occurred during the 233,096 person-years of follow-up.

Upon analysis, results indicated patients in both the obese (HR, 2.3; 95% CI, 1.4-3.7) and normal-weight (HR, 2.0; 95% CI, 1.3-3.1) groups had a higher risk of early hip fracture compared with the overweight group. This effect was not seen when assessing late hip fracture risk between the 3 BMI categories.

Further analysis indicated women considered obese were at a greater risk of mortality (HR, 1.6; 95% CI, 1.4-1.8) and had a greater baseline BMD than their counterparts in the normal weight group. Additionally, women considered obese appeared to have greater bone loss during the study period when compared against other groups of women (P <.001).

“Obesity associates with earlier hip fracture and higher post-fracture mortality. The obese women with low BMD have clearly the highest risk of hip fracture. This combination increases hip fracture risk more than either of the factors alone,” wrote investigators.

This study, “Obesity is associated with early hip fracture risk in postmenopausal women: a 25-year follow-up,” was published in Osteoporosis International.