Associations between body composition and the risk of fracture according to bone mineral density in postmenopausal women: a population-based database cohort study

Objective: We aimed to investigate the associations of body composition and the risk of fracture in postmenopausal women, stratified based on bone mineral density. Methods: A population-based cohort study using the database of the National Screening Program for Transitional Ages with women aged 66 years was performed. Bone mineral density was categorized as normal, osteopenia, and osteoporosis. The following body mass index (BMI) categories for general obesity were used: underweight (<18.5), normal (18.5-22.9), overweight (23-24.9), obese (25-29.9), and severely obese (≥30 kg/m²). Waist circumference (WC) used for central obesity assessment was categorized into 5 groups. Newly diagnosed fracture during the follow-up period defined based on ICD-10 codes was the primary outcome. Results: During 7.7 ± 1.4 years of follow-up, 41 672 (17.9%) participants experienced any fracture, 20 326 (8.7%) experienced vertebral fractures (VFs), and 2883 (1.2%) experienced hip fractures (HFs). The adjusted hazard ratios (aHRs) for any fracture showed a progressive increase with higher BMI and WC categories in individual with osteopenia and osteoporosis. Regarding VF, aHR was highest in severely obese individuals with osteoporosis (aHR [95% CI], 3.45 [2.99-3.97]) and in individuals with WC ≥ 95cm with osteoporosis (4.79 [4.09-5.60]). The aHR [95% CI] for HF was highest in the underweight group with osteopenia (1.94 [1.16-3.27]) and osteoporosis (2.96 [2.15-4.10]). In central obesity individuals with WC ≥ 95cm, aHR [95% CI] for HF was 2.80 [1.91-4.91]. Conclusions: General obesity and central obesity are not protective against any fracture, VF and HF in postmenopausal women with osteopenia or osteoporosis.