Association of age, sex, nutritional risk, serum 25-hydroxyvitamin D, serum uric acid, and exercise capacity with bone mineral density in elderly and very elderly inpatients: a cross-sectional study.

Objective: Risk factors for osteoporosis may vary according to different populations. Much remains unknown in elderly, especially very elder patients. We aim to investigate the association of age, sex, nutritional risk, serum 25-hydroxyvitamin D, serum uric acid, and physical function with bone mineral density in elderly and very elderly patients. Methods: Elderly hospitalized patients at the First Rehabilitation Hospital of Shanghai, China, from December 2019 to December 2020 who were older than 60 years old were selected. Combined with an activities of daily living (ADL) scale and nutritional assessment, the causes of BMD reductions in elderly and elderly patients were analysed. Results: A total of 94 patients (aged 63-98 years at baseline, with an average age of 83.56 ± 8.37 years) were enrolled. With increasing age, the BMD of the lumbar spine, femoral neck, and femoral shaft of elderly patients significantly decreased, and the incidence of osteoporosis (OP) significantly increased. The BMD of the lumbar spine was negatively correlated with female sex and positively correlated with serum 25-hydroxyvitamin D levels, the difference between actual body weight and ideal body weight, and blood uric acid levels; the BMD of the femoral neck was negatively correlated with age and female sex and positively correlated with height and geriatric nutrition risk index (GNRI) score; the BMD of the femoral shaft was negatively correlated with female sex and positively correlated with exercise capacity (ADL score). Conclusion: With increasing age, the BMD of the lumbar spine and the femoral shaft significantly decreased, and the incidence of OP significantly increased in elderly and very elderly patients. Aric acid may protect bone health in elder patients. Early attention to the nutritional status, exercise capacity, 25-hydroxyvitamin D level, and blood uric acid level in the elderly population can help identify high-risk elderly patients with OP.