Low bone mineral density and fracture burden in postmenopausal womenBackground: The study objectives were to determine fracture rates in relation to bone mineral density at various central skeletal sites, using the World Health Organization definition for osteoporosis (T-score -2.5 or less), and to contrast fracture patterns among women 50 to 64 years of age with those among women 65 years of age and older. Methods:Historical cohort study with a mean observation period of 3.2 (standard deviation [SD] 1.5) years. The study group (16 505 women 50 years of age or older) was drawn from the Manitoba Bone Density Program database, which includes all bone mineral density results for Manitoba. Baseline density measurements for the lumbar spine and hip were performed with dual-energy x-ray absorptiometry. Outcomes included the percentage of osteoporotic fractures and the rates of fracture and excess fracture (per 1000 person-years) among postmenopausal women with osteopenia and osteoporosis relative to those with normal bone mineral density (according to the classification of the World Health Organization). Results:The mean age was 65 (SD 9) years, and the mean Tscores for all sites fell within the osteopenic category. There were 765 incident fractures (fracture rate 14.5 [95% confidence interval, CI, 13.5-15.6 [per 1000 person-years). Fracture rates were significantly higher among women 65 years of age or older than among women 50-64 years of age .7] per 1000 person-years, p < 0.001). Although fracture rates were significantly higher among women with osteoporotic T-scores, most fractures occurred in women with nonosteoporotic values (min-max: 59.7%-67.8%). Interpretation:In this study, most of the postmenopausal women with osteoporotic fractures had nonosteoporotic bone mineral density values. This finding highlights the importance of considering key clinical risk factors that operate independently of bone mineral density (such as age) when assessing fracture risk. Abstract

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.

Bone density measurements are effective for predicting fractures in clinical practice. However, hip measurements were superior to the spine in overall osteoporotic fracture prediction.

Background: Bone density measurement with dualenergy x-ray absorptiometry is widely used for fracture risk assessment. Discordance between measurement sites is common, but it is unclear how this affects fracture prediction. Methods: We performed a historical cohort study among 16 505 women 50 years or older at the time of baseline dual-energy x-ray absorptiometry of the spine and hip (mean ± SD observation period, 3.2 ± 1.5 years). The study population was drawn from a database that contains all clinical dual-energy x-ray absorptiometry test results for the province of Manitoba, Canada. Each subject's longitudinal health service record was assessed for the presence of fracture codes after bone density testing. The likelihood ratio test was used to assess the improvement in fracture prediction from Cox proportional hazards models using bone density covariates from a single site or from combined sites. Results: Age-adjusted hazard ratios (HRs) per standard deviation for osteoporotic fracture ranged from 1.61 (95% confidence interval [CI], 1.39-1.87) for the lumbar spine to 1.85 (95% CI, 1.70-2.01) for the total hip, with intermediate values for the femur neck (HR, 1.76 [95% CI, 1.62-1.92]) and trochanter (HR, 1.77 [95% CI, 1.63-1.92]). For fracture prediction, use of the minimum bone density measurement was no better than use of a hip measurement alone. When the total hip measurement was included in a fracture prediction model for the overall population, none of the other measurements added substantial information. The spine was the most useful site for the prediction of spine fractures alone. Conclusions: Proximal femur bone density measurements consistently outperformed lumbar spine measurements for global fracture prediction. In this cohort, the total hip was the best site for overall fracture assessment.

Background: Wrist fractures are the most prevalent type of fracture occurring in postmenopausal women. We sought to contrast the probability of recurrent osteoporotic fractures after a primary wrist fracture with other important primary fracture sites. Methods: A historical cohort study comprising 21 432 women 45 years or older referred for bone mineral density (BMD) testing. Longitudinal health service records were assessed for the presence of fracture codes before and after BMD testing (359 737 person-years of observation). Results: A total of 2652 women (12.4%) experienced a primary fracture (wrist, vertebra, humerus, hip) prior to BMD testing, of which wrist fractures were the largest single group (1225 [46.2%]). The adjusted hazard ratio (HR) for recurrent osteoporotic fracture following a primary wrist fracture (HR, 1.58; 95% confidence interval [CI], 1.29-1.93) was lower than for other primary fractures (HR, 2.66; 95% CI, 2.30-3.08). Primary wrist fractures were not significantly associated with subsequent hip fractures (adjusted HR, 1.29; 95% CI, 0.88-1.89), whereas other primary fracture sites were individually and collectively significant predictors of future hip fractures (HR, 1.72; 95% CI, 1.31-2.26). The 10-year probability of any recurrent fracture after a primary wrist fracture was 14.2% (95% CI, 11.9%-16.5%), which was significantly less than for other primary fractures (spine, 25.7%; hip, 24.9%; humerus, 23.7%; PϽ.001 for all comparisons vs wrist) but greater than in those without prior fractures (10.8%; P Ͻ .001). The relationship between BMD and fracture risk was much stronger after a primary wrist fracture (HR, 2.20 per standard deviation; 95% CI, 1.70-2.80) than after other primary osteoporotic fractures (HR, 1.21; 95% CI, 1.05-1.40), reflecting the dominance of the other fracture information over BMD. Conclusions: Wrist fractures are the most common of the clinical osteoporotic fractures in patients referred for BMD testing. However, the risk of recurrent fractures in the 10 years following a wrist fracture is substantially lower than that following other osteoporotic fractures, although it remains significantly higher than for those who have yet to experience a fracture.