Added value of bone mineral density in hip fracture risk scores

Hip fractures constitute a major health problem. For effective prevention, high-risk groups need to be identified. The objective here was to develop hip fracture risk scores while assessing the added value of bone mineral density relative to more conventional risk indicators. We prospectively followed during 4 years a cohort of 5208 persons (2193 men) aged 55 years and over from the Rotterdam Study, a population-based cohort study conducted in the Netherlands. Risk scores for hip fracture were constructed using several conventional risk indicators requiring interview and anthropometry only, and bone mineral density. During follow-up, 50 persons (14 men) suffered hip fracture. Hip fracture risk was independently determined by age, gender, height, the use of a walking aid, cigarette smoking, and either bone mineral density or weight. We developed two risk scores, with and without bone mineral density. The observed 4-year risk ranged from 3/3389 (0.1%) to 17/169 (10.1%) for the lowest and highest category of the score including bone mineral density, respectively. For the score without bone mineral density, these risks were 8/3117 (0.3%) and 16/144 (11.1%), respectively. The area under the receiver operating characteristic curve indicating discriminatory power was 0.88 for the risk score including, and 0.83 for the score excluding, bone mineral density (p for difference = 0.04). In conclusion, risk scores with and without bone mineral density measurement can be used for hip fracture risk assessment in elderly persons. While the score with bone mineral density has a modestly better performance, the score requiring interview and anthropometry only may be especially useful in primary care settings.