Validation of the Simple Calculated Osteoporosis Risk Estimation (SCORE) for Patient Selection for Bone Densitometry

Abstract:

Bone densitometry using dual energy X-ray absorptiometry (DXA) is the ‘gold standard’ for osteoporosis diagnosis. However, mass screening for osteoporosis has not been recommended, and no consensus has been reached regarding specific targeted screening programs. Recently, the Simple Calculated Osteoporosis Risk Estimation (SCORE) was developed to identify postmenopausal women likely to have low BMD (≤−2.0 SD of the young adult normal), who may be selected for DXA testing. This instrument uses a case-selective approach to screen for osteoporosis by summing a score based on: age, race, rheumatoid arthritis, history of nontraumatic fracture over 45 years of age, estrogen use, and weight. In our study, SCORE was validated using 398 postmenopausal women at least 45 years of age residing within 50 km of Toronto, Ontario, Canada (one of 9 centers of the Canadian Multicentre Osteoporosis Study, a national population-based study). At the recommended threshold of 6, SCORE had a sensitivity of 90%, specificity of 32% and a positive predictive value of 64%. From receiver operating characteristic (ROC) analysis, no threshold identified SCORE as a useful instrument in our population; area under the ROC curve was 0.71. Specificity of the SCORE is poor; at the recommended threshold of 6, 68% of those with normal bone mineral density (BMD) would be selected for bone densitometry. Development and validation of SCORE by Lydick and colleagues may have been confounded by the nature of the study sample; sampling from specialty clinics; and by the choice of outcome, combining data from different DXA machines, and using only data from the femoral neck to identify low BMD. A simple and effective approach to select patients for bone densitometry has yet to be established.