Radiographic absorptiometry for pre-screening of osteoporosis in patients with low energy fractures

Dual energy X-ray absorptiometry (DEXA) is the most accurate method and thus the method of choice for diagnosing osteoporosis. Due to the limited access to DEXA-scanners, screening of patients with low energy fractures (LEF) for osteoporosis is not routinely performed in Denmark. Pre-screening with a simple, less expensive device might be able to exclude patients with normal bone mineral density (BMD) from further DEXA-scans. We aimed to determine the frequency of osteoporosis in patients with LEF, and evaluate the diagnostic impact of a radiographic absorptiometry (RA) scanner in the casualty department of a major Danish county hospital. In a 5-month period, 136 adult patients with LEF were invited for BMD measurements. In 74 (54%) patients DEXA-scans (spine and femoral neck) and phalangeal RA-scans were performed. A total of 86% of the patients were female and 39% were suffering from osteoporosis (T-scores ≤ -2.5) according to the DEXA results. RA-BMD and T-scores differed significantly between the two groups, with and without osteoporosis (p < 0.001). Comparing T-scores from RA with the lowest T-scores from DEXA, a highly significant correlation was found for women (R=0.7, p < 0.001). Using a RA cut-off value (T-score < -1) for women ensuring 100% sensitivity for identifying women with osteoporosis, the positive predictive value was 46%. Up to 19% of DEXA-scans could be avoided in this setting. In our population the simple RA-BMD-method was cost-effective as a pre-screening tool for osteoporosis in women. However, the final diagnosis still relies on results from DEXA-scans.