Comparison of Singh index accuracy and dual energy X-ray absorptiometry bone mineral density measurement for evaluating osteoporosis

Background: The Singh index is an inexpensive simple method to evaluate bone density, commonly used to assess osteoporosis is based on the radiological appearance of the trabecular bone structure of the proximal femur on a plain antero-posterior (AP) radiograph. The purpose of this study was to compare between Singh index and bone mineral density measurement using dual energy X-ray absorptiometry (DXA). Materials and Methods: Three orthopedists evaluated radiographs of 72 patients suspected with osteoporosis. The inter-observer agreements of the Singh index were obtained by using kappa statistics. The bone mineral density (BMD) of proximal femur was measured by DXA in all patients, and then the BMD results were compared with those of Singh index by using reference radiographic charts of the Singh index method. Dual-energy X-ray absorptiometry was used to measure bone mineral density. A Norland XR46 system was used for the investigations. Results: The inter-observer agreement kappa values were 0.01, 0.07 and 0.09 (mean value: 0.05) and the strength of the observer agreements was negligible. The obtained osteoporosis prevalence among the studied patients was 38.9%. Conclusion: The inter-observer variation was large, there was no any correlation between the Singh index and bone densitometry. So, the index cannot be used for evaluating and osteoporosis diagnosis, because of its low reliability. Iran. J. Radiat. Res., 2010 8 (2): 123-128