Is the Singh Index useful for evaluating osteoporosis?

摘要

The Singh Index was proposed by Singh and Nagath in 1970 to evaluate the degree of osteoporosis. The aim of this study was to appreciate the value SI in current practice. Method. We performed an analysis on 129 antero-posterior plain radiographies of proximal femurs without fractures or arthrosis, obtained during a period of three years. Four observers (orthopedists) analyzed these radiographies and classified each image into one of the six Singh categories. After a period of three months, the radiographies were reexamined by the same observers. In order to evaluate the value of the Singh Index, variability inter- and intra-observers was measured. These parameters evaluate the proportion of identical readings for the same set of radiographies for 2 different observers (interobservability) and the proportion of identical readings for the same observer at two different readings (intraobservability). The results were evaluated with the aid of statistic interpretation (kappa value). In the second stage of the evaluation, the relevance of the Singh index was assessed using dual energy X-ray absorptiometry (DXA). Results. For assessing interobservability, the four observers were grouped in pairs, resulting six possible pairs. Kappa was measured for each pair, and the final result represented an average of the kappa value. For interobservability, kappa value was 0.15. In order to determine intraobservability, we took into account the number of identical readings for the same observer at two different moments. The procedure for calculating kappa was similar. Mean kappa value for intraobservability was 0.19. According to the scale proposed by Landis and Koch, these figures suggest slight agreement (0.00 - 0.20). When comparing the results obtained by DXA with those by the Singh index, a significant discrepancy was also noticed. Conclusions. Based on these findings, we believe that the Singh Index, as proposed by the author, has a reduced significance and utility.