Spine deformity index in osteoporotic women: relations to forearm and vertebral bone mineral measurements and to iliac crest ash density

Bone densitometric measurements are widely used for monitoring therapeutic regimens for osteoporosis. However, it is a matter of debate which measurement site is most appropriate for prediction of individual fracture risk. The aim of this cross-sectional study was to investigate the relationship between bone mineral measurements at various sites and spine deformity index (SDI) in osteoporotic women. The SDI was determined in 37 osteoporotic women aged 56-87 years (mean 70.9 years). Peripheral (single-photon absorptiometry of the distal forearm, and iliac crest ash content) and axial (dual-photon absorptiometry of the lumbar spine) bone mass measurements were obtained. SDI increased with age (r = 0.34, p < 0.05), whereas forearm BMC (r = -0.52, p < 0.002) and forearm BMD (r = -0.62, p < 0.0001) decreased. No significant age-related changes were observed in lumbar BMC or iliac crest ash content in these osteoporotic women. A highly significant correlation was found between SDI and lumbar BMC (r = -0.60, p < 0.01). A significant, but less pronounced correlation was found between SDI and forearm BMC (r = -0.37, p < 0.05), whereas no relation was revealed between SDI and forearm BMD or iliac crest ash content. In a multiple regression model, the relationship between lumbar BMC and SDI remained significant after adjusting for the influence of age, whereas the relationship to forearm BMC disappeared. Furthermore, a multiple regression analysis was performed in order to evaluate the ability of all four bone mass measurements and age to predict variations in SDI.(ABSTRACT TRUNCATED AT 250 WORDS)