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 therape utic regimens for osteoporosis. However, it is a matter of debate whic h measurement site is most appropriate for prediction of individual fr acture risk. The aim of this cross-sectional study was to investigate the relationship between bone mineral measurements at various sites an d spine deformity index (SDI) in osteoporotic women. The SDI was deter mined in 37 osteoporotic women aged 56-87 years (mean 70.9 years). Per ipheral (single-photon absorptiometry of the distal forearm, and iliac crest ash content) and axial (dual-photon absorptiometry of the lumba r 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 B MD (r=-0.62, p<0.0001) decreased. No significant age-related changes w ere observed in lumbar BMC or iliac crest ash content in these osteopo rotic women. A highly significant correlation was found between SDI an d lumbar BMC (r= -0.60, p<0.01). A significant, but less pronounced co rrelation was found between SDI and forearm BMC (r= -0.37, p<0.05), wh ereas no relation was revealed between SDI and forearm BMD or iliac cr est ash content. In a multiple regression model, the relationship betw een lumbar BMC and SDI remained significant after adjusting for the in fluence of age, whereas the relationship to forearm BMC disappeared. F urthermore, a multiple regression analysis was performed in order to e valuate the ability of all four bone mass measurements and age to pred ict variations in SDI. Lumbar BMC was the single significant predictor of SDI in this model (r=-0.68, p<0.01). This study indicates that the risk of vertebral fracture is best estimated by bone mass determined in the spine.