T-plus Z-score in the assessment of relative fracture risk

THE OBJECTIVE OF THE STUDY: We aimed to prove that the relative risk of fractures (RR) is higher in women whose T- and Z-score values come under the category of increased risk than in the women whose T-score only falls within the category of increased risk.

We analysed 498 (n=498) densitometric findings from the area of proximal femur: neck (ROI1), Ward's area (ROI2), great trochanter (ROI3) (DXA-dual energy X-ray absorptiometry, Osteocore II, France) from a population of Bratislava women of an average age of 59.71 years <58.63; 60.80>. Measured values of T- and Z-score were categorized as follows: 1--increased fracture risk (T-score<-2.5 SD/T=1, Z-score-2.5 SD/T=0, Z-score>-1.0 SD/Z=0).

RR for development of fracture was higher for all measurement sites (ROI(1)-29.87; ROI(2)-15.3; ROI(3)-5.5) for women having T-score<-2.5 SD and simultaneously Z-score-1.0 SD. When the women were divided according to age into two groups, it was found that the RR of fracture for women<65 years having a T-score<-2.5 SD and also a Z-scoreor=65 years) had a RR for ROI(1)-32.61, for ROI(2)-7.72, and for ROI(3)-6.9. The probability (P) of the presence of women with T-score values<-2.5 SD and Z-scoreor=65 years was for ROI1 75%; ROI2 98% and for ROI3 100%.

The study's contribution lies in the finding that the relative fracture risk of the proximal femur in women increases if the T-score is <-2.5 SD and, simultaneously, the Z-score