DEXA T-score Concordance and Discordance Between hip and Lumbar Spine

Choi, Jang Suk; An, Ki Chan; Lee, Chang Seop; Choi, Jong Moon; Kim, Joo Yong; Shin, Dong Reol

Abstract

OBJECTIVE
To evaluate the concordance, or discordance, of the osteoporotic diagnosis between femur neck and lumbar spine, using DEXA T-scores and the WHO classification.
MATERIALS AND METHODS
The BMD (Define?) on both hips and of the lumbar spine of 718 Korean females were measured. The mean age of the subjects was 55.5 years (31-91). The BMD data were obtained from 3 hip regions and from the lumbar spine, anteroposteriorly, using dual-energy x-ray absorptiometry (Lunar). The BMDs of femur neck and the L2-4 vertebrae were classified into normal (a T-score >-1), osteopenia (-1 < or = T-score < -2.5) and osteoporosis (-2.5< or =T-score) using the WHO definitions.
RESULTS
There was significant correlation between the femur neck and lumbar BMDs (r=0.772). However, the discordance rate was 33% for all the cases, but this was 20% in the subjects below 50 of age, 31% in the subjects in their 50's, 47% in their 60's and 42% when 70 or above. The discordance rates of the normal, osteopenic and osteoporotic groups were 21, 54 and 17% respectively, with the highest discordance rate in the osteopenia group. Among the 649 persons in the normal or osteopenia groups, in relation to the femur neck BMD, there were 67 (10.3%) in the osteoporotic group with L2-4 BMD. But the reverse situation was only 12 persons from 594 (2.0%). (Eds note: this whole section makes little sense? What were the BMDs? The last sentence is completely meaningless.)
CONCLUSIONS
The discordance rate between the femur neck and lumbar spine was as high as 33%, and was the highest in the osteopenia persons in their 60's. Therefore, in these persons the BMD of both sites should be checked together, but if not, the lumbar BMD should be checked first.