Discordance between hip and spine bone mineral density measurement using DXA: prevalence and risk factors.
BACKGROUND
Diagnostic discordance for osteoporosis is the presence of different categories of T-scores in 2 skeletal sites of an individual patient, falling into 2 different diagnostic categories identified by the World Health Organization classification system.


OBJECTIVE
To evaluate the prevalence and risk factors for T-score discordance between spine and total hip measurement sites.


METHODS
Demographic data, anthropometric measurements, and risk factors for osteoporosis were derived from a database of 3479 patients referred to a community-based outpatient osteoporosis testing center. Dual-energy x-ray absorptiometry (DXA) was performed on L1-L4 lumbar spine and total hips for all cases. Minor discordance was defined as present when the difference between 2 sites was no more than 1 World Health Organization diagnostic class. Major discordance was present when 1 site is osteoporotic and the other is normal. Subjects with incomplete data were excluded.


RESULTS
In 3479 participants (2871 women; mean age, 55.7 +/- 11.9 years), concordance of T-scores, minor discordance, and major discordance were seen in 54, 42, and 4%, respectively. In multivariate logistic regression analysis, age, menopause, and obesity were identified as risk factors against T-score discordance.


CONCLUSIONS
Densitometrists and clinicians should expect that at least 4 of every 10 patients tested by DXA to demonstrate T-score discordance between spine and total hip measurement sites. T-score discordance can occur for a variety of reasons related to physiologic and pathologic patient factors as well as the performance or analysis of DXA itself.
Mounach
A
A
Rheumatology and Physical Rehabilitation Department, Military Hospital Mohammed V, Rabat, Morocco.
Abayi
D A Mouinga
DA
Ghazi
M
M
Ghozlani
I
I
Nouijai
A
A
Achemlal
L
L
Bezza
A
A
El Maghraoui
A
A
D015502:Absorptiometry, Photon / Q000379:methods*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology*; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D016015:Logistic Models; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D008593:Menopause; D008875:Middle Aged; D015999:Multivariate Analysis; D010024:Osteoporosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D015203:Reproducibility of Results; D012307:Risk Factors; D055815:Young Adult