Background Diagnostic discordance for osteoporosis is the presence of different T-scores in two skeletal sites in the same subject leading to different WHO diagnostic categories. Discordance is defined as minor when the difference between two sites is no more than one WHO diagnostic class and major when one site is osteoporotic and the other is normal.
Objectives To determine the percentage of minor and major diagnostic discordance and identify associated factors in patients from the United Arab Emirates (UAE) diagnosed with osteoporosis.
Methods All patients born in North Africa-Middle East region (as per WHO classification) ≥50 years old seen in rheumatology clinics of our tertiary level hospital from 2011 to 2013, diagnosed with osteoporosis were identified through an internal audit. Details of the first Dual-X-Ray-Absorptiometry test (DXA) during the study period were extracted, including weight, height, T score at femoral neck and total hip in the right side (RFN, RTH) and left side (LFN,LTH) and T score at lumbar spine (LS). Differences in T scores and degree of discordance between sites were calculated. Age, weight, height and BMI were analysed as contributing factors.
Results One hundred and seventy-one patients with osteoporosis and DXA test were identified. The mean age was 64.4 (±9.4 SD) and 142 (83%) were females. Diagnostic agreement among all skeletal sites was found in only 16% of patients. Of the cohort, 42% showed one major discordance and 65% showed minor discordance. Maximum concordance was found between RTH and LTH (80%) and minimum between LS and LTH (26%). Minor discordance was present in about half of the patients when comparing spine to any hip site, and in around one quarter when comparing ipsilateral TH and FN sites. Major discordance in LS compared to hip locations was present almost in one third of the patients. Of the four possible spine-hip comparisons, between 89 and 91% of the discordant cases exhibited LS scores lower than the respective hip site. No significant correlation with age, weight, height or BMI was found for the degree of discordance.
Conclusions Major and minor spine-hip diagnostic discordance is higher in patients from UAE diagnosed with osteoporosis compared to that reported elsewhere1,2. Inter-hip discordance is compatible with previous data3. Multiple-site measurements seem mandatory not to miss patients at high risk for osteoporosis.
Gnudi S et al, J Clin Densitom 2000
Mounach A et al, Seminars Arthritis Rheum 2009
Hamdy R et al, Osteoporos Int 2006
Disclosure of Interest None declared