The reference value of trabecular bone score (TBS) in the Iranian population

Background Trabecular bone score (TBS), as a tool for measurement of bone microarchitecture, represents fracture risk independently of bone density. The aim of this study was to estimate the reference values of TBS in both genders among the Iranian population to evaluate osteoporotic fractures in the future. Methods The study was performed on healthy Iranian subjects who live in urban areas of Bushehr city, the capital of Bushehr province in southwestern Iran. The participants in this study were selected through a multistage, age and sex stratified, cluster random sampling. The TBS of L1-L4 was assessed by spine DXA images using TBS iNsight software (Discovery WI, Hologic Inc, USA). Age-related models of TBS were constructed using piecewise linear regression analysis. Results In total, 691 participants aged ≥ 18 years (381 men and 310 women) were selected for the study. The mean and standard deviation (SD) of TBS value for men was 1.420 ± 0.094 and the age at the peak TBS was 30.0 years. Among women, the corresponding value for the mean of TBS was 1.428 ± 0.070 and the age at the peak TBS was 24.5 years. Two SDs below the mean of TBS were 1.326 in men and 1.357 in women. Therefore, the following normal range for TBS values has been proposed: Among men, TBS ≥ 1.326 is considered to be normal; TBS between 1.231 and 1.326 is considered to be partially degraded microarchitecture; and TBS ≤ 1.231defined degraded microarchitecture. Among women, TBS categories are defined as normal ≥ 1.357, partially degraded between 1.287 and 1.357 and degraded ≤ 1.287. Conclusions This was the first study to propose evaluation of the normal range for TBS values in both genders in the Middle- East and Iran. According to our results: TBS ≤ 1.231 in men and TBS ≤ 1.287 in women is considered to be degraded microarchitecture among the Iranian population.