Age-related Normative Values of Trabecular Bone Score (TBS) for Japanese Women: the Japanese Population-based Osteoporosis (JPOS) Study

Summary Trabecular bone score (TBS), a surrogate measure of bone microarchitecture, represents fracture risk independently of bone density. We present normative TBS values from a representative population study of Japanese women. This database would enhance our understanding of trabecular bone microarchitecture and improve osteoporosis management. Introduction TBS is a texture parameter that quantifies local variation in gray level distribution within dual-energy X-ray absorptiometry (DXA) images of the lumbar spine. While TBS is associated with fracture risk independently of areal bone mineral density (aBMD), normative TBS values have only been reported for Caucasian women. This study provides age-specific normative values of TBS from a representative sample of Japanese women. Methods We randomly selected 4,550 women aged 15–79 years from 7 areas throughout Japan. Women younger than 20 years and those with any medical history which might affect bone metabolism were excluded, and the remaining 3,069 with at least two assessable vertebrae from the first to the fourth vertebrae were subjected to analysis. TBS values were calculated from spine DXA images using TBS iNsight software (Med-Imaps, France). Age-related models of TBS were constructed using piecewise linear regression analysis. Results Participant age, body mass index (BMI), spine aBMD, and TBS (mean ± SD) were 48.7 ± 16.8 years, 22.9 ± 3.4, 0.888 ± 0.169 g/cm 2 , and 1.187 ± 0.137, respectively. A three-piece linear regression model of TBS on age explained 70.7 % of the total variance in TBS and comprised very small age-related changes in the youngest segment of the regression line, rapid loss in the middle segment, and small loss in the oldest segment. TBS was lower in Japanese women than in Caucasian women across all age ranges, with the difference increasing with age up through 65 years. Conclusions The normative values of TBS for Japanese women presented here would enhance our understanding of trabecular bone microarchitecture and help improve the management of osteoporosis.