Trabecular Bone Score (TBS) Varies with Correction for Tissue Thickness Versus Body Mass Index: Implications When...

Area of Science:

• Pediatric Bone Health
• Radiology and Imaging
• Biomedical Engineering

Background:

• Trabecular bone score (TBS) enhances fracture prediction beyond bone mineral density (BMD) in adults.
• Pediatric TBS norms were previously unavailable, limiting its use in younger populations.
• The Bone Mineral Density in Childhood Study (BMDCS) provided robust TBS reference data for youth.

Purpose of the Study:

• To investigate the differences between two TBS algorithms (TBS_TH and TBS_BMI) in healthy youth.
• To assess the clinical implications of using different TBS algorithms for pediatric fracture risk assessment.
• To determine if TBS_BMI values can be converted to TBS_TH equivalents for use with existing pediatric norms.

Main Methods:

• Analysis of TBS values from 189 healthy youth using both TBS_TH (tissue thickness) and TBS_BMI (BMI-adjusted) algorithms.
• Comparison of TBS values between the two algorithms across different age groups, pubertal stages, and BMI Z-scores.
• Evaluation of the systematic differences and their impact on TBS Z-score calculations using BMDCS reference data.

Main Results:

• Both TBS algorithms showed similar increases with age and pubertal development.
• TBS_BMI values were systematically and significantly higher than TBS_TH values (mean difference = 0.06, p < 0.0001).
• Differences between algorithms were non-uniform, being greater in males, older individuals, later Tanner stages, and higher BMI Z-scores, precluding simple conversion.

Conclusions:

• Systematic differences between TBS_BMI and TBS_TH algorithms in youth prevent direct use of TBS_BMI with TBS_TH pediatric reference data.
• Using TBS_BMI with TBS_TH reference norms results in falsely elevated TBS Z-scores (mean difference = 0.73).
• BMDCS TBS reference norms should not be applied with TBS_BMI until TBS_TH software is commercially available for Hologic DXA equipment.