Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score
Claudie Berger, William D Leslie, Didier Hans
Lisa Langsetmo, David A Hanley, Christopher S Kovacs, Jerilynn C Prior, S M Kaiser, Kelly Davison, David Goltzman, Alexandra Papaioannou, K Shawn Davison, Robert G Josse, Stephanie M Kaiser, Suzanne N Morin, Gillian Mazzetti , Jonathan Adachi , CaMos Research Group
Trabecular bone score (TBS) is a gray-level texture measure derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images that predicts fractures independent of bone mineral density (BMD). Increased abdominal soft tissue in individuals with elevated body mass index (BMI) absorbs more X-rays during image acquisition for BMD measurement and must be accommodated by the TBS algorithm. We aimed to determine if the relationship between BMI and TBS varied between 2 major manufacturers' densitometers, because different densitometers accommodate soft tissues differently. We identified 1919 women and 811 men, participants of the Canadian Multicentre Osteoporosis Study, aged ≥40 yr with lumbar spine DXA scans acquired on GE Lunar (4 centers) or Hologic (3 centers) densitometers at year 10 of follow-up. TBS was calculated for L1-L4 (TBS iNsight® software, version 2.1). A significant negative correlation between TBS and BMI was observed when TBS measurements were performed on Hologic densitometers in men (Pearson r = -0.36, p <0.0001) and in women (Pearson r = -0.33, p <0.0001); significant correlations were not seen when TBS was measured on GE Lunar densitometers (Pearson r = 0.00 in men, Pearson r = -0.02 in women). Age-adjusted linear regression models confirmed significant interactions between BMI and densitometer manufacturer for both men and women (p < 0.0001). In contrast, comparable positive correlations were observed between BMD and BMI on both Hologic and GE Lunar densitometers in men and women. In conclusion, BMI significantly affects TBS values in men and women when measured on Hologic but not GE Lunar densitometers. This finding has implications for clinical and research applications of TBS, especially when TBS is measured sequentially on DXA densitometers from different manufacturers or when results from different machines are pooled for analysis.
trabecular bone score BMI densitometer differences, TBS lumbar spine DXA manufacturer comparison, body mass index effect on trabecular bone score, Hologic vs GE Lunar TBS measurement variability, Prior JC bone density DXA measurement, Canadian Multicentre Osteoporosis Study TBS, soft tissue artifact DXA bone score, trabecular bone score obesity correction algorithm, densitometer manufacturer specific TBS BMI correlation, bone mineral density body composition DXA imaging
PMID 28034592 28034592 DOI 10.1016/j.jocd.2016.11.003 10.1016/j.jocd.2016.11.003
Cite this article
Mazzetti, G., Berger, C., Leslie, W. D., Hans, D., Langsetmo, L., Hanley, D. A., Kovacs, C. S., Prior, J. C., Kaiser, S. M., Davison, K. S., Josse, R., Papaioannou, A., Adachi, J. R., Goltzman, D., Morin, S. N., & CaMos Research Group (2017). Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score. Journal of clinical densitometry : the official journal of the International Society for Clinical Densitometry, 20(2), 233-238. https://doi.org/10.1016/j.jocd.2016.11.003
Mazzetti G, Berger C, Leslie WD, Hans D, Langsetmo L, Hanley DA, et al. Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score. J Clin Densitom. 2017;20(2):233-238. doi:10.1016/j.jocd.2016.11.003
Mazzetti, G., et al. "Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score." Journal of clinical densitometry : the official journal of the International Society for Clinical Densitometry, vol. 20, no. 2, 2017, pp. 233-238.
The WHO fracture risk assessment tool (FRAX(®)) estimates an individual's 10-yr major osteoporotic and hip fracture probabilities. When bone mineral density (BMD) is included in the FRAX calculation, only the femoral neck measurement can be used. Recently, a procedure was reported for adjusting major osteoporotic fracture probability from FRAX with femoral neck BMD based on the difference (offset) between the lumbar spine and the femoral neck T-score values. The objective of the current analysis was to independently evaluate this algorithm in a population-based cohort of 4575 women and 1813 men aged 50 yr and older from the Canadian Multicentre Osteoporosis Study. For women and men combined, there was a 15% (95% confidence interval 7-24%) increase in major osteoporotic fracture risk for each offset T-score after adjusting for FRAX probability calculated with femoral neck BMD. The effect was stronger in women than men, but a significant sex interaction was not detected. Among the full cohort, 5.5% had their risk category reclassified after using the offset adjustment. Sexand age-dependent offsets (equivalent to an offset based on Z-scores) showed improved risk classification among individuals designated to be at moderate risk with the conventional FRAX probability measurement. In summary, the T-score difference between the lumbar spine and femoral neck is an independent risk factor for major osteoporotic fractures that is independent of the FRAX probability calculated with femoral neck BMD.
Bone HealthISCD GuidelinesPerimenopausal BMD ScreeningTechnical Standards
At the 2007 Position Development Conference, the Dual-Energy X-ray Absorptiometry Technical Task Force investigated three major areas of bone density testing. Although bone mineral density (BMD) testing in men had previously been reviewed at the 2005 Position Development Conference, we reviewed the most recent data in men to develop appropriate indications for bone density testing in men. We continue to recommend screening at age 70 and discuss the clinical risk factors that may be an appropriate indication for earlier BMD testing. Menopausal transition (perimenopause) was considered an important time to consider BMD evaluation because bone loss may be significant prior to menopause. However, because fracture risk is inherently low in women of this age without other risk factors, screening BMD testing is not appropriate. We discuss the risk factors that are strong indicators of fracture risk that may be increased during the menopause transition. The presence of these risk factors are appropriate indications for BMD testing with applicability of WHO diagnostic categorization. The issue of establishing a high threshold for BMD was investigated thoroughly and the current literature was reviewed. Despite the fact there is agreement that all BMD values greater than T-score -1.0 are not normal, it was felt that because of the paucity of sensitivity data and confounding factors such as high body mass index, an upper threshold could not be established or recommended at this time. This was felt to be an important area for further research.