The fracture predictive ability of lumbar spine BMD and TBS as calculated based on different combinations of the lumbar spine vertebrae

Effects of Lumbar Spine Vertebral Fractures on Trabecular Bone Score (TBS): The Manitoba BMD Registry

Trabecular bone score (TBS) is a BMD-independent risk factor for fracture. During BMD reporting, it is standard practice to exclude lumbar vertebral levels affected by structural artifact. It is uncertain whether TBS is affected by lumbar spine fractures. The current study examined the effect of lumbar spine compression fractures on TBS measurements. We identified 656 individuals with vertebral fractures (mean age 75.8 ± 7.9 years, 90.9% female) who had lumbar spine DXA, TBS measurements from L1-L4 and vertebral fracture assessment (VFA) for identifying vertebral fractures. There were 272 cases with lumbar spine fractures and 384 controls with only thoracic spine fractures. L1 TBS and BMD were significantly greater in those with than without lumbar fractures (p< 0.001) but did not significantly differ for other vertebral levels or for L1-L4 combined. TBS and BMD measurements were then renormalized to remove level-specific differences (denoted rTBS and rBMD). The mean difference (all fractured minus all non-fractured vertebrae) was +0.040 (+3.3%) for rTBS and +0.088 g/cm2 (+9.5%) for rBMD (both p <0.001). The largest effect was for L1 with mean difference +0.058 (+4.9%) for rTBS and +0.098 g/cm2 (+10.6%) for rBMD (both p <0.001). The mean difference between fractured and non-fractured levels for rTBS was +0.028 (+2.4%) for grade 1, +0.036 (+3.0%) for grade 2 and +0.059 (+5.0%) for grade 3 fractures; for rBMD +0.051 (+5.5%), +0.076 (+8.2%) and +0.151 (+16.4%) g/cm2, respectively. The impact of excluding lumbar vertebral levels with fracture from the L1-L4 TBS measurement overall was small (-0.011 [-1.0%]; p<0.001) and was also small for grade 3 fractures (-0.020 [-1.7%]; p<0.001). In summary, TBS is mildly increased by VFA-confirmed lumbar vertebral fractures, but the percentage effect is much smaller (less than half) than seen for BMD and minimally affects TBS measured from L1-L4. This would support the use of L1-L4 without exclusions in individuals with lumbar vertebral fractures.

Fracture Risk Associated with Different Numbers and Combinations of Lumbar Vertebrae: The Manitoba BMD Registry

Bone mineral density (BMD) is widely used for assessment of fracture risk. For the lumbar spine, BMD is typically measured from L1-L4 as it provides the largest area for assessment with the best measurement precision. Structural artifact often confounds spine BMD in clinical practice, and the International Society for Clinical Densitometry (ISCD) recommends removing vertebrae with artifact when reporting spine BMD. In its most recent position statements, the ISCD recommended against the use of a single vertebra when reporting spine BMD but stated that further studies should be done. The current analysis was performed to compare the performance of BMD from different numbers and combination of vertebral levels on fracture prediction in a large clinical registry of DXA tests for the Province of Manitoba, Canada. The study population comprised 39,727 individuals aged 40 years and older (mean age 62.7 years, 91.0 % female) with baseline DXA after excluding those with evidence of structural artifact. Mean follow-up for ascertaining fracture outcomes was 8.7 years. Area under the curve (AUC) for incident fracture risk stratification was statistically significant regardless of the BMD measurement site or fracture outcome. AUC differences with the various numbers and combinations of vertebral levels including a single vertebral body were small (less than or equal to 0.01). More substantial AUC differences were seen for femoral neck and total hip BMD versus L1-L4 BMD, approaching 0.1 for hip fracture stratification. In summary, we found that using combinations of fewer than 4 vertebrae including individual lumbar vertebrae predicted incident fractures. Importantly, differences between these different combinations were small when compared with L1-L4. Spine BMD was a better predictor of incident spine fracture compared to the hip, whereas the hip was better for hip fracture and overall fracture prediction.

Clinical Use of Trabecular Bone Score: The 2023 ISCD Official Positions

Osteoporosis can currently be diagnosed by applying the WHO classification to bone mineral density (BMD) assessed by dual-energy x-ray absorptiometry (DXA). However, skeletal factors other than BMD contribute to bone strength and fracture risk. Lumbar spine TBS, a grey-level texture measure which is derived from DXA images has been extensively studied, enhances fracture prediction independent of BMD and can be used to adjust fracture probability from FRAX® to improve risk stratification. The purpose of this International Society for Clinical Densitometry task force was to review the existing evidence and develop recommendations to assist clinicians regarding when and how to perform, report and utilize TBS. Our review concluded that TBS is most likely to alter clinical management in patients aged ≥ 40 years who are close to the pharmacologic intervention threshold by FRAX. The TBS value from L1-L4 vertebral levels, without vertebral exclusions, should be used to calculate adjusted FRAX probabilities. L1-L4 vertebral levels can be used in the presence of degenerative changes and lumbar compression fractures. It is recommended not to report TBS if extreme structural or pathological artifacts are present. Monitoring and reporting TBS change is unlikely to be helpful with the current version of the TBS algorithm. The next version of TBS software will include an adjustment based upon directly measured tissue thickness. This is expected to improve performance and address some of the technical factors that affect the current algorithm which may require modifications to these Official Positions as experience is acquired with this new algorithm.

FRAX® Adjustment Using Renormalized Trabecular Bone Score (TBS) from L1 Alone may be Optimal for Fracture Prediction: The Manitoba BMD Registry

Lumbar spine trabecular bone score (TBS) used in conjunction with FRAX® improves 10-year fracture prediction. The derived FRAX risk adjustment is based upon TBS measured from L1-L4, designated TBSL1-L4-FRAX. In prior studies, TBS measurements that include L1 and exclude L4 give better fracture stratification than L1-L4. We compared risk stratification from TBS-adjusted FRAX using TBS derived from different combinations of upper lumbar vertebral levels renormalized for level-specific differences in individuals from the Manitoba Bone Density Program aged >40 years with baseline assessment of TBS and FRAX. TBS measurements for L1-L3, L1-L2 and L1 alone were calculated after renormalization for level-specific differences. Corresponding TBS-adjusted FRAX scores designated TBSL1-L3-FRAX, TBSL1-L2-FRAX and TBSL1-FRAX were compared with TBSL1-L4-FRAX for fracture risk stratification. Incident major osteoporotic fractures (MOF) and hip fractures were assessed. The primary outcome was incremental change in area under the curve (ΔAUC). The study population included 71,209 individuals (mean age 64 years, 89.8% female). Before renormalization, mean TBS for L1-3, L1-L2 and L1 was significantly lower and TBS-adjusted FRAX significantly higher than from using TBSL1-L4. These differences were largely eliminated when TBS was renormalized for level-specific differences. During mean follow-up of 8.7 years 6745 individuals sustained incident MOF and 2039 sustained incident hip fractures. Compared with TBSL1-L4-FRAX, use of FRAX without TBS was associated with lower stratification (ΔAUC = -0.009, p < 0.001). There was progressive improvement in MOF stratification using TBSL1-L3-FRAX (ΔAUC = +0.001, p < 0.001), TBSL1-L2-FRAX (ΔAUC = +0.004, p < 0.001) and TBSL1-FRAX (ΔAUC = +0.005, p < 0.001). TBSL1-FRAX was significantly better than all other combinations for MOF prediction (p < 0.001). Incremental improvement in AUC for hip fracture prediction showed a similar but smaller trend. In conclusion, this single large cohort study found that TBS-adjusted FRAX performance for fracture prediction was improved when limited to the upper lumbar vertebral levels and was best using L1 alone.

Update on the clinical use of trabecular bone score (TBS) in the management of osteoporosis: results of an expert group meeting organized by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), and the International Osteoporosis Foundation (IOF) under the auspices of WHO Collaborating Center for Epidemiology of Musculoskeletal Health and Aging

PURPOSE

Trabecular bone score (TBS) is a grey-level textural measurement acquired from dual-energy X-ray absorptiometry lumbar spine images and is a validated index of bone microarchitecture. In 2015, a Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) published a review of the TBS literature, concluding that TBS predicts hip and major osteoporotic fracture, at least partly independent of bone mineral density (BMD) and clinical risk factors. It was also concluded that TBS is potentially amenable to change as a result of pharmacological therapy. Further evidence on the utility of TBS has since accumulated in both primary and secondary osteoporosis, and the introduction of FRAX and BMD T-score adjustment for TBS has accelerated adoption. This position paper therefore presents a review of the updated scientific literature and provides expert consensus statements and corresponding operational guidelines for the use of TBS.

METHODS

An Expert Working Group was convened by the ESCEO and a systematic review of the evidence undertaken, with defined search strategies for four key topics with respect to the potential use of TBS: (1) fracture prediction in men and women; (2) initiating and monitoring treatment in postmenopausal osteoporosis; (3) fracture prediction in secondary osteoporosis; and (4) treatment monitoring in secondary osteoporosis. Statements to guide the clinical use of TBS were derived from the review and graded by consensus using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

A total of 96 articles were reviewed and included data on the use of TBS for fracture prediction in men and women, from over 20 countries. The updated evidence shows that TBS enhances fracture risk prediction in both primary and secondary osteoporosis, and can, when taken with BMD and clinical risk factors, inform treatment initiation and the choice of antiosteoporosis treatment. Evidence also indicates that TBS provides useful adjunctive information in monitoring treatment with long-term denosumab and anabolic agents. All expert consensus statements were voted as strongly recommended.

CONCLUSION

The addition of TBS assessment to FRAX and/or BMD enhances fracture risk prediction in primary and secondary osteoporosis, adding useful information for treatment decision-making and monitoring. The expert consensus statements provided in this paper can be used to guide the integration of TBS in clinical practice for the assessment and management of osteoporosis. An example of an operational approach is provided in the appendix. This position paper presents an up-to-date review of the evidence base, synthesised through expert consensus statements, which informs the implementation of Trabecular Bone Score in clinical practice.

Trabecular Bone Score Vertebral Exclusions Affect Risk Classification and Treatment Recommendations: The Manitoba Bmd Registry

Lumbar spine trabecular bone score (TBS), a texture measure derived from spine dual-energy x-ray absorptiometry (DXA) images, is a bone mineral density (BMD)-independent risk factor for fracture. Lumbar vertebral levels that show structural artifact are excluded from BMD measurement. TBS is relatively unaffected by degenerative artifact, and it is uncertain whether the same exclusions should be applied to TBS reporting. To gain insight into the clinical impact of vertebral exclusion on TBS, we examined the effect of lumbar vertebral exclusions in routine clinical practice on tertile-based TBS categorization and TBS adjusted FRAX-based treatment recommendations. The study population consisted of 71,209 individuals aged 40 years and older with narrow fan-beam spine DXA examinations and retrospectively-derived TBS. During BMD reporting, 34.3% of the scans had one or more vertebral exclusions for structural artifact. When TBS was derived from the same vertebral levels used for BMD reporting, using fixed L1-L4 tertile cutoffs (1.23 and 1.31 from the McCloskey meta-analysis) reclassified 17.9% to a lower and 6.5% to a higher TBS category, with 75.6% unchanged. Reclassification was reduced from 24.4% overall to 17.2% when level-specific tertile cutoffs from the software manufacturer were used. Treatment reclassification based upon FRAX major osteoporotic fracture probability occurred in 2.9% overall, but in 9.6% of those with baseline risk ≥15%. For treatment based upon FRAX hip fracture probability, reclassification occurred in 3.4% overall, but in 10.4% in those with baseline risk ≥2%. In summary, lumbar spine TBS measurements based upon vertebral levels other than L1-L4 can alter the tertile category and treatment recommendations based upon TBS-adjusted FRAX calculation, especially for those close to or exceeding the treatment cut-off. Manufacturer level-specific tertile cut-offs should be used if vertebral exclusions are applied.

Vertebral Level Variations in Trabecular Bone Score and Effect on Fracture Prediction: The Manitoba BMD Registry

Trabecular bone score (TBS), a texture measure derived from spine dual-energy x-ray absorptiometry (DXA) images, is a bone mineral density (BMD)-independent risk factor for fracture. TBS is reportedly insensitive to degenerative changes, and it is uncertain whether the same rules for excluding lumbar vertebral levels from BMD measurement should be applied to TBS. The current analysis was performed to explore inter-vertebral variation in TBS measurements from L1 to L4, how this relates to clinically identified structural artifact resulting in vertebral level exclusion from BMD reporting, and area under the curve (AUC) for incident fracture. The study population comprised 70,762 individuals aged 40 years and older at the time of baseline spine DXA assessment (mean age 64.1 years, 89.7% female), among whom 24,289 (34.3%) had one or more vertebral exclusions. Both TBS and BMD showed a similar cranial/caudal inter-vertebral gradient. Compared with L1-4, TBS from L1 alone was lower (mean difference -0.096; -7.6%) while TBS from L4 alone was 0.046 (3.6%) greater, similar in those without and with visual structural artifact. During mean follow-up of 8.7 years, 6744 (9.5%) individuals sustained incident major osteoporotic fractures. TBS from L1 alone gave significantly higher AUC for incident fracture than L1-4, which was in turn significantly higher than L2, L3 and L4 alone, seen in those without and with visual structural artifact. In contrast, AUCs for BMD showed minimal variation from L1 to L4, and was higher for L1-4 than for any individual lumbar vertebral level. In summary, we found inter-vertebral TBS variations within the lumbar spine are overall similar to BMD but are relatively unaffected by visual structural artifact. Fracture outcomes showed the strongest association with TBS measured from L1 alone. Further investigation is need to understand the cause and clinical application of these differences.

Subsequent Domino Osteoporotic Vertebral Fractures Adversely Affect Short-Term Health-Related Quality of Life: A Prospective Multicenter Study

Background and Objectives: Conservative treatment is the gold standard for acute osteoporotic vertebral fractures (AOVFs). However, the treatment strategy for multiple AOVFs remains unknown. We conducted a prospective study using magnetic resonance imaging (MRI) to investigate how rapidly subsequent osteoporotic vertebral fractures (OVFs) occur as domino OVFs within 3 months. This study aimed to assess the incidence and impact of domino OVFs on quality of life (QOL) following conservative treatment for initial AOVFs. Materials and Methods: A prospective multicenter cohort study was conducted at eight hospitals. The included patients were those with AOVFs occurring within 3 weeks, aged >60 years, and diagnosed using MRI. All patients were treated conservatively and underwent MRI after 3 months. Subsequent domino OVFs were defined as newly occurring OVFs within 3 months. Patient characteristics, types of conservative treatment, and patient-reported outcomes, including a visual analogue scale (VAS), the Oswestry disability index (ODI), and the Japanese Orthopaedic Association back pain evaluation questionnaire (JOABPEQ), were evaluated and compared between the domino OVF and non-domino OVF groups. Results: A total of 227 patients were analyzed. The mean age was 80.1 ± 7.3 years and 78% were female. Subsequent domino OVFs were observed in 31 (13.6%) patients within 3 months. An increasing number of prevalent OVFs were significantly associated with domino OVFs (p = 0.01). No significant differences in bone mineral density, type of brace, and anti-osteoporosis medications were found between the two groups. The JOABPEQ (excluding social function), ODI, and VAS were significantly improved after 3 months. Patients with domino OVFs at 3 months had poorer JOABPEQ social life function, ODI, and VAS than those with non-domino OVFs. Conclusions: In this study, the incidence of domino OVFs was 13.6% within 3 months. Domino OVFs had a negative impact on QOL at 3 months and were associated with prevalent OVFs.

Bone Health Status in Individuals with Amyotrophic Lateral Sclerosis: A Cross-Sectional Study on the Role of the Trabecular Bone Score and Its Implications in Neurorehabilitation

Background and Objectives: Osteoporosis is a metabolic skeletal disease resulting in low bone mass with increased bone fragility and susceptibility to fractures. May lead to rapid loss of bone mineral density (BMD) due to physical inactivity and reduced muscle contractions. Generally, the diagnosis of osteoporosis is made using dual X-ray absorptiometry (DXA), by measuring BMD and the trabecular bone score (TBS), which can be useful for detecting bone fragility and susceptibility to fractures. Therefore, the aim of this study was to investigate, using BMD and TBS, the bone health status in a sample of amyotrophic lateral sclerosis (ALS) inpatients attending neurorehabilitation. Materials and Methods: Thirty-nine patients were included in the study and underwent electrocardiogram and blood tests, including calcium and parathyroid hormone, as well as vitamin D dosage, and DXA. Results: We found that the TBS of patients with osteoporosis was lower than that of those ALS patients with osteopenia or normal bone status, both in the lumbar spine and femoral neck, although no statistical significance was reached. In addition, Spearman's correlation coefficient indicated a moderate correlation between TBS and lumbar spine BMD (r = -0.34) and a mild correlation between TBS and femoral neck BMD (r = -0.28). Conclusions: This study confirmed the hypothesis that ALS patients may exhibit deteriorated bone health with lower bone density and focused on the possible role of the TBS in the multidisciplinary approach to ALS.