Establishing a Regional Bone Density Program: Lessons From the Manitoba Experience

doi:10.1385/JCD:6:3:275

Journal of Clinical Densitometry

Volume 6, Issue 3, Autumn 2003, Pages 275-282

https://doi.org/10.1385/JCD:6:3:275 Get rights and content

Abstract

In 1997, the province of Manitoba, Canada developed a regional bone density program to address concerns related to access, waiting times, and quality assurance. We report our experience with this model of bone density service delivery, which is unique in North America, and confront the challenge of balancing accessibility, clear guidelines, and fiscal responsibility.

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Cited by (143)

Estimating Lumbar Spine Least Significant Change for Fewer than Four Vertebrae: The Manitoba BMD Registry
2024, Journal of Clinical Densitometry
Introduction: The International Society of Clinical Densitometry recommends omitting lumbar vertebrae affected by structural artifact from spine BMD measurement. Since reporting fewer than 4 vertebrae reduces spine BMD precision, least significant change (LSC) needs to be adjusted upwards when reporting spine BMD change based on fewer than 4 vertebrae.
Methodology: In order to simplify estimating LSC from combinations of vertebrae other than L1-L4 (denoted LSC_L1-4 ), we analyzed 879 DXA spine scan-pairs from the Manitoba BMD Program's ongoing precision evaluation. The additional impact on the LSC of performing the second scan on the same day vs different day was also assessed.
Results: LSC progressively increased when fewer vertebrae were included, and also increased when the scans were performed on different days. We estimated that the LSC_L1-4 should be adjusted upwards by 7 %, 24 % and 65 % to approximate the LSC for 3, 2, or 1 vertebral body, respectively. To additionally capture the greater LSC when the precision study was done on different days, LSC_L1-4 derived from a precision study where scans were done on the same day should be adjusted upwards by 39 %, 60 % and 112 % for 3, 2, or 1 vertebral body, respectively.
Conclusion: LSC_L1-4 derived from a precision study where scans are performed on the same day can be used to estimate LSC for fewer than 4 vertebrae and for scans performed on different days.
Effects of severe lumbar spine structural artifact on trabecular bone score (TBS): The Manitoba BMD Registry
2023, Journal of Clinical Densitometry
Trabecular bone score (TBS) is a bone mineral density (BMD)-independent risk factor for fracture. During DXA analysis and BMD reporting, it is standard practice to exclude lumbar vertebral levels affected by structural artifact. Although TBS is relatively insensitive to degenerative artifact, it is uncertain whether TBS is still useful in the presence extreme structural artifact that precludes reliable spine BMD measurement even after vertebral exclusions. Among individuals aged 40 years and older undergoing baseline DXA assessment from September 2012 to March 2018 we identified three mutually exclusive groups: spine BMD reporting performed without exclusions (Group 1, N=12,865), spine BMD reporting performed with vertebral exclusions (Group 2, N=4867), and spine BMD reporting not performed due to severe structural artifact (Group 3, N=1541). No significant TBS difference was seen for Group 2 versus Group 1 (referent), whereas TBS was significantly greater in Group 3 (+0.041 partially adjusted, +0.043 fully adjusted). When analyzed by the reason for vertebral exclusion, multilevel degenerative changes significantly increased TBS (+0.041 partially adjusted, +0.042 fully adjusted), while instrumentation significantly reduced TBS (-0.059 partially adjusted, -0.051 fully adjusted). Similar results were seen when analyses were restricted to those in Group 3 with a single reason for vertebral exclusions, and when follow up scans were also included. During mean follow-up of 2.5 years there were 802 (4.2 %) individuals with one or more incident fractures. L1-L4 TBS showed significant fracture risk stratification in all groups including Group 3 (P-interaction >0.4). In conclusion, lumbar spine TBS can be reliably measured in the majority of lumbar spine DXA scans, including those with artifact affecting up to two vertebral levels. However, TBS is significantly affected by the presence of extreme structural artifact in the lumbar spine, especially those with multilevel degenerative disc changes and/or instrumentation that precludes reliable BMD reporting.
FRAX® adjustment using renormalized trabecular bone score (TBS) from L1 alone may be optimal for fracture prediction: The Manitoba BMD registry
2023, Journal of Clinical Densitometry
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 TBS_L1-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 TBS_L1-L3-FRAX, TBS_L1-L2-FRAX and TBS_L1-FRAX were compared with TBS_L1-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 TBS_L1-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 TBS_L1-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 TBSL_1-L3-FRAX (ΔAUC = +0.001, p < 0.001), TBS_L1-L2-FRAX (ΔAUC = +0.004, p < 0.001) and TBS_L1-FRAX (ΔAUC = +0.005, p < 0.001). TBS_L1-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.
Adjusting Trabecular Bone Score (TBS) for level-specific differences reduces FRAX®-based treatment reclassification in patients with vertebral exclusions: The Manitoba BMD Registry
2023, Journal of Clinical Densitometry
Trabecular bone score (TBS) is a FRAX®-independent risk factor for fracture prediction. TBS values increase from cranial to caudal, with the following mean differences between TBS_L1-L4 and individual lumbar vertebrae: L1 −0.093, L2 −0.008, L3 +0.055 and L4 +0.046. Excluding vertebral levels can affect FRAX-based treatment recommendations close to the intervention threshold. We examined the effect of adjusting for level-specific TBS differences in individuals with vertebral exclusions due to structural artifact on TBS-adjusted FRAX-based treatment recommendations. We identified 71,209 individuals aged ≥40 years with TBS and FRAX calculations through the Manitoba Bone Density Program. In the 24,428 individuals with vertebral exclusions, adjusting TBS using these level-specific factors agreed with TBS_L1-L4 (mean difference −0.001). We compared FRAX-based treatment recommendations for TBS_L1-L4 and for non-excluded vertebral levels before and after adjusting for level-specific TBS differences. Among those with baseline major osteoporotic fracture risk ≥15 %, TBS with vertebral exclusions reclassified FRAX-based treatment in 10.6 % of individuals compared with TBS_L1-L4, and was reduced to 7.2 % after adjusting for level-specific differences. In 11,131 patients where L1–L2 was used for BMD reporting (the most common exclusion pattern with the largest TBS effect), treatment reclassification was reduced from 13.9 % to 2.4 %, respectively. Among individuals with baseline hip fracture risk ≥2 %, TBS vertebral exclusions reclassified 7.1 % compared with TBS_L1-L4, but only 4.5 % after adjusting for level-specific differences. When L1–L2 was used for BMD reporting, treatment reclassification from hip fracture risk was reduced from 9.2 % to 5.2 %. In conclusion, TBS and TBS-adjusted FRAX-based treatment recommendations are affected by vertebral level exclusions for structural artifact. Adjusting for level-specific differences in TBS reduces reclassification in FRAX-based treatment recommendations.
Trabecular Bone Score Vertebral Exclusions Affect Risk Classification and Treatment Recommendations: The Manitoba Bmd Registry
2023, Journal of Clinical Densitometry
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.
FRAX Adjustment by Trabecular Bone Score with or Without Bone Mineral Density: The Manitoba BMD Registry
2023, Journal of Clinical Densitometry
Trabecular bone score (TBS), a texture measure derived from spine dual-energy x-ray absorptiometry (DXA) images, is a FRAX®-independent risk factor for fracture. The TBS adjustment to FRAX assumes the presence of femoral neck BMD in the calculation. However, there are many individuals in whom hip DXA cannot be acquired. Whether the TBS-adjustment would apply to FRAX probabilities calculated without BMD has not been studied. The current analysis was performed to evaluate major osteoporotic fracture (MOF) and hip fracture risk adjusted for FRAX with and without femoral neck BMD. The study cohort consisted of 71,209 individuals (89.8% female, mean age 64.0 years). During mean follow-up 8.7 years, 6743 (9.5%) individuals sustained one or more incident MOF, of which 2037 (2.9%) sustained a hip fracture. Lower TBS was significantly associated with increased fracture risk when adjusted for FRAX probabilities, with a slightly larger effect when BMD was not included. Inclusion of TBS in the risk calculation gave a small but significant increase in stratification for fracture probabilities estimated with and without BMD. Calibration plots showed very minor deviations from the line of identity, indicating overall good calibration. In conclusion, the existing equations for incorporating TBS in FRAX estimates of fracture probability work similarly when femoral neck BMD is not used in the calculation. This potentially extends the range of situations where TBS can be used clinically to those individuals in whom lumbar spine TBS is available but femoral neck BMD is not available.

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Original ArticleEstablishing a Regional Bone Density Program: Lessons From the Manitoba Experience

Abstract

Soc Sci Med

J Am Coll Cardiol

Registries and administrative data: organization and accuracy

Med Care

Short-term mortality after repair of hip fracture. Do Manitoba elderly do worse?

Med Care

Risk factors for hip fracture in white women

New Engl J Med

An assessment tool for predicting fracture risk in postmenopausal women

Osteoporos Int

Quality control of DXA instruments in multicenter trials

Osteoporos Int

Bone mineral density testing in healthy postmenopausal women. The role of clinical risk factor assessment in determining fracture risk

J Clin Densitom

Original Article
Establishing a Regional Bone Density Program: Lessons From the Manitoba Experience