Available online 2 May 2024, 101502

Author links open overlay panel, Abstract

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.

Section snippetsINTRODUCTION

Bone mineral density (BMD) from dual-energy x-ray absorptiometry (DXA) has been used for over 30 years in the assessment of osteoporosis1. There is consistent evidence that BMD predicts fracture risk2, 3, 4, 5. For the lumbar spine, BMD measured from L1-L4 is preferred for clinical reporting as it provides the largest area for assessment with the best measurement precision6. However, structural artifact often confounds spine BMD in clinical practice with degenerative change the most common

Study population

In Canada, there is a single public health care system that provides services including DXA testing to nearly all residents. The Manitoba Density Program provided DXA testing as an integrated program since 199715. The Manitoba Density Program maintains a database of all DXA results that can be linked with other population-based databases through an anonymous personal identifier16. The study cohort consisted of all individuals aged 40 years and older with baseline spine and hip DXA assessment

Study population

Table 1 summarizes the baseline characteristics of the patients. The cohort studied consisted of 39727 individuals, mean age 62.7 years, with 91% female. Mean follow-up for ascertaining fracture outcomes was 8.7 years, during which 4809 (12.1%) of the individuals sustained one or more incident fractures, including 3,600 (9.1%) with one or more incident MOF (933 clinical spine, 1085 hip, 1296 forearm and 913 humerus).

BMD T-score differences

Table 2 compares the mean T-score for the various BMD sites in those with

DISCUSSION

This study confirmed that BMD measured at the lumbar spine (L1-L4), femoral neck and total hip stratifies risk for a range of fracture outcomes2, 3, 4, 5. Moreover, deriving BMD from fewer than 4 vertebral bodies and from even a single vertebral body also significantly stratified fracture risk. The incremental difference in AUC between using L1-L4 and other combinations of fewer than 4 lumbar vertebrae was small (less than or equal to 0.01). Total hip and femoral neck BMD outperformed spine BMD

Roles

Authors' roles: conception, design, data analysis (WDL); first draft of the article (FZ); interpretation of data (All Authors); critically revising the article for important intellectual content (All Authors); final approval of the version to be published (All Authors); agreement to be accountable for all aspects of the work (All Authors). WDL had full access to all the data in the study and takes the responsibility for the integrity of the data and the accuracy of the data analysis.

Declaration of competing interest

Fatima Zarzour and William Leslie declare no conflict of interest.

Funding

This study had no external funding body.

Acknowledgments

The authors acknowledge the Manitoba Centre for Health Policy for use of data contained in the Population Health Research Data Repository (HIPC 2016/2017- 29). The results and conclusions are those of the authors and no official endorsement by the Manitoba Centre for Health Policy, Manitoba Health, Healthy Living, and Seniors, or other data providers is intended or should be inferred. This article has been reviewed and approved by the members of the Manitoba Bone Density Program Committee.

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© 2024 The International Society for Clinical Densitometry. Published by Elsevier Inc.