Dr Leslie has received speaker fees, research honoraria, and grants from Merck Frosst Canada, in addition to honoraria and grants from Sanofi-Aventis and Procter & Gamble Pharmaceuticals Canada. All other authors state that they have no conflicts of interest.
Number of Osteoporotic Sites and Fracture Risk Assessment: A Cohort Study From the Manitoba Bone Density Program†
Article first published online: 4 DEC 2006
Copyright © 2007 ASBMR
Journal of Bone and Mineral Research
Volume 22, Issue 3, pages 476–483, March 2007
How to Cite
Leslie, W. D., Tsang, J. F., Caetano, P. A., Lix, L. M. and for the Manitoba Bone Density Program (2007), Number of Osteoporotic Sites and Fracture Risk Assessment: A Cohort Study From the Manitoba Bone Density Program. J Bone Miner Res, 22: 476–483. doi: 10.1359/jbmr.061112
- Issue published online: 4 DEC 2009
- Article first published online: 4 DEC 2006
- Manuscript Accepted: 29 NOV 2006
- Manuscript Revised: 23 OCT 2006
- Manuscript Received: 27 AUG 2006
- bone densitometry;
- epidemiology—population studies;
- fracture prediction
Site-discordance in BMD assessment is common and significantly affects patient categorization. Greater number of osteoporotic sites correlates with lower T scores at each index site. This largely explains the positive association between number of osteoporotic sites and fracture risk.
Introduction: Site-discordance in BMD is common when used to classify patients based on a cut-off T score of −2.5. It is unclear whether fracture risk assessment is improved by considering BMD information from multiple sites. Our objective was to assess the contribution of number of osteoporotic sites to overall fracture risk.
Materials and Methods: The study population was drawn from the regionally based clinical database of the Manitoba Bone Density Program that includes all clinical DXA test results for the Province of Manitoba, Canada. Analyses were limited to 16,505 women ≥50 years of age at the time of baseline DXA of the spine (L1–L4) and hip (three sites). During follow-up (3.2 ± 1.5 years), longitudinal health service records showed 765 women with at least one osteoporotic fracture code (hip, forearm, spine, or humerus).
Results: Of 5012 women classified as osteoporotic by at least one site (T score −2.5 or lower), almost one half (2370; 47%) were abnormal at only a single site. Among the 1856 women with an osteoporotic total hip measurement, mean total hip T scores decreased as the number of additional osteoporotic sites increased (−2.58, no other osteoporotic sites; −2.69, one other site; −2.87, two other sites; −3.17, three other sites; Spearman r = −0.44, p < 0.0001). Age-adjusted fracture risk from a Cox proportional hazards model increased as the number of osteoporotic sites increased (p < 0.0001), but number of osteoporotic sites was no longer an independent predictor after total hip BMD was included as a covariate (p = 0.19). Covariate adjustment for other sites of BMD measurement attenuated, but did not eliminate, the effect of number of osteoporotic sites.
Conclusions: Site-discordance is common and significantly affects patient categorization when different skeletal sites are used for diagnosis. Greater number of osteoporotic sites correlates with lower T scores at each index site. This largely explains the positive association between number of osteoporotic sites and fracture risk.