Original Article

Osteoporosis International

, Volume 17, Issue 4, pp 527-534

First online:

The use of multiple sites for the diagnosis of osteoporosis

  • J. A. KanisAffiliated withWHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School Email author 
  • , O. JohnellAffiliated withDepartment of Orthopaedics, Malmo University Hospital
  • , A. OdenAffiliated withConsulting Statistician
  • , H. JohanssonAffiliated withConsulting Statistician
  • , J. A. EismanAffiliated withBone & Mineral Research, Garvan Institute of Medical Research
  • , S. FujiwaraAffiliated withRadiation Effects Research Foundation
  • , H. KrogerAffiliated withDepartment of Surgery Bone & Cartilage Research Unit, Kuopio University Hospital
  • , R. HonkanenAffiliated withDepartment of Surgery Bone & Cartilage Research Unit, Kuopio University Hospital
  • , L. J. MeltonIIIAffiliated withDivision of Epidemiology, Mayo Clinic
    • , T. O’NeillAffiliated withARC Epidemiology Research Unit, University of Manchester
    • , J. ReeveAffiliated withInstitute of Public Health and Department of Medicine
    • , A. SilmanAffiliated withARC Epidemiology Research Unit, University of Manchester
    • , A. TenenhouseAffiliated withDivision of Bone Metabolism, The Montreal General Hospital

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Abstract

Introduction

It has been suggested that bone mineral density (BMD) measurements should be made at multiple sites, and that the lowest T–score should be taken for the purpose of diagnosing osteoporosis.

Purpose

The aim of this study was to examine the use of BMD measurements at the femoral neck and lumbar spine alone and in combination for fracture prediction.

Methods

We studied 19,071 individuals (68% women) from six prospective population-based cohorts in whom BMD was measured at both sites and fracture outcomes documented over 73,499 patient years. BMD values were converted to Z-scores, and the gradient of risk for any osteoporotic fracture and for hip fracture was examined by using a Poisson model in each cohort and each gender separately. Results of the different studies were merged using weighted β-coefficients.

Results

The gradients of risk for osteoporotic fracture and for hip fracture were similar in men and women. In men and women combined, the risk of any osteoporotic fracture increased by 1.51 [95% confidence interval (CI)=1.42–1.61] per standard deviation (SD) decrease in femoral-neck BMD. For measurements made at the lumbar spine, the gradient of risk was 1.47 (95% CI=1.38–1.56). Where the minimum of the two values was used, the gradient of risk was similar (1.55; 95% CI=1.45–1.64). Higher gradients of risk were observed for hip fracture outcomes: with BMD at the femoral neck, the gradient of risk was 2.45 (95% CI=2.10–2.87), with lumbar BMD was 1.57 (95% CI=1.36–1.82), and with the minimum value of either femoral neck and lumbar spine was 2.11 (95% CI=1.81–2.45). Thus, selecting the lowest value for BMD at either the femoral neck or lumbar spine did not increase the predictive ability of BMD tests. By contrast, the sensitivity increased so that more individuals were identified but at the expense of specificity. Thus, the same effect could be achieved by using a less stringent T–score for the diagnosis of osteoporosis.

Conclusions

Since taking the minimum value of the two measurements does not improve predictive ability, its clinical utility for the diagnosis of osteoporosis is low.

Keywords

BMD Bone strength Collagen Fracture prediction