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Osteoporosis International

, Volume 11, Issue 10, pp 852–857 | Cite as

Site-Specific Variation in the Classification of Osteoporosis, and the Diagnostic Reclassification Using the Lowest Individual Lumbar Vertebra T-score Compared with the L1–L4 Mean, in Early Postmenopausal Women

  • O. Sahota
  • D. Pearson
  • S. W. Cawte
  • P. San
  • D. J. Hosking
Original Article

Abstract:

In this study we report first the concordance and variation in diagnostic osteoporosis classification using multiple skeletal site measurements compared with the lumbar spine only; and secondly, at the lumbar spine, the variation and diagnostic osteoporosis reclassification using the lowest individual vertebra T-score compared with the L1–L4 mean T-score. One hundred and fifty early postmenopausal women were evaluated as part of the recruitment for a multicenter osteoporosis prevention study. Bone mineral density (BMD) was restricted such that no more than 10% of the subjects had a lumbar spine BMD below 0.8 g/cm2. Forty-seven per cent of the subjects were classified as having low bone mass (T-score ≤−1.0) at the lumbar spine, 63% at the mid-forearm, 39% at the distal forearm and 50% at the hip (p<0.05). The greatest proportion of subjects were categorized as osteoporotic at the lumbar spine, followed by the forearm and then the hip. Correlation between sites ranged from 0.57 to 0.60 (p<0.01). Eighty-one percent of the subjects had a significant difference between their highest and lowest individual lumbar vertebra T-score (defined as a difference outside the 90% confidence interval coefficient of variation T-score value). Using the lowest individual lumbar T-score, recategorized 33% of the subjects classified as osteopenic (based on the mean L1–L4 T-score) as osteoporotic, and 23% of those classified as normal as osteopenic (p<0.05). Of all four vertebrae, L2 had the highest T-score in 37.7% of the subjects (mean −0.3) and L4 the lowest in 61% (mean −1.5) (mean difference 1.2 units, 95% CI 0.7 to 1.7). The classification of osteoporosis varies according to skeletal site, with pronounced differences in the early menopausal population. T-scores are useful for characterizing subjects with the highest risk of osteoporosis but BMD and fracture risk must be recognized in a continuum. Individual T-scores of the lumbar vertebrae show wide variation in the absence of degenerative spinal disease or vertebral collapse and the use of the lowest, significantly different, individual lumbar vertebra T-score reclassified over half of the subjects in this study. This poses a great therapeutic dilemma in clinical practice, particularly if these fractures are at higher risk of future collapse.

Key words:Osteoporosis classification – Postmenopausal women – Skeletal sites –T-score 

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Copyright information

© International Osteoporosis Foundation and National Osteoporosis Foundation 2000

Authors and Affiliations

  • O. Sahota
    • 1
  • D. Pearson
    • 3
  • S. W. Cawte
    • 4
  • P. San
    • 2
  • D. J. Hosking
    • 2
  1. 1.Ageing and Disability Research Unit (ADRU), University Hospital, Nottingham;GB
  2. 2.Division of Mineral MetabolismGB
  3. 3.Department of Medical PhysicsGB
  4. 4.Department of Nuclear Medicine, City Hospital, Nottingham, UKGB

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