The effects of standardization and reference values on patient classification for spine and femur dual-energy X-ray absorptiometry

The effect of two methods for standardizing dual-energy X-ray absorptiometry (DXA) measurements on patient classification by the T-score has been determined for a group of over 2000 patients. The methods proposed by the International DXA Standardization Committee and the European Community's CO...

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Bibliographic Details
Published in:Osteoporosis international 1997-01, Vol.7 (3), p.200-206
Main Authors: SIMMONS, A, SIMPSON, D. E, O'DOHERTY, M. J, BARRINGTON, S, COAKLEY, A. J
Format: Article
Language:English
Subjects:
Absorptiometry, Photon - standards
Adult
Aged
Aged, 80 and over
Biological and medical sciences
Bone Density
Bones
Diseases of the osteoarticular system
Female
Femur Neck - physiopathology
Humans
Medical sciences
Middle Aged
Older people
Osteoporosis
Osteoporosis - physiopathology
Osteoporosis. Osteomalacia. Paget disease
Reference Values
Spine - physiopathology
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Summary:The effect of two methods for standardizing dual-energy X-ray absorptiometry (DXA) measurements on patient classification by the T-score has been determined for a group of over 2000 patients. The methods proposed by the International DXA Standardization Committee and the European Community's COMAC-BME group were used in conjunction with young reference data from the major DXA manufacturers, the COMAC-BME group and the third US National Health and Nutrition Examination Survey (NHANES III). The two standardization techniques produced dissimilar classifications as measured by the kappa statistic (kappa = 0.34-0.90), especially for the femoral neck, with up to 24.3% of patients reclassified from osteopenic to normal and 18.6% reclassified from osteoporotic to osteopenic when the standardization method was changed. Considering the effects of both reference data and standardization techniques together, there was a wide variation of patient classification, with the number of patients classified as osteoporotic varying from 9.6% to 21.1% for the postero-anterior spine L2-4 region and from 2.3% to 27.6% for the femoral neck. The agreement between different classifications ranged widely, from very poor to excellent (kappa = 0.02-0.98). The creation of standardized reference data must be an important priority in order to harmonize patient management using standardized BMD measurements. The choice of standardization technique, however, must be addressed in light of the results presented here.
ISSN:0937-941X
1433-2965
DOI:10.1007/BF01622289