title: Detection of osteoporosis by dual energy X-ray absorptiometry (DXA) of the calcaneus: is the WHO criterion applicable?
abstract: The study assessed the precision, sensitivity, and specificity of a recently developed peripheral dual-energy X-ray absorptiometry (DXA) scanner, applied to the calcaneus, in the identification of individuals with osteoporosis at axial sites by DXA. Two hundred and two women, aged 55.2 +/- l3.7 years (mean +/- SD), participated in the study. The precisions (coefficient of variation) of measurements in vitro (0.48%) and in vivo (1.40%) were very good. The in vivo precision was independent of the operator, foot size, foot width, weight, height, and body mass index. Calcaneus BMD correlated moderately (r = 0.494-0.690, P <0.001) with axial BMD measurements by DXA. Using the World Health Organization (WHO) criterion for defining osteoporosis (T score ? -2.5) the specificity of the calcaneus to identify patients with osteoporosis at total hip, femoral neck, spine, or any of these axial sites was excellent (97.0%, 97.0%, 96.5%, and 97.1%, respectively); however, the sensitivity was poor (58.8%, 36.4%, 21.8%, and 20.3%, respectively). Therefore, the WHO criterion is not appropriate for DXA calcaneus. Based on femoral neck BMD for detection of osteoporosis, a more appropriate calcaneus T score threshold would be -1.4 by analyses of receiver-operator characteristic curves; this might serve to select those patients who might appropriately be referred for axial DXA.
authors.affiliation: Clinical Radiology, Imaging Science and Biomedical Engineering, The University, Oxford Road, Manchester M13 9PT, UK.
authors.forename: E M B
authors.initials: EM
authors.lastname: Pacheco
authors.forename: E J
authors.initials: EJ
authors.lastname: Harrison
authors.forename: K A
authors.initials: KA
authors.lastname: Ward
authors.forename: M
authors.initials: M
authors.lastname: Lunt
authors.forename: J E
authors.initials: JE
authors.lastname: Adams
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D002111:Calcaneus / Q000000981:diagnostic imaging*; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000145:classification / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014944:World Health Organization