title: Evaluating the value of repeat bone mineral density measurement and prediction of fractures in older women: the study of osteoporotic fractures.
abstract: BACKGROUND
  Whether repeat bone mineral density (BMD) measurement adds benefit beyond the initial BMD measurement in predicting fractures in older women is unknown.
  
  
  METHODS
  We prospectively measured total hip BMD in 4124 older women (mean +/- SD age, 72 +/- 4 years) from 1989 to 1990 and again 8 years later. Incident nontraumatic hip and nonspine fractures were validated by radiology reports (>95% follow-up). In addition, spine fractures were defined morphometrically in 2129 of these women by lateral spine x-ray films from 1991 to 1992 and then again 11.4 years later. Prediction of fracture risk was assessed with proportional hazards models and receiver operating characteristic curves for BMD measures.
  
  
  RESULTS
  Over a mean of 5 years after the repeat BMD measure, 877 women experienced an incident nontraumatic nonspine fracture (275 hip fractures). In addition, 340 women developed a spine fracture. After adjustment for age and weight change, initial and repeat BMD measurements were similarly associated with fracture risk (per unit standard deviation lower in BMD) for nonspine (hazard ratio, 1.6), spine (odds ratio, 1.8-1.9), and hip (hazard ratio, 2.0-2.2) fractures (P<.001 for all models). Areas under the receiver operating characteristic curves (AUC) revealed no significant differences to discriminate nonspine (AUC, 0.65), spine (AUC, 0.67-0.68), or hip (AUC, 0.73-0.74) fractures between models with initial BMD, repeat BMD, or initial BMD plus change in BMD. Stratification by initial BMD t scores (normal, osteopenic, or osteoporotic), high bone loss, or hormone therapy did not alter results.
  
  
  CONCLUSIONS
  In healthy, older, postmenopausal women, repeating a measurement of BMD up to 8 years later provides little additional value besides the initial BMD measurement for predicting incident fractures.
authors.affiliation: Center for Health Research, Kaiser Permanente Northwest/Hawaii, Portland, OR 97227, USA. Teresa.Hillier@kp.org
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Hillier
authors.forename: Katie L
authors.initials: KL
authors.lastname: Stone
authors.forename: Doug C
authors.initials: DC
authors.lastname: Bauer
authors.forename: Joanne H
authors.initials: JH
authors.lastname: Rizzo
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Pedula
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Ensrud
authors.forename: Marc C
authors.initials: MC
authors.lastname: Hochberg
authors.forename: Steve R
authors.initials: SR
authors.lastname: Cummings
mesh_terms: D000368:Aged; D019540:Area Under Curve; D015519:Bone Density; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology* / Q000503:physiopathology; D006801:Humans; D016015:Logistic Models; D011446:Prospective Studies; D012372:ROC Curve; D011859:Radiography; D018570:Risk Assessment; D013131:Spine / Q000000981:diagnostic imaging