title: Agreement in cognitive and clinical assessments in Alzheimer's disease.
abstract: OBJECTIVE
  To estimate agreement among scores on three common assessments of cognitive function.
  
  
  METHODS
  Baseline responses on the Alzheimer's Disease Assessment Scale - Cognitive, Clinical Dementia Rating, and the Mini-Mental State Examination were obtained from two clinical trials (n = 138 and n = 351). A graphical method of examining agreement, the means-difference or Bland-Altman plot, was followed by Levene's test of the equality of variance corrected for multiple comparison within each sample.
  
  
  RESULTS
  70-78% of variability was shared by one factor, suggesting that all three instruments reflect cognitive impairment. However, agreement among tests was significantly worse for individuals with greater-than-average, relative to individuals with less-than-average, cognitive impairment.
  
  
  CONCLUSIONS
  Worse agreement between tests, as a function of increasing cognitive impairment, implies that interpretation of these tests and selection of coprimary cognitive impairment outcomes may depend on impairment level.
authors.affiliation: Departments of Neurology, Biostatistics, Bioinformatics and Biomathematics, and Psychiatry, Georgetown University School of Medicine, Washington, D.C. 20057, USA. ret7@georgetown.edu
authors.forename: Rochelle E
authors.initials: RE
authors.lastname: Tractenberg
authors.forename: Paul S
authors.initials: PS
authors.lastname: Aisen
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000523:psychology*; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000188:drug therapy / Q000523:psychology; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011241:Prednisone / Q000627:therapeutic use; D011597:Psychomotor Performance / Q000502:physiology
chemical_list: D000893:Anti-Inflammatory Agents; D011241:Prednisone