title: Rate of decline in Alzheimer disease measured by a Dementia Severity Rating Scale.
abstract: OBJECTIVE
  To measure clinically relevant change in Alzheimer disease (AD) using a family member-completed Dementia Severity Rating Scale (DSRS) questionnaire.
  
  
  BACKGROUND
  Measuring rate of change provides important clinical information. Most neuropsychologic scores change nonlinearly, complicating their use as a predictor of change throughout the illness.
  
  
  METHODS
  DSRS and Mini Mental State scores were prospectively collected on 702 patients with AD from first evaluation until they became too impaired to return to clinic.
  
  
  RESULTS
  DSRS score increased an average of 4.48 points/y [95% confidence interval (CI): 4.14-4.82] throughout the entire range of severity. In contrast, the Mini Mental State declined an average of 2.15 points/y (95% CI: 1.85-2.46) during the first 2 years, accelerated to 3.83 points/y (95% CI: 3.28-4.38) during the subsequent 3 years, and then slowed to an annual decline of 1.63 points during the last 2 years (95% CI: 0.21-3.05). A younger age of symptom onset was associated with an increased rate of DSRS change (P=0.03).
  
  
  CONCLUSIONS
  The DSRS provides a clinical measure of functional impairment in AD that increases about 4.48 points/y from the earliest symptomatic stage until patients become too severely impaired to return to clinic.
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, 423 Guardian Drive, Philadelphia, PA 19104-6021, USA. sxie@cceb.med.upenn.edu
authors.forename: Sharon X
authors.initials: SX
authors.lastname: Xie
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Ewbank
authors.forename: Jesse
authors.initials: J
authors.lastname: Chittams
authors.forename: Jason H T
authors.initials: JH
authors.lastname: Karlawish
authors.forename: Steven E
authors.initials: SE
authors.lastname: Arnold
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Clark
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires