title: Rivastigmine in moderately severe-to-severe Alzheimer's disease: Severe Impairment Battery factor analysis.
abstract: BACKGROUND
  The Severe Impairment Battery (SIB) is validated for assessing cognition in patients with severe dementia. The current analysis aimed to further investigate the cognitive efficacy of rivastigmine capsules, as assessed by SIB factor scores, in patients with moderately severe-to-severe Alzheimer's disease (AD).
  
  
  METHODS
  This was a retrospective analysis of a 26-week, multicenter, randomized, double-blind, placebo-controlled study of oral rivastigmine conducted in Spain. Previously reported outcome measures included the full SIB. Current analyses examined calculated scores and effect sizes for the change from baseline at Week 26 on: newly defined SIB subscales (derived by a factor analysis of the 40 SIB items, using the PROC FACTOR function (SAS)); previously defined memory, language and praxis subscales (derived by previous analysis of the nine SIB domains); and the individual SIB items. Treatment differences were assessed.
  
  
  RESULTS
  SIB data were provided by 104 rivastigmine-treated patients and 106 patients receiving placebo (Intent-To-Treat Last Observation Carried Forward population). Significantly less decline was observed on the previously defined memory and language subscales, and the newly defined working memory/memory subscale in rivastigmine-treated patients (all P < 0.05 versus placebo). Calculation of effect sizes demonstrated numerically greater efficacy of rivastigmine versus placebo on each of the subscales, and a broad range of SIB items; greatest effect sizes were observed on SIB items assessing the current month (effect size = 0.30) and digit span series (effect size = 0.33).
  
  
  CONCLUSIONS
  These data suggest the observed efficacy of rivastigmine in moderately severe-to-severe AD is likely a cumulative effect across a range of tasks. Rivastigmine demonstrates broad cognitive efficacy in this patient population.
authors.affiliation: Alzheimer's Disease Center, Comprehensive Center on Brain Aging, NYU Langone Medical Center, Room 506, 145 East 32nd Street, New York, NY 10016, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Ferris
authors.affiliation: Alzheimer's Disease Center, Comprehensive Center on Brain Aging, NYU Langone Medical Center, Room 506, 145 East 32nd Street, New York, NY 10016, USA.
authors.forename: Stella
authors.initials: S
authors.lastname: Karantzoulis
authors.affiliation: Novartis Pharmaceuticals Corporation, East Hanover, NJ 07936-1080, USA.
authors.forename: Monique
authors.initials: M
authors.lastname: Somogyi
authors.affiliation: Novartis Pharmaceuticals Corporation, East Hanover, NJ 07936-1080, USA.
authors.forename: Xiangyi
authors.initials: X
authors.lastname: Meng