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Keywords:

  • Alzheimer's disease;
  • cognitive function;
  • rivastigmine;
  • clinical trial

Abstract

Objective

Rivastigmine displays dose-dependent efficacy on cognition in patients with Alzheimer's disease (AD), as measured by the Alzheimer's Disease Assessment Scale–cognitive subscale (ADAS-cog). Subanalysis of the OPTIMA (OPtimising Transdermal Exelon In Mild-to-moderate Alzheimer's disease) study aimed to define ADAS-cog domains by factor analysis of individual items. Efficacy of 13.3 mg/24 h versus 9.5 mg/24 h rivastigmine patch on individual items and newly derived domains was assessed.

Methods

OPTIMA was a 48-week, double-blind (DB) study in patients with mild-to-moderate AD. Patients meeting pre-defined decline criteria during open-label treatment with 9.5 mg/24 h patch were randomized in the DB phase to 13.3 mg/24 h (n = 280) or 9.5 mg/24 h (n = 287) patch. ADAS-cog change from baseline was a co-primary outcome measure. Factor analysis categorized ADAS-cog items into newly derived domains. Change from DB-baseline was calculated for domains and individual items.

Results

Numerically, less decline was displayed with 13.3 mg/24 h versus 9.5 mg/24 h patch in the total ADAS-cog score at all time points (significant at Week 24, p = 0.027). Factor analysis identified two domains: memory and language. Significantly, less decline was observed on the memory domain with 13.3 mg/24 h versus 9.5 mg/24 h patch at Weeks 12, 24, and 48 (p < 0.05; observed cases). Three items (following commands, orientation, and word recognition) displayed numerically less decline with 13.3 mg/24 h versus 9.5 mg/24 h patch at all time points. No significant between-group differences were observed on the language domain.

Conclusion

Results suggest that the greater cognitive efficacy of 13.3 mg/24 h versus 9.5 mg/24 h rivastigmine patch is driven primarily by effects on memory, particularly in the areas of following commands, orientation, and word recognition. Copyright © 2014 John Wiley & Sons, Ltd.