Efficacy of 13.3 mg/24 h versus 4.6 mg/24 h rivastigmine patch on activities of daily living in severe Alzheimer’s disease

OBJECTIVE Investigate efficacy of 13.3 mg/24 h rivastigmine patch in patients with severe Alzheimer's disease on Alzheimer's Disease Cooperative Study-Activities of Daily Living Scale-Severe Impairment Version items and domains. METHODS Retrospective analysis of the 24-week, randomized, double-blind ACTivities of daily living and cognitION (ACTION) study, using factor analysis to establish "best fit" for Alzheimer's Disease Cooperative Study-Activities of Daily Living Scale-Severe Impairment Version items into domains. Treatment differences (13.3 vs 4.6 mg/24 h patch) on items and domains were assessed. RESULTS Overall, 632 patients provided Alzheimer's Disease Cooperative Study-Activities of Daily Living Scale-Severe Impairment Version data. Factor analysis yielded four domains. The 13.3 versus 4.6 mg/24 h patch demonstrated significantly greater efficacy on "Daily function" (p = 0.038), supported by greatest effect sizes on items within this domain, and trend toward greater efficacy on "Communication" (p = 0.052). No significant between-group differences were observed on "Independence" (p = 0.600) or "Environment" (p = 0.261). CONCLUSION The 13.3 mg/24 h patch was superior to 4.6 mg/24 h patch on "Daily function" in severe Alzheimer's disease.