Mixed-model analysis of incomplete longitudinal data from a high-dose trial of tacrine (Cognex) in Alzheimer's patients.
Mixed-model techniques are applied to incomplete longitudinal data from a double-blind, placebo-controlled, parallel-group, high-dose study of tacrine in patients with Alzheimer's disease. The study consisted of a 30-week double-blind treatment period. Patients were randomized to one of four treatment groups. Dosing was initiated at 40 mg/day and increased in increments of 40 mg/day every 6 weeks until the target dose was achieved. If the study medication was not well tolerated or there were significant elevations in alanine aminotransferase, patients were withdrawn from the study. The use of SAS procedure PROC MIXED for the analysis of incomplete longitudinal data is discussed. This approach is used to evaluate disease progression over time and the effect of incremental dose increases of tacrine on changes on the Alzheimer's Disease Assessment Scale-Cognitive subscale.
Smith
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Biometrics Department, Parke-Davis Pharmaceutical Research, Ann Arbor, Michigan 48105, USA.
D000368:Aged; D000544:Alzheimer Disease / Q000188:drug therapy*; D000704:Analysis of Variance; D018450:Disease Progression; D004311:Double-Blind Method; D006801:Humans; D008137:Longitudinal Studies; D015233:Models, Statistical; D018697:Nootropic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D010352:Patient Dropouts / Q000706:statistics & numerical data; D012107:Research Design; D013619:Tacrine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
D018697:Nootropic Agents; D013619:Tacrine