Clinical meaningfulness of Alzheimer's Disease Assessment Scale-Cognitive subscale change in relation to goal attainment in patients on cholinesterase inhibitors.

INTRODUCTION: The clinical meaningfulness of Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) subscale change is disputed. We compared 2- to 4-point ADAS-Cog changes with changes in Goal Attainment Scaling (GAS) and everyday function across initial ADAS-Cog scores and treatment responses.

METHODS: This exploratory analysis evaluated mild-moderate Alzheimer's disease patients treated with donepezil (12 months) or galantamine (8 months). Clinical meaningfulness was defined as concomitant ADAS-Cog and GAS changes of ±3 points and/or functional improvement.

RESULTS: Patients with ≥3-point ADAS-Cog improvement significantly improved on GAS but not on standard tests of everyday function. ADAS-Cog "no change" (≤±3 points) was seen with mean GAS improvement. Initial ADAS-Cog improvement made endpoint improvement (ADAS-Cog 3 points and GAS 1 point) more likely (odds ratio = 6.9; 95% confidence interval = 2.5-19.5). In contrast, initial deterioration made endpoint improvement unlikely (0.33; 0.14-0.64).

DISCUSSION: ADAS-Cog improvement and no change were each associated with GAS improvement. Initial ADAS-Cog worsening was unlikely to result in later improvement.

CLINICAL TRIAL REGISTRATION NUMBER: ISRCTN26167328.