The ADAS-cog and clinically meaningful change in the VISTA clinical trial of galantamine for Alzheimer's disease
A 4-point ADAS-cog change at 6 months is clinically meaningful for groups. Substantial individual misclassification between the ADAS-cog and clinical measures suggests no inherent meaning to a 4-point ADAS-cog change for a given patient. Methods- Secondary analysis of the video imaging synthesis of treating Alzheimer's disease (VISTA) study: a 4-month, multi-centre, parallel-group, double-blind, placebo-controlled, trial of galantamine in 130 mild-moderate Alzheimer's disease patients (4-month open-label follow-up).
- ADAS-cog responses at 6 months were compared with outcomes on three clinical measures: clinician's interview based impression of change-plus caregiver input (CIBIC+), patient/carer-goal attainment scaling (PGAS) and clinician-GAS (CGAS).
Results- Thirty-seven of 99 patients improved by 4 points on the ADAS-cog at 6 months, and 16/99 showed 4-point worsening.
- ADAS-cog change scores correlated notionally to modestly with changes on the CGAS (r = -0.31), the PGAS (r = -0.29) and the CIBIC+ (r = 0.31).
- As a group, patients with ADAS-cog improvement were significantly more likely to improve on the clinical measures; those who worsened showed non-significant clinical decline.
- Individually, about half were misclassified in relation to each clinical measure; often when the ADAS-Cog detected no change, clinically meaningful effects could be detected. Even so, no ADAS-Cog cut-point optimally classified patients' clinical responses.
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