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The clinical meaningfulness of ADAS-Cog changes in Alzheimer's disease patients treated with donepezil in an open-label trial

Kenneth Rockwood1*, Sherri Fay1, Mary Gorman12, Daniel Carver1 and Janice E Graham3

Author affiliations

1 Division of Geriatric Medicine, Department of Medicine, Dalhousie University, Halifax, Canada

2 St. Martha's Regional Hospital, Antigonish, Canada

3 Department of Bioethics, Faculty of Medicine, Dalhousie University, Halifax, Canada

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Citation and License

BMC Neurology 2007, 7:26  doi:10.1186/1471-2377-7-26

Published: 30 August 2007

Abstract

Background

In 6-month anti-dementia drug trials, a 4-point change in the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) is held to be clinically important. We examined how this change compared with measures of clinical meaningfulness.

Methods

This is a secondary analysis of a 12 month open-label study of 100 patients (71 women) diagnosed with mild to moderate AD treated with 5–10 mg of donepezil daily. We studied the observed case, 6-month change from baseline on the ADAS-Cog, the Clinician's Interview Based Impression of Change-Plus Caregiver Input (CIBIC-Plus), patient-Goal Attainment Scaling (PGAS) and clinician-GAS (CGAS).

Results

At 6 months, donepezil-treated patients (n = 95) were more likely to show no change (+/- 3 points) on the ADAS-Cog (56%) than to improve (20%) or decline (24%) by 4-points. ADAS-Cog change scores were little correlated with other measures: from -0.09 for PGAS to 0.27 for the CIBIC-Plus. While patients who improved on the ADAS-Cog were less likely to decline on the clinical measures (26%), 43% of patients who declined on the ADAS-Cog improved on at least two of the clinical measures.

Conclusion

The ADAS-Cog did not capture all clinically important effects. In general, ADAS-Cog improvement indicates clinical improvement, whereas many people with ADAS-Cog decline do not show clinical decline. The open-label design of this study does not allow us to know whether this is a treatment effect, which requires further investigation.