Interpreting Addenbrooke's Cognitive Examination-III Scores in Dementia: Performance Distributions and Clinically Meaningful Change

Abstract

Background: The Addenbrooke's Cognitive Examination-III (ACE-III) is a common cognitive screening measure. We provide performance deciles, descriptive performance bands and indices of reliable change between repeat assessments using the ACE-III in a large cohort of dementia participants and healthy controls. Methods: Baseline data from 727 participants diagnosed with a dementia syndrome and 157 healthy controls were used to calculate performance deciles and descriptive bands. A subset of 393 participants diagnosed with a dementia syndrome completed two annual assessments. These data were used to calculate 95% confidence intervals of characteristic yearly change in each dementia syndrome. Data from a subset of 74 healthy participants who completed two assessments were used to calculate reliable change indices. Results: Baseline performance was grouped into five descriptive performance bands across the entire spectrum of scores: Very Mild, Mild, Moderate, Severe and Very Severe. Deciles and performance bands are provided for all dementia participants combined, for each syndrome where n > 50, and for healthy controls, stratified by group, sex and years of education. A decline of −7 to −9 points yearly was characteristic for the dementia population, and this varied between syndromes. Reliable change calculations indicate that a 5-point decline from within the ‘normal’ range (88–100) is the minimum clinically important decline on the ACE-III. Conclusions: This study presents a suite of reference data on the ACE-III in a range of dementia syndromes, providing important insight and support to clinicians who work with people living with cognitive impairments.