Ecological, convergent, and discriminative validities of the cognitive abilities screening instrument in people with dementia

Abstract

Background: The Cognitive Abilities Screening Instrument (CASI) assesses global cognitive function in people with dementia with 9 domains (i.e., long-term memory, short-term memory, concentration, orientation, attention, abstraction and judgment, language abilities, visual construction, and category fluency). However, the ecological, convergent, and discriminant validities of the CASI have not yet been examined.

Purpose: This study designed to investigate these 3 validities of the CASI in people with dementia.

Methods: Fifty-eight participants underwent assessments with the CASI, 3 functional measures, and 3 cognitive measures. Pearson's r was used to estimate correlations among the CASI and 3 functional measures for examining ecological validity. We computed correlations (r) among the CASI and 3 functional measures for examining convergent validity. An independent t-test was applied to compare the levels of disability, and ceiling/floor effects were analyzed for examining discriminative validity.

Results: The CASI total score and domains had moderate to high correlations with 3 functional measures (r = 0.42-0.80), except in 2 CASI domains (i.e., attention and language). The CASI total score and domains showed moderate to high correlations with 3 cognitive measures (r = 0.45-0.93). The t-test results revealed significant differences (P < .05) in the CASI total score and other domains except for the short-term memory domains. Four domains of the CASI showed noticeable ceiling effects (22.4-39.7%).

Conclusions: The CASI has adequate ecological validity, good convergent validity, and acceptable discriminative validity in people with dementia. The 5 domains with nonsignificant differences or ceiling effects should only be used with caution to distinguish people with dementia.