The overall aim of this study was to develop a method of measuring change in cognitive ability from the person's perspective. Cognitive change items came from an item pool that was used to develop the Communicating Cognitive Concerns Questionnaire (C3Q). The change items were administered to a test sample of 211 people with HIV + and a sample of 484 people drawn from the general population (HIV- sample). Rasch analysis was used to identify items that formed a linear continuum and correlations with measures of related constructs were used to support the interpretability of the new measure. Eleven of the original 12 change items fit the unidimensional Rasch model in both samples with a near similar ordering of the items. The average value for cognitive change of the HIV + sample was greater than that of the HIV- sample. Values on C3Q-Change correlated most highly (> 0.7) with current self-reported cognitive status and measures of depression and anxiety (> 0.6). The lowest correlation was with performance-based cognitive ability (r = 0.2). The items of C3Q-Change fit a strong measurement model and related to converging constructs in an expected way. Further work needs to be done to assess the meaning of self-reported cognitive change in relationship to measured change and to examine sources of differential item functioning.
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