Development of a method for quantifying cognitive ability in the elderly through adaptive test administration

The field of geriatric medicine has identified a need for an evaluative tool that can rapidly quantify global cognitive ability and accurately monitor change over time in patients with a wide range of impairments. We hypothesized that the development of an adaptive test approach to cognitive measurement would help to meet that need. This study aimed to provide evidence for the interpretability of scores obtained from a novel, adaptive approach to cognitive assessment, called the Geriatric Rapid Adaptive Cognitive Estimate (GRACE) method.

An adaptive method for cognitive assessment was developed using data from 185 patients referred for geriatric cognitive assessment, and pilot tested in an additional 137 patients. Correlations between test scores and between rank orders of patients were computed to examine the reliability and validity of cognitive ability scores obtained by (1) administering test questions out of their usual order, (2) administering only a subset of questions, and (3) administering questions adaptively using simplified selection rules based on the most difficult question passed.

Cognitive ability scores obtained with the GRACE method correlated highly with the Montreal Cognitive Assessment (MoCA) scores (r = 0.93) and ranked patients similarly in order of ability (r > 0.87). A simplified adaptive testing algorithm for pencil-and-paper assessment demonstrated moderately high correlations with scores obtained from administering the full set of MMSE and MoCA items as well as the MoCA items alone.

Scores from the GRACE method can be obtained easily in 5-10 minutes, reducing test burden. The resulting numeric score quantifies cognitive ability, allowing clinicians to compare patients and monitor change in global cognition over time. The adaptive nature of this method allows for evaluation of persons across a broader range of cognitive ability levels than currently available tests.