Published online Jan 19, 2020. doi: 10.5498/wjp.v10.i1.1
Peer-review started: June 23, 2019
First decision: August 20, 2019
Revised: November 14, 2019
Accepted: November 26, 2019
Article in press: November 26, 2019
Published online: January 19, 2020
Cognitive issues such as Alzheimer’s disease and other dementias confer a substantial negative impact. Problems relating to sensitivity, subjectivity, and inherent bias can limit the usefulness of many traditional methods of assessing cognitive impairment.
To determine cut-off scores for classification of cognitive impairment, and assess Cognivue® safety and efficacy in a large validation study.
Adults (age 55-95 years) at risk for age-related cognitive decline or dementia were invited via posters and email to participate in two cohort studies conducted at various outpatient clinics and assisted- and independent-living facilities. In the cut-off score determination study (n = 92), optimization analyses by positive percent agreement (PPA) and negative percent agreement (NPA), and by accuracy and error bias were conducted. In the clinical validation study (n = 401), regression, rank linear regression, and factor analyses were conducted. Participants in the clinical validation study also completed other neuropsychological tests.
For the cut-off score determination study, 92 participants completed St. Louis University Mental Status (SLUMS, reference standard) and Cognivue® tests. Analyses showed that SLUMS cut-off scores of < 21 (impairment) and > 26 (no impairment) corresponded to Cognivue® scores of 54.5 (NPA = 0.92; PPA = 0.64) and 78.5 (NPA = 0.5; PPA = 0.79), respectively. Therefore, conservatively, Cognivue® scores of 55-64 corresponded to impairment, and 74-79 to no impairment. For the clinical validation study, 401 participants completed ≥ 1 testing session, and 358 completed 2 sessions 1-2 wk apart. Cognivue® classification scores were validated, demonstrating good agreement with SLUMS scores (weighted κ 0.57; 95%CI: 0.50-0.63). Reliability analyses showed similar scores across repeated testing for Cognivue® (R2 = 0.81; r = 0.90) and SLUMS (R2 = 0.67; r = 0.82). Psychometric validity of Cognivue® was demonstrated vs. traditional neuropsychological tests. Scores were most closely correlated with measures of verbal processing, manual dexterity/speed, visual contrast sensitivity, visuospatial/executive function, and speed/sequencing.
Cognivue® scores ≤ 50 avoid misclassification of impairment, and scores ≥ 75 avoid misclassification of unimpairment. The validation study demonstrates good agreement between Cognivue® and SLUMS; superior reliability; and good psychometric validity.
Core tip: This study was designed to address the question of how to identify early cognitive impairment and how to monitor cognitive impairment over time with high reliability. This is critical in patients at risk for age-related cognitive decline. The study results demonstrated that Cognivue - through its unique adaptive psychophysics technology - had good validity and psychometric properties, as well as superior test-retest reliability compared to the St. Louis University Mental Status examination. Therefore, as a quantitative, computerized, assessment tool, Cognivue represents a safe and effective method for clinicians to more conveniently and effectively identify and track cognitive impairment.