Evaluating the Accuracy of Web-Based and In-Clinic Subjective Cognitive Decline Assessments in Detecting Cognitive Impairment: Multicohort Study.

Background: Scalable tools to efficiently identify individuals likely to have cognitive impairment (CI) are critical in the Alzheimer disease and related dementias field. The Everyday Cognition scale (ECog) and its short form (ECog12) assess subjective cognitive and functional changes and are useful in predicting CI. Recent advances in online technology have enabled the use of web-based cognitive tests and questionnaires to identify CI with greater convenience and scalability. While the effectiveness of the ECog has been demonstrated in clinical settings, its potential to detect CI in remote, unsupervised formats remains underexplored. Objective: This study aimed to compare the ability of the web-based ECog and the in-clinic ECog in distinguishing between individuals with CI and those who are cognitively unimpaired (CU), and to evaluate the effectiveness of the ECog12-the short version of the ECog-compared to the full-length ECog in a web-based setting. Methods: Participants were recruited from the Brain Health Registry (BHR; web-based) and Alzheimer's Disease Neuroimaging Initiative (ADNI; in-clinic) settings with available clinical diagnoses. The ability of the self-reported ECog (Self-ECog), study partner-reported ECog (SP-ECog), Self-ECog12, and SP-ECog12 to discriminate individuals with CI from CU was assessed using receiver operating characteristic (ROC) curves. Area under the ROC curves (AUCs) between BHR and ADNI were compared using the DeLong test, as were AUCs between ECog12 and ECog in BHR. Results: Web-based Self-ECog and SP-ECog scores effectively discriminated CI from CU with AUCs of 0.722 and 0.818, respectively. Similarly, the abbreviated web-based versions, Self-ECog12 and SP-ECog12, also demonstrated discriminative ability (AUC=0.709 and 0.777, respectively). When compared to in-clinic ECog scores, there were no significant differences in the ability to distinguish CI from CU between web-based and in-clinic versions (BHR Self-ECog AUC=0.722 vs ADNI Self-ECog AUC=0.769, DeLong P=.06; BHR SP-ECog AUC=0.818 vs ADNI SP-ECog AUC=0.840, DeLong P=.50). Additionally, the comparison between web-based ECog and ECog12 showed no significant difference in AUCs (BHR Self-ECog AUC=0.722 vs BHR Self-ECog12 AUC=0.709, DeLong P=.18). Conclusions: Web-based ECog scores, both the full-length and short-form, were as valid as in-clinic ECog scores for identifying clinically diagnosed CI. In addition, Self-ECog12 was as effective as full-length Self-ECog to identify CI in a web-based setting, offering a cost-effective and accessible screening tool for large-scale studies. These results highlight the value of the web-based ECog as a valid tool for identifying older adults with CI in a remote clinical study, facilitating early detection and referral for comprehensive evaluations for identifying potential candidates for disease-modifying therapy.