Reliability and Validity of a Short Form of the Korean Dementia Screening Questionnaire-Cognition

BACKGROUND AND PURPOSE: We aimed to determine the reliability and validity of a short form of the Korean Dementia Screening Questionnaire-Cognition (KDSQ-C) as a screening tool for cognitive dysfunction. METHODS: This study recruited 420 patients older than 65 years and their informants from 11 hospitals, and categorized the patients into normal cognition, mild cognitive impairment, and dementia subgroups. The KDSQ-C was completed separately by the patients and their informants. We abstracted three components of the KDSQ-C and combined these components into the following four subscales: KDSQ-C-I (items 1–5, memory domain), KDSQ-C-II (items 1–5 & 11–15, memory domain+activities of daily living), KDSQ-C-III (items 1–5 & 6–10, memory domain+other cognitive domains), and KDSQ-C-IV (items 6–10 & 11–15, other cognitive domains+activities of daily living). The reliability and validity were compared between these four subscales. RESULTS: A receiver operating characteristic (ROC) analysis of questionnaire scores provided by the patients showed that the areas under the ROC curves (AUCs) for the KDSQ-C, KDSQC-I, and KDSQ-C-II for diagnosing dementia were 0.75, 0.72, and 0.76, respectively; the corresponding AUCs for informant-completed questionnaires were 0.92, 0.89, and 0.92, indicating good discriminability for dementia. CONCLUSIONS: A short form of the patient- and informant-rated versions of the KDSQ-C (KDSQ-C-II) is as capable as the 15-item KDSQ-C in screening for dementia.