A Comparative Evaluation of the KDSQ-C, AD8, and SMCQ as a Cognitive Screening Test to Be Used in National Medical Check-ups in Korea

Abstract

Background Korea has a periodic general health check-up program that uses the Korean Dementia Screening Questionnaire-Cognition (KDSQ-C) as a cognitive dysfunction screening tool. The Alzheimer Disease 8 (AD8) and Subjective Memory Complaints Questionnaire (SMCQ) are also used in clinical practice. We compared the diagnostic ability of these screening questionnaires for cognitive impairment when completed by participants and their caregivers. Hence, we aimed to evaluate whether the SMCQ or AD8 is superior to the KDSQ-C and can be used as its replacement. Methods A total of 420 participants over 65 years and their informants were recruited from 11 hospitals for this study. The patients were grouped into normal cognition, mild cognitive impairment, and dementia subgroups. The KDSQ-C, AD8, and SMCQ were completed separately by participants and their informants. Results A receiver operating characteristic analysis of questionnaire scores completed by participants showed that the areas under the curve (AUCs) for the KDSQ-C, AD8, and SMCQ for diagnosing dementia were 0.75, 0.8, and 0.73, respectively. Regarding informant-completed questionnaires, the AD8 (AUC of 0.93), KDSQ-C (AUC of 0.92), and SMCQ (AUC of 0.92) showed good discriminability for dementia, with no differences in discriminability between the questionnaires. Conclusion When an informant-report is possible, we recommend that the KDSQ-C continues to be used in national medical check-ups as its discriminability for dementia is not different from that of the AD8 or SMCQ. Moreover, consistent data collection using the same questionnaire is important. When an informant is not available, either the KDSQ-C or AD8 may be used. However, in the cases of patient-reports, discriminability is lower than that for informant-completed questionnaires.

Self‐ and informant‐reported cognitive functioning and awareness in subjective cognitive decline, mild cognitive impairment, and very mild Alzheimer disease

“…Both participants and informants separately completed the three questionnaires. Prior study for the comparative evaluation of questionnaires for screening cognitive dysfunction reported that informant‐ and self‐rated questionnaire scores had moderate correlations (Spearman correlation ρ = 0.522‐0.591, P < .001). In addition, correlations among three questionnaire scores were high for both self‐ratings ( ρ = 0.753‐0.804, all P < .001) and informant ratings ( ρ = 0.861‐0.890, P < .001) …”

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

“…Our previous study found that the KDSQ-C had good discriminability for dementia. 2 The original version of the KD-SQ-C includes 15 questions that assess the 3 dimensions of memory impairment (items 1-5), other cognitive impairments including language impairments (items 6-10), and the ability to perform complex tasks in daily life (items 11-15). We divided the original version of the KDSQ-C into four subscales (I, II, III, and IV) and we compared the reliability and validity of each of these four subscales as a screening tool for cognitive dysfunction.…”

“…The detailed baseline demographic characteristics of the study participants were presented in our previous paper. 2 In brief, the sample consisted of 200 subjects with normal cognition, 50 patients with MCI, and 170 patients with dementia (Table 1). The mean age at the time of assessment was older and the educational level was lower in the dementia group than in the normal cognition group.…”

“…1 Our previous study recommended that the KDSQ-C should continue to be used in national medical checkups when an informant report is possible, since its discriminability for dementia does not differ from that of other dementia questionnaires. 2 Moreover, consistent data collection using the same questionnaire is important in a national health checkup system. Therefore, when an informant is not available, the KDSQ-C may be completed by the patient.…”

Effect of Severe External Airborne Agents’ Exposure on Dementia

“…Dementia screening test was evaluated using the KDSQ-C short form that includes five questions assessing memory impairment [ 23 ]. Response options of “never”, “sometimes”, and “frequently” are scored as 0, 1, and 2, respectively, and the cut-off values for dementia was a sum score >4 [ 24 ]. A score >4 in the KDSQ-C was defined as positive in the second NSPTA during the follow-up period.…”