Validity and reliability of the AD8 informant interview in dementia

Department of Pathology and Immunology, Washington University in St. Louis, San Luis, Missouri, United States
Neurology (Impact Factor: 8.29). 01/2007; 67(11):1942-8. DOI: 10.1212/01.wnl.0000247042.15547.eb
Source: PubMed


To establish the validity, reliability, and discriminative properties of the AD8, a brief informant interview to detect dementia, in a clinic sample.
We evaluated 255 patient-informant dyads. We compared the number of endorsed AD8 items with an independently derived Clinical Dementia Rating (CDR) and with performance on neuropsychological tests. Construct and concurrent validity, test-retest, interrater and intermodal reliability, and internal consistency of the AD8 were determined. Receiver operator characteristic curves were used to assess the discriminative properties of the AD8.
Concurrent validity was strong with AD8 scores correlating with the CDR (r = 0.75, 95% CI 0.63 to 0.88). Construct validity testing showed strong correlation between AD8 scores, CDR domains, and performance on neuropsychological tests. The Cronbach alpha of the AD8 was 0.84 (95% CI 0.80 to 0.87), suggesting excellent internal consistency. The AD8 demonstrated good intrarater reliability and stability (weighted kappa = 0.67, 95% CI 0.59 to 0.75). Both in-person and phone administration showed equal reliability (weighted kappa = 0.65, 95% CI 0.57 to 0.73). Interrater reliability was very good (Intraclass correlation coefficient = 0.80, 95% CI 0.55 to 0.92). The area under the curve was 0.92 (95% CI 0.88 to 0.95), suggesting excellent discrimination between nondemented individuals and those with cognitive impairment regardless of etiology.
The AD8 is a brief, sensitive measure that validly and reliably differentiates between nondemented and demented individuals. It can be used as a general screening device to detect cognitive change regardless of etiology and with different types of informants.

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    • "The administration of the AD8 requires minimal training and can be conducted either in person or over the phone within 3 minutes [13] [14] [15] [16] [17] [18]. The AD8 has been previously validated to identify patients with varying severity of cognitive impairment in epidemiology studies [13] [14] [17] [19] and tertiary clinical settings [15] [16] [18] [20]. It is also well tolerated by the informants and healthcare professionals in primary healthcare settings [21]. "
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    ABSTRACT: The informant AD8 has excellent discriminant ability for dementia case finding in tertiary healthcare settings. However, its clinical utility for dementia case finding at the forefront of dementia management, primary healthcare, is unknown. Therefore, we recruited participants from two primary healthcare centers in Singapore and measured their performance on the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Clinical Dementia Rating (CDR), and a local formal neuropsychological battery, in addition to the AD8. Logistic regression was conducted to examine the associations between demographic factors and dementia. Area under the receiver operating characteristics (ROC) curve analysis was used to establish the optimal cut-off points for dementia case finding. Of the 309 participants recruited, 243 (78.7%) had CDR = 0, 22 (7.1%) CDR = 0.5, and 44 (14.2%) CDR ≥1. Age was strongly associated with dementia, and the optimal age for dementia case finding in primary healthcare settings was ≥75 years. In this age group, the AD8 has excellent dementia case finding capability and was superior to the MMSE and equivalent to the MoCA [AD8 AUC (95% CI): 0.95 (0.91-0.99), cut-off: ≥3, sensitivity: 0.90, specificity: 0.88, PPV: 0.79 and NPV: 0.94; MMSE AUC (95% CI): 0.87 (0.79-0.94), p = 0.04; MoCA AUC (95% CI): 0.88 (0.82-0.95), p = 0.06]. In conclusion, the AD8 is well suited for dementia case finding in primary healthcare settings.
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    • "First, we used the same interviewers to administer the AD8 instrument in all screenings so that we would not have interrater differences with regard to the study results. Second we used the same instrument, AD8, to avoid the biases of different tools used in different screening sites, and since AD8 is capable of screening very mild dementia [8–10], it would be more sensitive as compared to other tools used in the past such as MMSE [2–4]. Third, we surveyed individuals in the northern, central, southern, and eastern parts of Taiwan to reflect the status of screening results for all of Taiwan, which should be more objective when compared to other published studies in limited areas [2–7] in order to more accurately reflect and report on the status of dementia in Taiwan. "
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    • "The Six-Item Cognitive Impairment Test (6CIT), a purely verbal cognitive screening instrument [6], was administered, on which she scored 4/28, a score at the upper limit of the normal range [7]. On the AD8, an informant screening questionnaire for dementia [8], which was completed by a family friend who had known the patient for 3 years, she scored 4/8, above the recommended cutoff for dementia [9]. "
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