Informant-based screening tools for dementia: an overview of systematic reviews

Abstract

Background Informant-based questionnaires may have utility for cognitive impairment or dementia screening. Reviews describing the accuracy of respective questionnaires are available, but their focus on individual questionnaires precludes comparisons across tools. We conducted an overview of systematic reviews to assess the comparative accuracy of informant questionnaires and identify areas where evidence is lacking. Methods We searched six databases to identify systematic reviews describing diagnostic test accuracy of informant questionnaires for cognitive impairment or dementia. We pooled sensitivity and specificity data for each questionnaire and used network approaches to compare accuracy estimates across the differing tests. We used grading of recommendations, assessment, development and evaluation (GRADE) to evaluate the overall certainty of evidence. Finally, we created an evidence ‘heat-map’, describing the availability of accurate data for individual tests in different populations and settings. Results We identified 25 reviews, consisting of 93 studies and 13 informant questionnaires. Pooled analysis (37 studies; 11 052 participants) ranked the eight-item interview to ascertain dementia (AD8) highest for sensitivity [90%; 95% credible intervals (CrI) = 82–95; ‘best-test’ probability = 36]; while the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) was most specific (81%; 95% CrI = 66–90; ‘best-test’ probability = 29%). GRADE-based evaluation of evidence suggested certainty was ‘low’ overall. Our heat-map indicated that only AD8 and IQCODE have been extensively evaluated and most studies have been in the secondary care settings. Conclusions AD8 and IQCODE appear to be valid questionnaires for cognitive impairment or dementia assessment. Other available informant-based cognitive screening questionnaires lack evidence to justify their use at present. Evidence on the accuracy of available tools in primary care settings and with specific populations is required.

Comparative validity of informant tools for assessing pre‐stroke cognitive impairment

“…As stroke survivors may be too unwell to participate in testing or lack insight into their impairments, ascertainment of premorbid conditions in acute stroke usually requires an interview with the patient's close relative or friend i.e., an informant. The Informant Questionnaire for Cognitive Decline in the Elderly (IQCODE) and Ascertain Dementia 8 (AD8) are the most widely used informant‐based cognitive assessment questionnaires 4 and are used in stroke research and practice. However, at present there is a lack of evidence regarding each tools' validity in stroke and few studies that compare the tests.…”

Informant Accuracy of IQCODE, AD8 and GPCOGi for diagnosis of dementia: Does your friend know best?

“…We used a threshold of > 3.3 as a threshold for an abnormal index test on IQCODE (mean scores range 1-5; higher scores indicating worse cognition). This re ected the threshold used for the pooled analysis in Cochrane systematic review [11]. A threshold of greater or equal to 2 on AD8 (scores range 0-8; higher scores indicating worse cognition ) and < 5 on the GPCOGi (max score 6, lower scores indicating worse cognition).…”

“…A recent overview of informant questionnaires for dementia concluded there is currently only su cient evidence to justify the use of IQCODE and AD8. However, it also highlighted that there is little evidence available for their use in primary care settings despite test performance varying by setting and primary care being an important setting for identifying cognitive impairment [11].…”

The dementia severity rating scale: A potential community screening tool for dementia in low- and middle-income countries

“…However, using cognitive measures alone can be problematic. Many cognitive tasks capture a cross-sectional snapshot of cognitive impairment, rather than the deterioration of cognition necessary in dementia ( Taylor-Rowan et al, 2021 ). These cognitive measures can also be time-consuming, not education-fair, not culturally-fair, and may need well-trained interviewers to ensure standardized and reliable outcomes ( Baldo et al, 2013 ; Li et al, 2012 ; Nasreddine et al, 2004 ; Turana & Handajani, 2011 ).…”

“…Within the dementia literature there are informant-based tools that capture impairment associated with dementia, though their scope and validity, especially cross-culturally, is variable. A recent systematic review of the literature identified that the eight-item interview to ascertain dementia (AD8) and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) have the best screening properties against clinical diagnostic criteria ( Taylor-Rowan et al, 2021 ). Using such instruments requires vigilance about other sources of bias that might be introduced by adopting an informant report.…”