Diagnostic Accuracy of the Alzheimer's Questionnaire
Background: accurately identifying individuals with cognitive impairment is difficult. Given the time constraints that many clinicians face, assessment of cognitive status is often not undertaken. The intent of this study is to determine the diagnostic accuracy of the Alzheimer's questionnaire (AQ) in identifying individuals with mild cognitive impairment (MCI) and AD.
Methods: utilising a case–control design, 300 [100 AD, 100 MCI, 100 cognitively normal (CN)] older adults between the ages of 53 and 93 from a neurology practice and a brain donation programme had the AQ administered to an informant. Diagnostic accuracy was assessed through receiver-operating characteristic analysis, which yielded sensitivity, specificity and area under the curve (AUC).
Results: the AQ demonstrated high sensitivity and specificity for detecting MCI [89.00 (81.20–94.40)]; [91.00 (83.60–65.80)] and AD [99.00 (94.60–100.00)]; [96.00 (90.10–98.90)]. AUC values also indicated high diagnostic accuracy for both MCI [0.95 (0.91–0.97)] and AD [0.99 (0.96–1.00)]. Internal consistency of the AQ was also high (Cronbach's alpha = 0.89).
Conclusion: the AQ is a valid informant-based instrument for identifying cognitive impairment, which could be easily implemented in a clinician's practice. It has high sensitivity and specificity in detecting both MCI and AD and allows clinicians to quickly and accurately assess individuals with reported cognitive problems.
Given the expected increase in Alzheimer's disease (AD) prevalence in the USA many clinicians will be faced with the prospect of evaluating many individuals for possible cognitive impairment. This problem may be further compounded by the possibility that screening for cognitive impairment may become mandatory under proposed healthcare reform. Often, the first clinician a patient may see is a primary care physician who often has a limited amount of time to assess the individual. In addition to time constraints, many physicians do not screen for cognitive problems unless they receive complaints from patients or patients' families. As a result dementia is not recognised by physicians until it is moderately advanced. Providers also cite a lack of confidence in diagnosing AD as a reason that nearly half of AD patients remain undiagnosed.
This necessitates the use of a brief and accurate screening instrument in order to determine, which patients require further assessment. The most common tool used to screen for dementia is the Mini-Mental Status Examination (MMSE); however, its scores can be biased by education level which can lead to false positive indications of impairment for individuals with low educational attainment and false negative indications of no impairment for highly educated individuals. Informant-based questionnaires, such as the AD8, IQCODE and the DQ, have been developed in order to quickly and accurately identify clinical AD and have demonstrated good sensitivity and specificity (please see Supplementary data available in Age and Ageing online, Table S3>). Although the Clinical Dementia Rating (CDR) is widely used in clinical research settings, its utility in clinical practice is questionable given the length of time necessary for administration.
The Alzheimer's questionnaire (AQ) was designed to be a brief and easily administered assessment for use with collateral sources. A recent pilot study of the AQ demonstrated high sensitivity and specificity for detecting mild cognitive impairment (MCI) and clinical AD. The intent of the current study is to validate the AQ as an accurate informant-based instrument in detecting both MCI and clinical AD.
Abstract and Introduction
Abstract
Background: accurately identifying individuals with cognitive impairment is difficult. Given the time constraints that many clinicians face, assessment of cognitive status is often not undertaken. The intent of this study is to determine the diagnostic accuracy of the Alzheimer's questionnaire (AQ) in identifying individuals with mild cognitive impairment (MCI) and AD.
Methods: utilising a case–control design, 300 [100 AD, 100 MCI, 100 cognitively normal (CN)] older adults between the ages of 53 and 93 from a neurology practice and a brain donation programme had the AQ administered to an informant. Diagnostic accuracy was assessed through receiver-operating characteristic analysis, which yielded sensitivity, specificity and area under the curve (AUC).
Results: the AQ demonstrated high sensitivity and specificity for detecting MCI [89.00 (81.20–94.40)]; [91.00 (83.60–65.80)] and AD [99.00 (94.60–100.00)]; [96.00 (90.10–98.90)]. AUC values also indicated high diagnostic accuracy for both MCI [0.95 (0.91–0.97)] and AD [0.99 (0.96–1.00)]. Internal consistency of the AQ was also high (Cronbach's alpha = 0.89).
Conclusion: the AQ is a valid informant-based instrument for identifying cognitive impairment, which could be easily implemented in a clinician's practice. It has high sensitivity and specificity in detecting both MCI and AD and allows clinicians to quickly and accurately assess individuals with reported cognitive problems.
Introduction
Given the expected increase in Alzheimer's disease (AD) prevalence in the USA many clinicians will be faced with the prospect of evaluating many individuals for possible cognitive impairment. This problem may be further compounded by the possibility that screening for cognitive impairment may become mandatory under proposed healthcare reform. Often, the first clinician a patient may see is a primary care physician who often has a limited amount of time to assess the individual. In addition to time constraints, many physicians do not screen for cognitive problems unless they receive complaints from patients or patients' families. As a result dementia is not recognised by physicians until it is moderately advanced. Providers also cite a lack of confidence in diagnosing AD as a reason that nearly half of AD patients remain undiagnosed.
This necessitates the use of a brief and accurate screening instrument in order to determine, which patients require further assessment. The most common tool used to screen for dementia is the Mini-Mental Status Examination (MMSE); however, its scores can be biased by education level which can lead to false positive indications of impairment for individuals with low educational attainment and false negative indications of no impairment for highly educated individuals. Informant-based questionnaires, such as the AD8, IQCODE and the DQ, have been developed in order to quickly and accurately identify clinical AD and have demonstrated good sensitivity and specificity (please see Supplementary data available in Age and Ageing online, Table S3>). Although the Clinical Dementia Rating (CDR) is widely used in clinical research settings, its utility in clinical practice is questionable given the length of time necessary for administration.
The Alzheimer's questionnaire (AQ) was designed to be a brief and easily administered assessment for use with collateral sources. A recent pilot study of the AQ demonstrated high sensitivity and specificity for detecting mild cognitive impairment (MCI) and clinical AD. The intent of the current study is to validate the AQ as an accurate informant-based instrument in detecting both MCI and clinical AD.
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