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Validation of a French Version of an Informant-Based Questionnaire as a Screening Test for Alzheimer's Disease

Published online by Cambridge University Press:  02 January 2018

Samuel Law
Affiliation:
Department of Medicine
Christina Wolfson*
Affiliation:
Department of Epidemiology & Biostatistics, McGill University, Montréal, Canada H3T 1E2
*
Dr Wolfson, Centre for Clinical Epidemiology and Community Studies, Rm A 127, Sir Mortimer B. Davis Jewish General Hospital, 3755, Chemin de la Côte Ste-Catherine, Montréal, Quebec, Canada H3T 1E2

Abstract

Background

Development of informant-based screening tests for dementia is an emerging field. The reliability and validity of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), an instrument that screens for dementia in general, have been established. We conducted a study to validate a French version of the IQCODE as a screening test for Alzheimer's dementia in the elderly living in the community.

Method

In the Canadian Study of Health and Aging, subjects were screened in their own homes using the Modified Mini-Mental State Exam (3-MS). Those who screened positive, along with a sample of subjects who screened negative, were referred for a complete clinical examination. In Quebec, an informant was asked to complete the French version, IQCODE (F), at that time. Based on the final clinical diagnoses, performances of the IQCODE (F) and Mini-Mental State Examination (MMSE, converted from 3-MS) in screening for Alzheimer's disease were evaluated.

Results

Of the 237 subjects, the mean IQCODE (F) score was 3.4 (s.d. = 0.6), on a 5-point scale (1 = improvement in condition over the past 10 years, 5 = marked deterioration, 3 = no change). The mean MMSE score was 23.1 (s.d. = 4.5). The scores on the two scales were correlated (r = –0.44, P < 0.001). The IQCODE (F) scores were unrelated to education (r = –0.07, P > 0.3) in contrast to the MMSE scores (r = 0.28, P < 0.001). With respect to a diagnosis of probable Alzheimer's disease, the IQCODE (F) (cut-off point 3.6) had a sensitivity of 75% and a specificity of 95.6%. The sensitivity and specificity of the MMSE (cut-off point 23) were 70% and 82.3% respectively.

Conclusion

The findings of the IQCODE (F) are consistent with those of the English version in correlation with the MMSE and apparent freedom from educational bias. The IQCODE is superior to the MMSE as a screening test for probable Alzheimer's disease in the elderly living in the community. It may be a useful addition to the screening tests already available, especially for the less well educated.

Type
Papers
Copyright
Copyright © 1995 The Royal College of Psychiatrists 

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