Application of a Spanish version of the "Informant Questionnaire on Cognitive Decline in the Elderly" in the clinical assessment of dementia

Abstract

We studied the validity of a complete (S-IQCODE) and a shortened (SS- IQCODE) Spanish version of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) for the diagnosis of dementia in a clinical setting. Fifty-three consecutive outpatients were assessed with an extensive workup and followed up for 6 months in a specialized clinic for the diagnosis and management of dementia. Thirty eight (71%) were finally diagnosed as demented. The Mini-Mental State Examination (MMSE) had a slightly greater diagnostic power than did the S-IQCODE and the SS-IQCODE (sensitivity 89% vs. 84% and 79%; specificity 80% vs. 73% for both; positive predictive value 92% vs. 89% and 88%; negative predictive value 75% vs. 65% and 58%), but without statistical significance. Both the S-IQCODE and SS-IQCODE were independent of previous education of the patients. The best diagnostic results were obtained when the cognitive scores of the patient in the MMSE and the report of the relative in the S-IQCODE were simultaneously considered. We conclude that the IQCODE, in a complete as well as in a shortened form, is a good diagnostic instrument in the clinical setting that can enhance the validity of other cognitive tests.