Propriedades do "questionário do informante sobre o declínio cognitivo do idoso" (IQCODE) no rastreio diagnóstico do comprometimento cognitivo leve (CCL) / Diagnostic properties of the Informant Questionnaire of Cognitive Decline in the Elderly in mild cognitive impairment

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Introduction: The Informant Questionnaire of Cognitive Decline in the Elderly is a screening diagnostic instrument which is based on given information from family members and caregivers regarding a possible patients cognitive impairment. Despite its good sensitivity for suspected dementia caseness, few studies have been carried out using the diagnosis properties of the IQCODE to screen for Mild Cognitive Impairment (MCI). MCI corresponds to a condition of a risk factor for dementia outcome and is characterized by the presence of cognitive changes measured objectively, indicating an impairment in comparison with the expected performance for individuals at the same age and years of schooling. These deficits are insufficient for dementia diagnosis in case of preserved global cognitive functioning as well as in the capacity to perform daily activities (Winblad, 2004). Objectives: Examine diagnostic properties of the IQCODE in identifying cut-off scores which best distinguish the cognitively normal elderly from those with MCI; to correlate these results with other widely used cognitive tests, such as the Mini Mental State Examination (MMSE), the Clock Drawing Test (CDT) and the Cambridge Cognitive Test (CAMCOG); to identify among the 26 items in the IQCODE those clusters which best contribute to the identification of the cases. Methods: Cross-sectional study in a sample of 167 elderly subjects (Controls: n=51, MCI: n=58 and Alzheimer Disease (AD): n=58) followed at the Psychogeriatric Clinic of the Laboratory of Neuroscience (LIM-27), Department and Institute of Psychiatry, Faculty of Medicine, University of São Paulo. The cognitive diagnosis was reached by consensus at expert multi-disciplinary meetings (gold standard), taking into account clinical and neuropsychological evaluation. The mean age in each group was respectively: 67.5(±5.6), 70.2 (±6.1) and 75.5 (±8.4) years, and mean of years of schooling were 12.6(±5.4), 9.6(±5.7) and 8.5(±5.5) years. ROC (Receiver Operating Characteristics) Curve analysis were carried out to determine diagnostic accuracy of the IQCODE and the comparative tests in paired sets (MCI versus Controls, MCI versus AD, AD versus Controls); by logistic regression analysis it was evaluated the prediction of MCI and AD with the IQCODE and its combined usage with the comparative tests; finally by cluster analysis it was evaluated the different distribution of the IQCODE items in MCI patients and its subtypes. Results: The IQCODE cut-off scores for diagnostic groups separation were: (a) AD versus Controls: 3.3 (AUC=0.90; sensitivity: 84.5%; specificity: 82.4 %( b) MCI versus Controls: 3.1 (AUC=0.73; sensitivity: 77.6%; specificity%: 60.8); (c) MCI versus AD: 3.4 (AUC=0.81; sensitivity: 79.3%; specificity: 70.7%). The IQCODE had the best correlation with the CAMCOG (=0.542; p<0.001). According to cluster analysis, the episodic memory grouping was the most relevant in identifying amnestic MCI. Conclusions: The IQCODE achieved best results to discriminate cognitively unimpaired elderly from MCI when combined with the CAMCOG. Cluster analysis of the IQCODE better predicts MCI and its subtypes.

ASSUNTO(S)

comprometimento cognitivo leve iqcode diagnosis diagnóstico iqcode mild cognitive impairment

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