COMBINING COGNITIVE TESTING AND INFORMANT REPORT TO INCREASE ACCURACYIN SCREENING FOR DEMENTIA

Objective: Cognitive testing and an informant report questionnaire wer e combined to determine whether their use in combination could improve accuracy in screening for the diagnosis of dementia over either test used alone. Methods of combining test scores that can be readily appli ed in clinical settings were developed and assessed. Method: The subje cts were 106 patients admitted to the geriatric hospital or outpatient s assessed at the memory clinic of the university hospital system in G eneva, Switzerland. The instruments used were the Mini-Mental State an d the short form of the Informant Questionnaire on Cognitive Decline i n the Elderly. The diagnosis of dementia was made according to DSM-IV criteria. Results: Logistic regression demonstrated that the combinati on of the Mini-Mental State and the Informant Questionnaire on Cogniti ve Decline in the Elderly resulted in more accurate prediction of case ness than either test alone. The performance of logical ''or'' and ''a nd'' combinations of test results and a weighted sum of scores on the two tests as screens for dementia were investigated by using receiver operating characteristic analysis. By using suitable cutoff points, bo th the ''or'' rule and the weighted sum were shown to be capable of im proving performance over that of either test used alone. Conclusions: This study shows that informant report can be formally incorporated in to assessment for dementia in such a way as to increase the accuracy o f detection of cases and noncases. A graphical method was developed th at enables the most robust approach to be applied to individual cases without any calculation.