P(C) ANALYSIS FACILITATES DEMENTIA DIAGNOSIS

A modified receiver operating characteristic (ROC) analysis technique was applied to a sample of 161 consecutive volunteers seen in a dement ia clinic. Clinical, imaging, neuropsychological, and laboratory evalu ation guided experienced clinicians in clinical diagnosis, taken as th e ''gold standard.'' Two symptom inventories, the Hachinski Ischemic S core and the Dementia of the Alzheimer's Type Inventory, were obtained by clinicians who were blind to final clinical diagnosis; scores on t hese inventories correlate with the likelihoods of multiinfarct dement ia and Alzheimer's disease, respectively. A disjunctive sequential tes ting strategy was analyzed such that subthreshold scores on the first test identified patients for whom the second test was considered. Both tests were analyzed at all possible cutoff-point combinations and in both possible testing sequences. Diagnoses based on these tests were c ompared with the clinical ''gold standard'' diagnoses to determine the accuracy of the testing procedures. The best strategy correctly class ified 154/161 (95.6%) of the dementia patients and required cutoff poi nts (5 for the HIS and 10 for the Dementia of the Alzheimer's Type Inv entory) that were lower than those usually recommended for either test used alone (i.e., 7 and 14, respectively). The Hachinski Ischemic Sco re-then Dementia of the Alzheimer's Type inventory testing sequence wa s superior to the reverse strategy. A sensitivity analysis (varying pr evalences of Alzheimer's disease, multi-infarct dementia, and other de mentias) revealed similar test Performances across a wide range of pre valences. These data suggest. that simple clinical tests that take app roximately 30 minutes to administer can produce diagnostic classificat ions of dementia that are similar to those of clinicians experienced i n dementia diagnosis.