DIFFERENTIAL-DIAGNOSIS OF DEMENTIA - A PROSPECTIVE EVALUATION OF THE DAT INVENTORY

Objective: To compare prospectively the concordance between the diagno sis of dementia based on clinical criteria and using the DAT Inventory . Design, Setting, and Participants: A prospective study of 81 consecu tive patients referred to a Memory Clinic. Only patients for whom a de finitive diagnosis of dementia was established after 8 to 20 months fo llow-up were retained in the study (n = 76). Measurements: The sensiti vity, specificity, positive and negative predictive values, and overal l diagnostic accuracy of the DAT Inventory were calculated. Kappa valu es were also computed. Results: Based on all patients (n = 76), sensit ivity and specificity were 71% and 95%, respectively, with 98% positiv e prediction, 56% negative prediction, 78% overall accuracy, and kappa of 0.54. Of 21 cases not meeting NINCDS/ADRDA criteria for DAT, one p atient with multi-infarct dementia was misclassified as DAT on the DAT Inventory. Of 55 DAT cases (NINCDS/ADRDA criteria), 16 patients, pred ominantly very mild or mixed cases, were classified as non-DAT on the DAT Inventory. When mixed, very mild, and borderline cases were exclud ed (screening n = 54), DAT Inventory sensitivity increased to 94%, and specificity remained unchanged at 95%, with 97% positive and 91% nega tive prediction, 94% overall accuracy, and kappa of 0.88. Conclusions: In general, scores above the designated cutoff point (>14/20) on the DAT Inventory are consistent with a dinical diagnosis of DAT (NINCDS/A DRDA criteria). Concordance is best in cases of mild to moderate demen tia (Clinical Dementia Rating 1-2). The Inventory is less discriminati ng as a differential diagnostic instrument in cases of very mild demen tia, atypical presentations of DAT, or in cases of mixed pathology.