New DSM-V Neurocognitive Disorders Criteria and Their Impact on Diagnostic Classifications of Mild Cognitive Impairment and Dementia in a Memory Clinic Setting

Objective: To examine diagnostic agreement between Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) Neurocognitive Disorders (NCDs) criteria and DSM, Fourth Edition (DSM-IV) criteria for dementia and International Working Group (TWG) criteria for mild cognitive impairment (MCI) and DSM-V's impact on diagnostic classifications of NCDs. The authors further examined clinical factors for discrepancy in diagnostic classifications between the different operational definitions. Methods: Using a cross-sectional study in tertiary memory clinic, the authors studied consecutive new patients aged 55 years or older who presented with cognitive symptoms. Dementia severity was scored based on the Clinical Dementia Rating scale (CDR). All patients completed neuropsychological evaluation. Agreement in diagnostic classifications between DSM-IV/IWG and DSM-V was examined using the kappa test and AC1 statistic, with multinomial logistic regression for factors contributing to MCI reclassification as major NCDs as opposed to diagnostically concordant MCI and dementia groups. Results: Of 234 patients studied, 166 patients achieved concordant diagnostic classifications, with overall kappa of 0.41. Eighty-six patients (36.7%) were diagnosed with MCI and 131 (56.0%) with DSM-IV-defined dementia. With DSM-V, 40 patients (17.1%) were classified as mild NCDs and 183 (78.2%) as major NCDs, representing a 39.7% increase in frequency of dementia diagnoses. CDR sum-of-boxes score contributed independently to differentiation of MCI patients reclassified as mild versus major NCDs (OR: 0.01; 95% CI: 0-0.09). CDR sum-of-boxes score (OR: 5.18; 95% CI: 2.04-13.15), performance in amnestic (OR: 0.14; 95% CI: 0.06-0.34) and language (Boston naming: OR: 0.52; 95% CI: 0.29-0.94) tests, were independent determinants of diagnostically concordant dementia diagnosis. Conclusion: The authors observed moderate agreement between the different operational definitions and a 40% increase in dementia diagnoses with operationalization of the DSM-V criteria.