Inter-Rater Agreement in the Clinical Diagnosis of Cognitive Status: Data from the Neurological Disorders in Central Spain 2 Pilot Study

Background: To assess the diagnostic agreement of cognitive status (dementia, mild cognitive impairment (MCI), normal cognition) among neurologists in the field of neurological disorders in Central Spain 2 study. Methods: Full medical histories of 30 individuals were provided to 27 neurologists: 9 seniors, 10 juniors and 8 residents. For each case, we were asked to assign a diagnosis of dementia, MCI or normal cognition using the National Institute on Aging-Alzheimer's Association workgroup (NIA-AA) core clinical criteria for all-cause dementia, Winblad et al. criteria for MCI, and analyze intensity and etiology if dementia was diagnosed. Inter-rater agreement was assessed both with percent concordance and non-weighted κ statistics. Results: Overall inter-rater agreement on cognitive status was κ = 0.76 (95% CI 0.65-0.86), being slightly higher among junior neurologists (κ = 0.85, 95% CI 0.73-0.95) than among seniors (κ = 0.71, 95% CI 0.59-0.83) and residents (κ = 0.69, 95% CI 0.54-0.81) but without statistical significance among groups. Dementia severity showed an overall κ of 0.34, 0.44 and 0.64 for mild, moderate and severe dementia respectively. Conclusions: Substantial agreement was demonstrated for the diagnosis of cognitive status (dementia, MCI and normal cognition) among neurologists of different levels of experience in a population-based epidemiological study using NIA-AA and Winblad et al. criteria. The agreement rate was lower in the diagnosis of dementia severity.