Impact of different methods defining post‐stroke neurocognitive disorder: The Nor‐COAST study

INTRODUCTION: Post‐stroke neurocognitive disorder (NCD) is common; prevalence varies between studies, partially related to lack of consensus on how to identify cases. The aim was to compare the prevalence of post‐stroke NCD using only cognitive assessment (model A), DSM‐5 criteria (model B), and the Global Deterioration Scale (model C) and to determine agreement among the three models. METHODS: In the Norwegian Cognitive Impairment After Stroke study, 599 patients were assessed 3 months after suffering a stroke. RESULTS: The prevalence of mild NCD varied from 174 (29%) in model B to 83 (14%) in model C; prevalence of major NCD varied from 249 (42%) in model A to 68 (11%) in model C. Cohen's kappa and Cohen's quadratic weighted kappa showed fair to very good agreement among models; the poorest agreement was found for identification of mild NCD. DISCUSSION: The findings indicate a need for international harmonization to classify post‐stroke NCD.