Validation of the UK English Oxford cognitive screen-plus in sub-acute and chronic stroke survivors

Abstract

Introduction: Stroke survivors are routinely screened for cognitive impairment with tools that often fail to detect subtle impairments. The Oxford Cognitive Screen-Plus (OCS-Plus) is a brief tablet-based screen designed to detect subtle post-stroke cognitive impairments. We examined its psychometric properties in two UK English-speaking stroke cohorts (subacute: <3 months post-stroke, chronic: >6 months post-stroke) cross-sectionally. Patients and methods: This study included 347 stroke survivors (mean age = 73 years; mean education = 13 years; 43.06% female; 74.42% ischaemic stroke). The OCS-Plus was completed by 181 sub-acute stroke survivors and 166 chronic stroke survivors. All participants also completed the Oxford Cognitive Screen (OCS) and a subset completed the Montreal Cognitive Assessment (MoCA) and further neuropsychological tests. Results: First, convergent construct validity of OCS-Plus tasks to task-matched standardized neuropsychological tests was confirmed (r > 0.30). Second, we evaluated divergent construct validity of all OCS-Plus subtasks (r < 0.19). Third, we report the sensitivity and specificity of each OCS-Plus subtask compared to neuropsychological test performance. Fourth, we found that OCS-Plus detected cognitive impairments in a large proportion of those classed as unimpaired on MoCA (100%) and OCS (98.50%). Discussion and conclusion: The OCS-Plus provides a valid screening tool for sensitive detection of subtle cognitive impairment in stroke patients. Indeed, the OCS-Plus detected subtle cognitive impairment at a similar level to validated neuropsychological assessments and exceeded detection of cognitive impairment compared to standard clinical screening tools.