Principal Component Analysis of Oxford Cognitive Screen in Patients With Stroke

Abstract

Cognitive deficits occur in most patients with stroke and are the important predictors of adverse long-term outcome. Early identification is fundamental to plan the most appropriate care, including rehabilitation and discharge decisions. The Oxford Cognitive Screen (OCS) is a simple, valid, and reliable tool for the assessment of cognitive deficits in patients with stroke. It contains 10 subtests, providing 14 scores referring to 5 theoretically derived cognitive domains: attention, language, number, praxis, and memory. However, an empirical verification of the domain composition of the OCS subtests in stroke data is still lacking in the literature. A principal component analysis (PCA) was performed on 1,973 patients with stroke who were enrolled in OCS studies in the UK and in Italy. A number of six main components were identified relating to the domains of language and arithmetic, memory, visuomotor ability, orientation, spatial exploration, and executive functions. Bootstrapped split-half reliability analysis on patients and comparison between patients and 498 healthy participants, as that between patients with left and right hemisphere damage, confirmed the results obtained by the principal component analysis. A clarification about the contribution of each score to the theoretical original domains and to the components identified by the PCA is provided with the aim to foster the usability of OCS for both clinicians and researchers.

Oxford cognitive screen: A critical review and independent psychometric evaluation

“…This study found that the OCS is more sensitive to the cognitive sequalae associated with left hemisphere stroke, with patients with right hemisphere strokes only performing worse on measures of visual inattention – although this difference was not statistically significant. This mirrors the findings of previous research (Demeyere et al, 2016; Iosa et al, 2022). This may relate to either a bias in how the assessment is constructed, or the pervasive impact of aphasia and impaired motor control of dominant hand on cognitive assessment, which are more prevalent in left hemisphere stroke.…”

“…Additionally, both studies found that measures of allocentric and egocentric inattention converged into the same factor, which we labelled Visual Inattention. The primary difference in findings between studies is that the present study identified a single‐item factor for visual fields and grouped seemingly disparate cognitive functions into a single variable (‘General cognitive functioning’), whereas Iosa et al (2022) had several single‐item factors, for example orientation, on the basis that they reached a 6‐factor solution.…”

“…In terms of the factor structure of the OCS, this study reported a different factor structure to the theorised structure of the OCS and the recent factor analysis performed by the research team (Iosa et al, 2022). In similarity, both the current and Iosa's factor analyses grouped measures of language and calculation into a single factor, which is in keeping with the emerging evidence base that number processing partly shares an overlapping neural network with language processing (Evans et al, 2016).…”

“…The factor structure of the OCS has also been evaluated. Iosa et al (2022) tested the factor structure of the OCS in a sample of 1973 stroke patients from the United Kingdom and Italy, and 498 healthy controls. Their structure deviated significantly from the theorised factor structure of the OCS, with orientation and executive functioning being comprised of a single subtest each.…”

Association of Neuroimaging Markers on Clinical CT Scans With Domain-Specific Cognitive Impairment in the Early and Later Poststroke Stages

“…Previous research suggests that these analogous OCS/BCoS tasks tap the same underlying cognitive functions and do not significantly differ in sensitivity. 24,25…”