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International Journal of Stroke 19(3)
Introduction
Though the prevalence of post-stroke cognitive impairment
varies depending on the timing, assessment, and inclusion
criteria, most stroke survivors experience at least one cognitive
deficit.1,2 Identifying which cognitive impairments
more commonly occur, recover, and persist will aid in intervention
planning and setting rehabilitation goals.
Early post-stroke cognitive assessment is recommended
in clinical guidelines and best practice statements.3-6 The
Oxford Cognitive Screen (OCS)7,8 is a short, domain-specific
cognitive screen which compromises between the benefits
of global tests and neuropsychological batteries. The
OCS offers superior patient inclusivity and sensitivity than
brief screens (e.g. the Mini-Mental State Examination
(MMSE) and Montreal Cognitive Assessment (MoCA)).1,9
It also assesses multiple domains much like a neuropsychological
battery, which is in line with clinical guidance.
Acute domain impairments are highly prevalent after
stroke;1 however, the prevalence and trajectories of domainspecific
impairment beyond the acute stage are relatively
unknown. In addition, while the OCS has recently been
shown to provide value information regarding functional
outcomes,10 it has not been established whether the short
screen had prognostic value in determining longer-term
cognitive outcome.
Very few studies have considered acute post-stroke cognitive
performance in longer-term outcome prediction models,
and instead, the focus tends to be on clinical and
neuroimaging markers.11 A few previous studies have aimed
to predict outcomes using brief global screens12 (e.g. the
MoCA).13-17 Acute MoCA scores predict long-term cognitive
and functional outcome, and mortality.13 However, the
MoCA is not always suitable for stroke as it assumes cognitive
functions (e.g. speech, vision) are intact. Consequently,
common post-stroke impairments (e.g. aphasia, neglect) can
confound assessment.9,12
One study used a multi-domain neuropsychological battery
to investigate the prognostic value of early cognitive
assessment18,19 and found acute performance to predict
6-month cognitive and functional outcome better than
demographic or clinical variables.19 These findings support
the utility of cognitive data; however, a large neuropsychological
battery (>1 h) is typically not feasible in routine
acute clinical practice due to time requirements and
increased burden on the patient, as well as staff availability
and expertise.
This study aimed to use the OCS to (1) determine the
prevalence of domain-specific cognitive impairments
acutely and at 6 months post-stroke, (2) assess change in
function across timepoints, and (3) examine the predictive
value of early domain-specific screening. Importantly, this
study does not aim to build optimal prognostic models
employing all potential predictors (e.g. genetic risk) but
instead aims to determine the value added by considering
International Journal of Stroke, 19(3)
cognitive data. Ultimately, this could lead to practical prognostic
models based on routinely collected and easily
accessible data, promoting informed and efficient clinical
decision-making.
Methods
This study considered existing data from the OCS-Tablet
and OCS-Recovery studies (National Research Ethics
Committee (UK), references 14/LO/0648 and 18/
SC/0550, in accordance with the Declaration of Helsinki).
Patients (⩾18 years old) were included if they could provide
written/witnessed informed consent, could concentrate
for 20 min, and had sufficient English language
comprehension.
Participants
A consecutive sample of acute stroke patients was recruited
from the John Radcliffe Hospital, UK, acute stroke unit
(2012-2019). In total, 866 patients were assessed acutely
(⩽2 weeks), with 430 (49.7%) completing 6-month followup
(Figure 1).
Cognitive assessment
The OCS was used for acute and follow-up cognitive
screening.7 The OCS covers a broad range of cognitive
domains and was designed specifically for use in acute
stroke taking 15-20 min to complete. Subtests are categorized
into six domains: language (picture naming, semantic
understanding, and sentence reading), attention (egocentric
and allocentric attention; broken hearts test), executive
function (trail-making test), memory (orientation, verbal,
and episodic memory; delayed recall/recognition), praxis
(meaningless gesture imitation), and number processing
(calculations and number writing). Each task has a threshold
cut-off to indicate impairment based on published normative
data.7,8 Subtests were binarized into impaired or
unimpaired based on normative scores for each subtest.
Domains were considered impaired if there is at least one
subtest in the domain (e.g. language impaired if reading,
naming, or semantics impaired). Subtests range from one to
three across domains. The OCS was administered by trained
neuropsychologists and occupational therapists. The OCS
is licensed through Oxford University Innovations free of
charge for publicly funded research and clinical use. Further
information regarding administration of the OCS is detailed
in supplemental methods.
Statistical analysis
Descriptive statistics were used to summarize the prevalence
of cognitive impairment/recovery as cognitive data
were limited to binarized outcome. Associations between
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