WSO October 2023 – Issue 1 - 890

890
International Journal of Stroke 18(8)
control group, we searched for normative data of the test,
matched, where possible, for age, sex, and education.
Effect size estimation. For calculating the severity of impairment
in different cognitive domains, we distinguished
between the cognitive domains following Lezak et al.'s12
classification: global cognition, visuoconstruction, language,
attention and executive functioning, delayed memory,
immediate memory, working memory, and processing
speed (note that these domains should not be interpreted
too strictly). Then, per study and cognitive domain, we estimated
Hedges' g, a measure of effect size corrected for
small sample sizes, and its corresponding estimated sampling
variance (sample-size-averaged estimator)13 using the
R14 (version 4.1.2) package esc15 in the following way: per
task, we took the reported mean and standard deviation
(SD) to calculate Hedges' g. For scores reported with a
median and interquartile range, we first calculated the mean
and SD using the given median and range.16 When multiple
tasks were used for the same cognitive domain in one study,
we calculated z-scores for the patient group per task (mean
patient - mean controls / SD controls). We then took the
mean and SD of the z-scores within that domain for calculating
Hedges' g per cognitive domain per study.
Meta-analyses
Inferential statistical analyses were carried out with R14
(package metafor).17 The pooled prevalence rates for
impairment were assessed with random-effects meta-analysis
for binominal distributions, using 95% confidence intervals
(CIs) (function " metaprop " ), based on the study's
stroke-sample size (number of observations) and the number
of people with an impairment (number of events).
The pooled estimates for the severity of impairment per
domain were assessed with random-effects meta-analysis
when there was a sufficient number of studies (k ⩾ 5)
reporting on a specific domain, and otherwise with fixedeffects
models (minimum k = 2, otherwise the cognitive
domain was not analyzed).18 We set the alpha level at 0.05
for the severity meta-analyses. We considered effect sizes
between 0.2 and 0.5 as small, between 0.5 and 0.8 as
medium, and >0.8 as large.19
We quantified and evaluated heterogeneity in the metaanalyses
by the I2 statistics and by visually checking the
forest plots with the overlap of the CIs. We considered the
level of heterogeneity based on the guidelines of the
Cochrane Handbook,20 with values over 75% representing
considerable heterogeneity.
Results
Included articles
Six hundred ninety articles were identified. After removing
duplicates (201) and irrelevant articles (460), 29 articles
were eligible for inclusion (Figure 1). It occurred twice that
International Journal of Stroke, 18(8)
two articles reported on the same cohort (Hordaland County
cohort Norway21,22 and Sahlgrenska Academy Study on
Ischemic Stroke Sweden),23,24 but provided different information;
thus, we included both. More than half of the studies
(16/29) included a population of ischemic stroke
only22-37 (Table 1). Time since stroke while evaluating cognitive
outcomes ranged from a few hours to 11 years, but
almost half of the studies (13/29) reported on people in the
chronic phase21-24,26,28,30,31,36,38-41 and the other half (14/29)
included people in the non-chronic phase.25,27,29,32-35,37,42-47
Two studies included both the chronic and non-chronic
phase.48,49 The studies were conducted in 22 different countries.
Exclusion criteria related to the ability to participate
were common across studies: 11 studies reported to have
excluded people with aphasia23,26,28,30,32,35,36,43,45-47 and 6
studies people with dementia.23,32,40,41,45,47
Study quality
The mean quality score of the 29 studies was 6.59 (out of
9 points, SD = 1.49; range = 4-9; median = 6.5, Supplementary
Table S1). All studies included at least some
information about participant and stroke characteristics.
Stroke type was mostly reported (24/29).22-38,40,42,43,45-47,49
Time since stroke was available in all studies. Sixteen
studies reported that they included only first-ever
stroke.21,22,25,26,28-33,36-38,44,47,49 Lesion side (left or right
hemisphere) was reported in 10 studies.24,26,28,30,31,35,36,42,45,47
Stroke was specified with a definition in almost all studies
(24/29).21-23,25-32,34-38,40-42,44-48 Studies scored the lowest
on operationalization of outcome measures and criteria
(e.g. only 13 studies21-23,25,26,28,30,32,35,36,38,43,47 operationalized
impairment in detail with specific cut-off criteria
on the administered tests). Appropriateness of the manner
of assessment also varied between studies. Ten studies27,29,31,33,34,37,39,41,42,49
used a subjective test or did not
report any tests results, seven studies21,25,30,38,40,46,47 used a
cognitive test that only provided a global cognitive score,
and 12 studies22-24,26,28,32,35,36,43-45,48 used tests tapping into
specific cognitive domains. All reported in detail how they
collected data.
Measurement tools
All 29 studies could be used to describe what measurement
tools are used to evaluate cognitive functioning
after stroke in young adults (Supplementary
Table S2). Fourteen studies used a test that measured
global cognition (e.g. the Mini-mental state examination).21,23,24,26,30,32,35,36,38,40,43,44,46,47
Twelve studies used domainspecific
neuropsychological tests.22-26,28,32,35,36,44,45,48
Seven studies reported using both a global cognition and
domain-specific tests.23,24,26,32,35,36,44 Five studies used
self-report questionnaires.24,31,39,42,49 Six studies did not
report on the use of any test, but still reported on cognitive
functioning.27,29,33,34,37,41
WSO October 2023 – Issue 1

Table of Contents for the Digital Edition of WSO October 2023 – Issue 1
