Cognitive and Mood Assessment in Stroke Research
Focused Review of Contemporary Studies
Background and Purpose—International guidelines recommend cognitive and mood assessments for stroke survivors; these assessments also have use in clinical trials. However, there is no consensus on the optimal assessment tool(s). We aimed to describe use of cognitive and mood measures in contemporary published stroke trials.
Methods—Two independent, blinded assessors reviewed high-impact journals representing: general medicine (n=4), gerontology/rehabilitation (n=3), neurology (n=4), psychiatry (n=4), psychology (n=4), and stroke (n=3) January 2000 to October 2011 inclusive. Journals were hand-searched for relevant, original research articles that described cognitive/mood assessments in human stroke survivors. Data were checked for relevance by an independent clinician and clinical psychologist.
Results—Across 8826 stroke studies, 488 (6%) included a cognitive or mood measure. Of these 488 articles, total number with cognitive assessment was 408 (83%) and mood assessment tools 247 (51%). Total number of different assessments used was 367 (cognitive, 300; mood, 67). The most commonly used cognitive measure was Folstein's Mini-Mental State Examination (n=180 articles, 37% of all articles with cognitive/mood outcomes); the most commonly used mood assessment was the Hamilton Rating Scale of Depression(n=43 [9%]).
Conclusions—Cognitive and mood assessments are infrequently used in stroke research. When used, there is substantial heterogeneity and certain prevalent assessment tools may not be suited to stroke cohorts. Research and guidance on the optimal cognitive/mood assessment strategies for clinical practice and trials is required.
Cognitive and mood disorders are common stroke sequelae, each affecting approximately one third of stroke survivors.1 These complications can impair functional recovery2,3 and are important to patients. A recent national priority setting exercise identified “psychological problems” (particularly dementia and depression) as the most important but underresearched issues for stroke survivors and caregivers.4 The importance of cognition and mood is recognized in international guidelines, where their routine assessment is recommended for all stroke survivors.5
In clinical stroke trials, end points are usually based around domains of physical function, quality of life, and mortality.6 There is potential benefit in assessing cognition and mood, both at study recruitment and as the end point. For intervention trials, stroke survivors with substantial cognitive or mood deficits may be excluded. However, lesser problems with mood and cognition may still impact on activity and participation outcomes and should be described. Because they have potential effects on all aspects of recovery, some have argued that cognitive measures themselves may be a useful “global outcome” measure for trials.7
Many cognitive/mood assessment instruments are available, but at present, there is no consensus on optimal measure(s) for use in stroke practice or research. A literature around stroke trial assessment is emerging, although to date there has been limited research on the properties of common cognitive/mood assessments in stroke. We first have to know which tools are commonly used. We sought to describe the cognitive/mood assessments used in contemporary published stroke trials.
We used a sensitive, focused literature search strategy. After informal review of various titles, we restricted analysis to 16 journals selected based on relevance to stroke, impact factor, and proportion of clinical studies. After external review and advice, a further 6 journals were added to broaden the scope of the search. Journals representing general medicine; geriatric medicine/rehabilitation; neurology; psychology; psychiatry; and stroke were included (Figure).
Journals were hand-searched for relevant articles January 2000 to October 2011 inclusive reviewing all content, including letters and short reports. Inclusion criteria were original research in adult, human stroke survivors. From these studies, we extracted details on any cognitive or mood assessments used (including inclusion/exclusion criteria; primary outcome and secondary outcome[s]). Selection was deliberately inclusive. Where additional methodology was described in an online or paper supplement, this was accessed. We did not contact authors of articles. Where a data set was used more than once with the same outcomes, only the primary article was considered.
We used inclusive definitions of cognitive measures (any aspect of cognitive function including language and visuospatial/constructional skills) and mood. Quality of life or global measures were included if they had specific cognitive/mood components. Caregiver assessments and proxy assessments were included if they related to mood/cognition. Fatigue scales were not considered.
Two researchers (R.L. and J.K.H.) independently hand-searched journals and compared results. Resulting lists of cognitive and mood measures were checked for relevance by an independent clinician (T.J.Q.) and clinical psychologist (N.M.B.). Final decision on inclusion was by group discussion and consensus. As a further validity check, an independent, blinded researcher (P.F.) hand-searched a random selection of 4 journals and 4 years. This search did not reveal any new studies, suggesting validity of the original searches. We described outcomes as absolute numbers of assessments and proportions.
Across 22 journals, the total number of articles was 80 988 with 8826 articles detailing stroke-related original research. Of these 488 (6%) had used cognitive or mood assessment scales.
The total number of different cognitive/mood assessments was 367. Of 67 mood assessment scales used in 247 articles, the most prevalent was the Hamilton Rating Scale for Depression (n=43 [9% of all articles with cognitive/mood assessment]). Of 300 cognitive assessment tools (n=408 articles), 15 (5%) were diagnostic tests; 86 (29%) were neuropsychological test batteries or assessed multiple cognitive domains; the remainder assessed single domains. The most prevalent assessment were Folstein's Mini-Mental State Examination (n=180 [37%]; Table; online-only Data Supplement).
Where cognitive/mood assessments were used, median number of tests was 2 (interquartile range, 1–3; range, 1–21). A cognitive/mood measure was used as primary outcome in 353 (72% of articles with cognitive/mood measure); secondary outcome in 56 (11%); and as inclusion/exclusion criteria in 59 (12%). Psychiatry journals were most likely to detail cognitive/mood outcomes in stroke survivors (n=41 studies), although the absolute number of stroke studies in psychiatry journals was modest (n=75).
Despite the clinical importance of cognitive and mood disorders, these aspects of stroke are infrequently measured in clinical trials. Cognitive/mood measures are most often used as the primary outcome, suggesting that trialists only measure these domains in studies focused on neuropsychology of stroke. Our data suggest limited overlap between disciplines; psychology/psychiatry journals measure cognition/mood but infrequently study stroke cohorts; the converse is true of neurology journals. Given the potential effect of cognitive/mood disorder on global functional outcome,2,3 trialists are failing to measure what could be an important outcome (or indeed confounder).
When cognitive/mood assessments are used, there is heterogeneity. We note there were almost as many cognitive measures as there were studies describing cognitive function. This in part relates to our inclusive definition, comprising cognitive screening/assessment; single and multidomain neuropsychological testing; and diagnostic criteria. Even limiting to single-domain cognitive tests, the substantial heterogeneity in assessment strategies precludes meaningful between study comparisons and meta-analyses.
Certain prevalent cognitive/mood assessments may not be appropriate for stroke cohorts; for example, the Mini-Mental State Examination is not particularly suited to vascular cognitive impairment.8 Conversely, certain scales prevalent in clinical practice9 and with evidence of use in stroke10 were infrequently used; for example, the Montreal Cognitive Assessment (n=2 articles) and the Repeatable Battery for the Assessment of Neuropsychological Status (n=1 article). Despite the variety of validated tools available, some authors continue to use their own bespoke assessment scales. As well as illustrating heterogeneity in assessments, our list of outcomes can be used to inform search strategies for future systematic reviews of diagnostic accuracy.
Our study used a sensitive search strategy, using hand-searching and various validity checks. This approach has previously been successfully used to describe functional outcomes in the stroke literature.6 The increasing volume and multidisciplinary nature of stroke research precluded review across all studies.11 However, our intention was to describe outcome assessments in popular medical journals rather than across the complete stroke literature. Our choice of journals was in keeping with other studies that have used similar methods.12
Stroke trialists and clinicians are unlikely to be surprised by our findings; it has long been suspected that we are failing to capitalize on the potential of cognitive and mood assessments.6,7 Our data provide evidence to support this view and we hope provide further clear incentive to look toward standardizing assessments across studies. We would recommend that stroke trialists and clinicians work to produce guidance on preferred outcome measures for cognitive and mood disorders informed by robust descriptions of test accuracy and clinimetric properties of scales in stroke.
Sources of Funding
This work was supported by Chest Heart and Stroke Scotland.
Costantino Iadecola, MD, was the Guest Editor for this paper.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.111.653303/-/DC1.
- Received February 6, 2012.
- Accepted February 16, 2012.
- © 2012 American Heart Association, Inc.
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