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International Journal of Stroke 19(4)
century.2 In recent years, the " obesity paradox " has been
reported in the scientific literature on stroke.2-4 This phenomenon
counterintuitively indicates that stroke survivors
who are overweight have better mortality and functional
outcomes following a stroke, compared to normal weight.2-5
Although much of the literature has focused on the effects
of being overweight on post-stroke outcomes, it is notable
that people who are underweight (BMI < 18.5 kg/m2)
appear to be worse off compared to people of normal
weight, with an increased risk of mortality2,4-6 and reduced
functional capacity2-5 after a stroke.
The obesity paradox has been examined in systematic
reviews of several cardiovascular diseases including heart
failure7 and myocardial infarction,8 as well as other chronic
diseases such as chronic kidney diease9 and chronic
obstructive pulmonary disease.10 However, the effect of
abnormal body weight (i.e. being underweight, overweight
or obese) on outcomes following stroke is less clear. Several
systematic reviews on this topic have reached conflicting
conclusions.2-6,11,12 Among these systematic reviews, heterogeneity
among included studies, such as variable use of
BMI cut-off points and differences in outcome measures, as
well as reporting and methodological differences have
likely contributed to contradictory findings. Inconsistent
results from these systematic reviews are worthy of further
investigation.
We aimed to synthesize existing systematic reviews in
an umbrella review of the effects of abnormal body weight
on stroke outcomes, with a view to improving our understanding
of the prognosis for stroke survivors with abnormal
body weight. New insights may contribute to clinical
decision-making, prognostic information for patients, their
carers, and researchers' understanding of the role of body
weight in clinically important outcomes.
The research question for this review was:
RQ1. What is the effect of abnormal body weight (underweight,
overweight, or obesity) on mortality and functional
recovery in adults after stroke?
Methods
We adopted the Joanna Briggs Institute Methodology for
Umbrella reviews13 and reported findings in accordance
with the Preferred Reporting Items for Systematic Reviews
and Meta-Analyses (PRISMA) guidelines.14
Identification and selection of reviews
Inclusion criteria for this umbrella review are presented in
Box 1. Systematic reviews not meeting these inclusion criteria
were excluded. Non-systematic reviews, such as narrative
or descriptive reviews, were excluded, along with
conference abstracts and reviews not written in English.
International Journal of Stroke, 19(4)
Box 1. Inclusion criteria.
Design
* Systematic reviews with or without meta-analysis
including data from a variety of study types.
Participants
* Primary studies included adults (>18 years) with
stroke, in all settings and all stages after stroke,
categorized by body weight (Body Mass Index
(BMI)).
Intervention
* No interventions were evaluated in this review.
Comparisons
* Exposure to different weight groups, that is,
normal weight
Outcomes
* All-cause mortality and/or functional recovery at
any time point following stroke
Searches for systematic reviews and meta-analyses were
run in Cumulated Index to Nursing and Allied Health
Literature (CINAHL) Complete, Cochrane Database of
Systematic
Reviews,
EMBASE
Classic + EMBASE,
PubMed, Medline, PEDro, JBI Database of Systematic
Reviews and Implementation Reports, Database of
Abstracts of Reviews of Effects (DARE), and PROSPERO
register from date of inception until 28 February 2023. The
initial search strategy was adapted for each database, and
final search strategies used key words relating to stroke,
body weight, functional recovery, survival, and Medical
Subject Headings (MeSH) terms relevant to each database.
No date restrictions were applied. A manual search of the
reference lists of included reviews was conducted to identify
any eligible studies. The full-search strategy is presented
in Supplemental Table 1 (see eAddenda).
Retrieved studies were managed using Covidence and
Endnote software. Two independent reviewers (S.A.H.,
S.K.) screened titles and abstracts against the eligibility criteria.
Full texts were obtained for studies meeting the inclusion
criteria and were independently reviewed by the same
two reviewers. Disagreements were resolved through discussion
or by a third reviewer (I.W.). Reasons for excluding
articles after full-text review were documented.
Assessment of characteristics
We used an adapted version of the JBI data extraction
form.13 Extracted data included systematic review details
(authors, year, and country), number of included studies,
number of included participants and their age range, aims
and objectives, eligibility criteria, search strategy, heterogeneity,
outcome measures and weight categories assessed,
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