Association of Body Mass Index and Risk of Stroke After Acute Minor Stroke or TIA: a Post Hoc Analysis of a Randomized Controlled Trial

The effect of body mass index on stroke prognosis: A systematic review and meta-analysis of 32 cohort studies with 330,353 patients

BACKGROUND

Many studies have explored the impact of body mass index (BMI) on stroke prognosis, yet findings remain inconsistent.

AIMS

The aims of this study were to conduct a systematic review and meta-analyses to summarize the existing evidence on BMI and stroke outcomes.

METHODS

PubMed, Web of Science, Embase, The Cochrane Library, CNKI, CBM, Wanfang Database, and VIP Database were systematically searched from inception to 1 January 2023. Cohort studies were included if they reported on a population of patients with stroke, evaluated BMI on stroke outcomes (mortality/recurrence/score of modified Rankin scale (mRs)), and reported original data. Data extraction and quality assessment were independently undertaken by two reviewers. Stata 16.0 software was used for meta-analysis.

RESULTS

Thirty-two studies involving 330,353 patients (5 Chinese language articles) were included in the analysis. The proportion of underweight, overweight, and obese patients was 1.85%, 18.2%, and 15.6%, respectively. Compared with normal weight, being underweight was associated with an increased risk of mortality (relative risk (RR) = 1.78, 95% confidence interval (CI) = 1.60-1.96), poor functional outcomes defined as modified Rankin scale ⩾ 3 (RR = 1.33, 95% CI = 1.22-1.45), and stroke recurrence (RR = 1.19, 95% CI = 1.04-1.37). Being overweight but not obese was associated with reduced mortality (RR = 0.81, 95% CI = 0.74-0.89) and better functional outcomes (RR = 0.92, 95% CI = 0.89-0.96), but did not alter the risk of stroke recurrence (RR = 1.03, 95% CI = 0.90-1.17). Obesity was associated with lower risk of mortality (RR = 0.76, 95% CI = 0.72-0.81) and better functional outcomes (RR = 0.89, 95% CI = 0.84-0.94).

CONCLUSIONS

Our findings indicate that in patients with stroke, being underweight is associated with an increased risk of mortality, poor functional outcomes, and stroke recurrence. In contrast, being overweight but not obese, or being obese, was associated with a decreased risk of mortality and better functional outcomes. This is consistent with the obesity paradox in stroke, whereby obesity increases stroke risk in the general population but is associated with improved outcome in patients suffering stroke.

Effects of body mass index on the immune response within the first days after major stroke in humans

INTRODUCTION

Immunological alterations associated with increased susceptibility to infection are an essential aspect of stroke pathophysiology. Several immunological functions of adipose tissue are altered by obesity and are accompanied by chronic immune activation. The purpose of this study was to examine immune function (monocytes, granulocytes, cytokines) as a function of body mass index (BMI: 1st group: 25; 2nd group: 25 BMI 30; 3rd group: 30) and changes in body weight post stroke.

METHOD

Fat status was assessed using standardized weight measurements on days 1, 2, 3, 4, 5, and 7 after ischemic stroke in a cohort of 40 stroke patients and 16 control patients. Liver fat and visceral fat were assessed by MRI on day 1 or 2 [I] and on day 5 or 7 [II]. Leukocyte subpopulations in peripheral blood, cytokines, chemokines, and adipokine concentrations in sera were quantified. In a second cohort (stroke and control group, n = 17), multiple regression analysis was used to identify correlations between BMI and monocyte and granulocyte subpopulations.

RESULTS

Weight and fat loss occurred from the day of admission to day 1 after stroke without further reduction in the postischemic course. No significant changes in liver or visceral fat were observed between MRI I and MRI II. BMI was inversely associated with IL-6 levels, while proinflammatory cytokines such as eotaxin, IFN-β, IFN -γ and TNF-α were upregulated when BMI increased. The numbers of anti-inflammatory CD14+CD16+ monocytes and CD16+CD62L- granulocytes were reduced in patients with higher BMI values, while that of proinflammatory CD16dimCD62L+ granulocytes was increased.

CONCLUSION

A small weight loss in stroke patients was detectable. The data demonstrate a positive correlation between BMI and a proinflammatory poststroke immune response. This provides a potential link to how obesity may affect the clinical outcome of stroke patients.

Non-linear association between body weight and functional outcome after acute ischemic stroke

This study aimed to determine whether body weight is associated with functional outcome after acute ischemic stroke. We measured the body mass index (BMI) and assessed clinical outcomes in patients with acute ischemic stroke. The BMI was categorized into underweight (< 18.5 kg/m²), normal weight (18.5-22.9 kg/m²), overweight (23.0-24.9 kg/m²), and obesity (≥ 25.0 kg/m²). The association between BMI and a poor functional outcome (modified Rankin Scale [mRS] score: 3-6) was evaluated. We included 11,749 patients with acute ischemic stroke (70.3 ± 12.2 years, 36.1% women). The risk of a 3-month poor functional outcome was higher for underweight, lower for overweight, and did not change for obesity in reference to a normal weight even after adjusting for covariates by logistic regression analysis. Restricted cubic splines and SHapley Additive exPlanation values in eXtreme Gradient Boosting model also showed non-linear relationships. Associations between BMI and a poor functional outcome were maintained even after excluding death (mRS score: 3-5) or including mild disability (mRS score: 2-6) as the outcome. The associations were strong in older patients, non-diabetic patients, and patients with mild stroke. Body weight has a non-linear relationship with the risk of a poor functional outcome after acute ischemic stroke.

Does bariatric surgery change the risk of acute ischemic stroke in patients with a history of transient ischemic attack? A nationwide analysis

BACKGROUND

Stroke is the second leading cause of death worldwide and fifth in the United States, and it represents the major cause of disability in older adults.

OBJECTIVE

We aimed to determine the risk of acute ischemic stroke (AIS) in individuals with obesity with a history of transient ischemic attack (TIA) compared with patients with a history of bariatric surgery.

SETTING

Academic hospital, United States.

METHODS

Using the Nationwide Inpatient Sample (NIS) database from 2010 to 2015, we retrospectively identified patients with obesity and past medical history of TIA and divided them into 2 groups: a treatment group of patients who underwent bariatric surgery, and a control group of patients with obesity. We compared incidence of new AIS in both groups using a univariate analysis and multivariate regression model. Covariates included were lifestyle (smoking status, alcohol habits, cocaine use), family history of stroke, co-morbidities (diabetes, hypertension, hyperlipidemia, atrial fibrillation) and long-term medical treatment (antiplatelet/antithrombotic treatment).

RESULTS

A total of 91,640 patients met inclusion criteria, of which treatment patients were 12.3% (n = 11,284) and control patients 87.6% (n = 80,356). The average age of the treatment group was 62.9 ± 17.08 years, and the average of the control was 59.6 ± 12.74 years. The rate of AIS in the treatment group was significantly lower compared with the control group (2.8% versus 4.2%, P < .0001). After adjusting for covariables, the risk difference of AIS was still significant between groups (odds ratio = 1.33, P < .0001), showing that patients in the treatment group were less likely to have AIS compared with the control group.

CONCLUSIONS

After analyzing nationwide information, we conclude bariatric surgery helps decrease risk of AIS in patients with a history of TIA. However, this comparison is limited by the nature of the database; further studies are needed to better understand these results.

Naoxintong Capsule for Secondary Prevention of Ischemic Stroke: A Multicenter, Randomized, and Placebo-Controlled Trial

OBJECTIVE

To examine whether the combination of Naoxintong Capsule with standard care could further reduce the recurrence of ischemic stroke without increasing the risk of severe bleeding.

METHODS

A total of 23 Chinese medical centers participated in this trial. Adult patients with a history of ischemic stroke were randomly assigned in a 1:1 ratio using a block design to receive either Naoxintong Capsule (1.2 g orally, twice a day) or placebo in addition to standard care. The primary endpoint was recurrence of ischemic stroke within 2 years. Secondary outcomes included myocardial infarction, death due to recurrent ischemic stroke, and all-cause mortality. The safety of drugs was monitored. Results were analyzed using the intention-to-treat principle.

RESULTS

A total of 2,200 patients were enrolled from March 2015 to March 2016, of whom 143 and 158 in the Naoxintong and placebo groups were lost to follow-up, respectively. Compared with the placebo group, the recurrence rate of ischemic stroke within 2 years was significantly lower in the Naoxintong group [6.5% vs. 9.5%, hazard ratio (HR): 0.665, 95% confidence interval (CI): 0.492-0.899, P=0.008]. The two groups showed no significant differences in the secondary outcomes and safety, including rates of severe hemorrhage, cerebral hemorrhage and subarachnoid hemorrhage (P>0.05).

CONCLUSION

The combination of Naoxintong Capsule with standard care reduced the 2-year stroke recurrence rate in patients with ischemic stroke without increasing the risk of severe hemorrhage in high-risk patients. (Trial registration No. NCT02334969).

The relationship between body mass index and stroke: a systemic review and meta-analysis

BACKGROUND

Stroke is an acute cerebrovascular event closely related to brain tissue damage, and is one of the major causes of death and disability in worldwide. Various studies have reported the effects of body mass index (BMI) on the risk of stroke, but the results remain varied and these results have not been synthesized. Therefore, a meta-analysis was performed to evaluate the relationship between BMI and the risk of stroke.

OBJECTIVES

This systematic review was conducted to explore the relationship between BMI and the risk of stroke.

METHODS

PubMed, EMBASE, Web of Science and Cochrane Library, China Knowledge Resource Integrated Database (CNKI), WanFang Database, Chinese Biomedical Database (CBM), and CQVIP were comprehensively searched for studies exploring the relationship between BMI and stroke from inception to December 1, 2021.

RESULTS

This review included 24 studies involving 5,798,826 subjects. The results of meta-analysis showed that the pooled RR of stroke risk was 0.93 (95% confidence interval [CI] 0.82-1.06, I² = 88.8%, P = 0.29) for the underweight group. Higher BMI (overweight or obese group) was associated with an increased overall risk of stroke, with pooled RR values of 1.25 (95% CI 1.16-1.34, I² = 84.8%, P = 0.00) and 1.47 (95% CI: 1.02-2.11, I² = 99.4%, P = 0.04).

CONCLUSION

The risk of stroke was positively correlated with BMI, and the association was stronger in male and ischemic stroke. Lowering BMI can be used as a way to prevent stroke, and for people who are overweight or obese, lowering body weight can reduce the risk of stroke.

Association between abnormal body weight and stroke outcome: A meta-analysis and systematic review

BACKGROUND AND PURPOSE

To test the hypothesis that "obesity paradox" exists in stroke patients, we conducted a meta-analysis and systematic review on the association between abnormal body weight (obesity, overweight, or underweight) and the outcome of different types of stroke.

METHODS

This meta-analysis and systematic review was performed in conformity to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines in Appendix S2. Studies investigating the association between abnormal body weight and the outcome of different types of stroke were searched for in the PubMed and Embase databases from their inception to 20 March 2021.

RESULTS

Thirty-three articles including 84,660 patients were included in this study. Obesity and overweight were associated with longer survival in mixed-stroke patients (acute ischemic stroke [AIS] combined with one or more other stroke subtypes) than was normal weight, whereas underweight was related to shorter survival; the pooled hazard ratios (HRs) of mortality were 0.77 (95% confidence interval [CI] = 0.71-0.83) for obesity, 0.76 (95% CI = 0.72-0.80) for overweight, and 1.71 (95% CI = 1.56-1.87) for underweight. However, only obesity was associated with longer survival in AIS patients compared with normal weight, and underweight was related to shorter survival; the pooled HR of mortality was 0.75 (95% CI = 0.64-0.88) for obesity and 1.53 (95% CI = 1.27-1.85) for underweight. After merging mixed-stroke and AIS patients, we obtained similar results as in mixed-stroke patients.

CONCLUSIONS

Our results suggested that in patients with mixed stroke or AIS, obesity was associated with a longer survival time than normal weight, whereas underweight was associated with a shorter survival time.

An Analysis of the Potential Relationship of Triglyceride Glucose and Body Mass Index With Stroke Prognosis

Background: The inverse association between obesity and outcome in stroke patients (known as the obesity paradox) has been widely reported, yet mechanistic details explaining the paradox are limited. The triglyceride glucose (TYG) index has been proposed as a marker of insulin resistance. We sought to explore possible associations of the TYG index, body mass index (BMI), and stroke outcome. Methods: We identified 12,964 ischemic stroke patients without a history of diabetes mellitus from the China National Stroke Registry and classified patients as either low/normal weight, defined as a BMI <25 kg/m2, or overweight/obese, defined as a BMI ≥ 25 kg/m2. We calculated TYG index and based on which the patients were divided into four groups. A Cox or logistic regression model was used to evaluate the association between BMI and TYG index and its influence on stroke outcomes, including stroke recurrence all-cause mortality and poor outcome (modified Rankin Scale score of 3-6) at 12 months. Results: Among the patients, 63.3% were male, and 36.7% were female, and the mean age of the patient cohort was 64.8 years old. The median TYG index was 8.62 (interquartile range, 8.25-9.05). After adjusting for multiple potential covariates, the all-cause mortality of overweight/obese patients was significantly lower than that of the low/normal weight patients (6.17 vs. 9.32%; adjusted hazard ratio, 0.847; 95% CI 0.732-0.981). The difference in mortality in overweight/obese and low/normal weight patients with ischemic stroke was not associated with TYG index, and no association between BMI and TYG index was found. Conclusion: Overweight/obese patients with ischemic stroke have better survival than patients with low/normal weight. The association of BMI and stroke outcome is not changed by TYG index.

Metabolically healthy obesity and risk of stroke: a meta-analysis of prospective cohort studies

Background

Metabolic healthy obesity (MHO) is a unique subgroup of overweight and obese individuals with normal metabolic characteristics. Its association with the risk of stroke remains unclear. We aimed to examine the risk of stroke in MHO individuals and the further associations between stroke and metabolic abnormalities under different bodyweight conditions.

Methods

We systematically searched PubMed, Embase and Cochrane Library from December 1946 to January 2019, and only included prospective cohort studies. Random effects models were used to evaluate the pooled risk ratios (RR) and 95% confidence intervals (95% CI) of incident stroke.

Results

A total of eight studies comprising 4,256,888 participants were included in the meta-analysis. MHO individuals had an increased risk of stroke compared with metabolically healthy normal weight (MH-NW) individuals (RR =1.17, 95% CI: 1.11–1.23). However, the stroke risk of metabolically healthy overweight individuals was the same (RR =1.02, 95% CI: 0.84–1.23). All groups with unhealthy metabolism had a similarly elevated risk: normal weight (RR =1.83, 95% CI: 1.57–2.14), overweight (RR =1.93, 95% CI: 1.44–2.58), and obesity (RR =2.00, 95% CI: 1.40–2.87).

Conclusions

The meta-analysis confirms a positive association between MHO phenotype and the risk of stroke. Individuals with metabolic abnormalities under different bodyweight conditions are at elevated risk.

Prior Stroke in PFO Patients Is Associated With Both PFO-Related and -Unrelated Factors

Background and Purpose: To identify factors associated with prior stroke at presentation in patients with cryptogenic stroke (CS) and patent foramen ovale (PFO).

Methods: We studied cross-sectional data from the International PFO Consortium Study (NCT00859885). Patients with first-ever stroke and those with prior stroke at baseline were analyzed for an association with PFO-related (right-to-left shunt at rest, atrial septal aneurysm, deep venous thrombosis, pulmonary embolism, and Valsalva maneuver) and PFO-unrelated factors (age, gender, BMI, hypertension, diabetes mellitus, hypercholesterolemia, smoking, migraine, coronary artery disease, aortic plaque). A multivariable analysis was used to adjust effect estimation for confounding, e.g., owing to the age-dependent definition of study groups in this cross-sectional study design.

Results: We identified 635 patients with first-ever and 53 patients with prior stroke. Age, BMI, hypertension, diabetes mellitus, hypercholesterolemia, coronary artery disease, and right-to-left shunt (RLS) at rest were significantly associated with prior stroke. Using a pre-specified multivariable logistic regression model, age (Odds Ratio 1.06), BMI (OR 1.06), hypercholesterolemia (OR 1.90) and RLS at rest (OR 1.88) were strongly associated with prior stroke.Based on these factors, we developed a nomogram to illustrate the strength of the relation of individual factors to prior stroke.

Conclusion: In patients with CS and PFO, the likelihood of prior stroke is associated with both, PFO-related and PFO-unrelated factors.