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

Background 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 guidelines. Studies investigating the association between abnormal body weight and the outcome of different types of stroke were searched in PubMed and Embase databases from their inception to March 20, 2021. Results 33 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, while underweight was related to shorter survival; the pooled hazard ratios (HRs) of mortality were 0.77 (95% confidence interval [CI]: 0.71 to 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 got 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, while underweight was associated with a shorter survival time.