A J-shaped relation of BMI and stroke: Systematic review and dose-response meta-analysis of 4.43 million participants.

<bold>Background and Aim: </bold>Many studies have shown increased risk of stroke with greater adiposity as measured by body mass index (BMI), but questions remain about the shape of the dose-response relation. We conducted a systematic review and meta-analysis of prospective studies to clarify the strength and shape of the dose-response relation between BMI and risk of stroke.<bold>Methods and Results: </bold>PubMed and Embase databases were searched for articles published up to May 11, 2018. Random-effects generalized least-squares regression models were used to estimate study-specific dose-response association, and restricted cubic splines were used to model the association. We included reports of 44 prospective cohort studies describing 102 466 incident cases among 4 432 475 participants. With a 5-unit increment in BMI, the summary relative risk for stroke incidence was 1.10 (95% confidence interval, 1.06 to 1.13; I2 = 88.0%). The dose-response relation was J-shaped (Pnon-linearity <0.001). The risk was not increased at the low BMI range (<24 kg/m2), but was increased within the high BMI range (>25 kg/m2).<bold>Conclusion: </bold>Both overweight and obesity increase the risk of stroke with a J-shaped dose-response relation, and the nadir of the curve was observed at BMI 23-24 kg/m2. [ABSTRACT FROM AUTHOR]