Association of body mass index and waist-to-height ratio with outcomes in ischemic stroke: results from the Third China National Stroke Registry

BACKGROUND AND PURPOSE: Conflicting reports of obesity paradox have led to confusion about weight management strategies for post-stroke patients. The main purpose of this study is to determine whether the obesity paradox measured by body mass index (BMI) or by waist-to-height ratio (WHtR) is real. METHODS: We evaluated the association of general obesity measured by BMI, and abdominal obesity measured by WHtR with 1-year all-cause mortality, recurrence of stroke and combined vascular events of acute ischemic stroke (AIS) patients in a cohort —— the Third China National Stroke Registry (CNSR-III). Cox proportional hazards models and restricted cubic splines were performed to investigate the association between obesity and clinical outcomes. RESULTS: A total of 14,146 patients with ischemic stroke were included. When BMI was used as a measure of obesity, compared to the normal weight patients, mortality decreased in overweight patients (hazard ratio [HR] 0.74 [95% confidence interval (CI) 0.61–0.91], P = 0.0035) and obese patients (HR 0.54 [0.40–0.73], P < 0.0001); and increased in underweight patients (HR 2.55 [1.75–3.73], P < 0.0001). After adjustment for confounding factors, the protective effect of obesity and overweight disappeared. BMI had no association with recurrence of stroke or combined vascular events. When WHtR was used as a measure of obesity, obese patients had lower 1-year all-cause mortality (HR 0.64 [0.43–0.97], P = 0.0357). After adjustment for confounding factors, this difference disappeared; overweight patients still had lower all-cause mortality (adjusted hazard ratio [aHR] 0.42 [0.26–0.67], P = 0.0003), recurrence of stroke (aHR 0.77 [0.60–0.99], P = 0.0440) and combined vascular events (aHR 0.75 [0.58–0.95], P = 0.0198). CONCLUSIONS: Among Chinese patients with AIS, our study does not support the BMI paradox; overweight patients measured by WHtR had a more favorable prognosis. TOAST subtypes did not modify the association. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12883-023-03165-y.