Abstract WP154: Exploring the Obesity Paradox: Associations of BMI, WHR, and Their Combination with Stroke Recurrence and All-Cause Mortality in the UK Biobank

Background: Obesity is a known risk factor for cardiovascular disease and stroke. However, many studies have shown that higher body weight may be associated with lower mortality in patients with established disease. Body mass index (BMI) is widely used but cannot distinguish fat distribution, while waist-to-hip ratio (WHR) better reflects central obesity. This study examined the independent and combined effects of BMI and WHR on stroke recurrence and all-cause mortality. Methods: We included 2366 UK Biobank participants with a history of only one previous stroke. Baseline demographics, clinical factors, and lifestyle variables were collected. Missing data were handled by multiple imputation. Cox proportional hazards models assessed the associations of BMI(≥25 vs <25 kg/m2), WHR(elevated vs normal), and their combinations with recurrence and mortality, adjusting for major confounders，such as age, sex, smoking, blood pressure, diabetes, hyperlipidemia, deprivation index, and the use of lipid-lowering, antidiabetic, and antihypertensive medications. Results: Over a mean follow-up of 11.9 years for recurrence and 13.4 years for mortality, 313 (13.2%) had recurrence and 735 (31%) died. Higher BMI was associated with reduced mortality risk (adjusted HR 0.77, 95% CI 0.63–0.94) but not recurrence. Elevated WHR was associated with increased risks of recurrence and mortality in unadjusted models, but these associations attenuated after adjustment. In combined analysis, participants with BMI <25 and elevated WHR had the highest unadjusted risks（recurrence HR1.69 95%CI 1.02-2.80；mortality HR 1.76 95%CI 1.28-2.41）, which were no longer significant after adjustment. （ Detailed results are presented in the table. ） Conclusion: In post-stroke populations, higher BMI was associated with a protective effect against all-cause mortality. Elevated WHR was initially associated with increased recurrence and mortality risks, but these associations were attenuated after adjustment. Concurrent elevation of BMI and WHR did not increase the risk. These findings suggest that the influence of obesity on stroke prognosis is complex, highlighting the need for further research to clarify the impact of obesity on stroke outcomes.