[Mediating effect of hypertension on risk of stroke associated with hyperuricemia]

Objective: To investigate the association between hyperuricemia and the risk for stroke occurrence, as well as the mediating effect of hypertension on this association. Methods: In this study, the China Chronic Diseases and Nutrition Surveillance system in 2015 was used as baseline data. We identified hospital admissions for stroke using the electronic homepage of inpatient medical records from 2013-2020, and death data were obtained from the 2015-2020 National Mortality Surveillance System. A retrospective cohort was established after matching and linking the database. The Cox proportional hazard regression model was used to analyze the relationship between hyperuricemia and the risk of stroke and its subtypes. Restricted cubic spline analysis was conducted to examine the dose-response relationship between serum uric acid levels and the risk for stroke. Mediation analysis was performed to investigate the mediating effect of hypertension on the association between hyperuricemia and the risk for stroke and its subtypes. Subgroup analyses were conducted based on gender and age groups. Results: A total of 124 352 study subjects were included, with an accumulative follow-up time of 612 911.36 person-years. During the follow-up period, 4 638 cases of stroke were found, including 3 919 cases of ischemic stroke and 689 cases of hemorrhagic stroke. The incidence density of stroke was 756.72 per 100 000 person-years, 641.37 per 100 000 person-years for ischemic stroke, and 114.60 per 100 000 person-years for hemorrhagic stroke. Multivariable Cox proportional hazards regression models showed that after adjusting for covariates, compared to those without hyperuricemia, individuals with hyperuricemia had a 16% higher risk for stroke [hazard ratio (HR)=1.16, 95%CI: 1.06-1.27], a 12% higher risk of ischemic stroke (HR=1.12, 95%CI: 1.01-1.24), and a 39% higher risk of hemorrhagic stroke (HR=1.39, 95%CI: 1.11-1.75). Mediation analysis showed that hypertension partially mediated the associations between hyperuricemia and the risk for stroke, ischemic stroke, and hemorrhagic stroke, with mediation proportions of 36.07%, 39.98%, and 25.34%, respectively. The mediating effect is pronounced in the male population and individuals below 65. Conclusion: Hyperuricemia is a risk factor for stroke, and hypertension partially mediates the effect of hyperuricemia on stroke.