Geographical variation and mediation analysis of incidence in stroke: Insights from CHARLS cohort study

IntroductionStroke is leading cause of mortality in China and it has regional disparities in the incidence among Chinse populations. The study aimed to investigate whether and how much of the association between regional disparities and stroke is explained by an mediator. MethodsWe applied Cox proportional hazard regression model and mediation analysis to analyse results from the follow-up of of the CHARLS database. ResultsOver the median follow-up of 9.8 years in CHARLS, 5.1 (%) of CHARLS participants developed a stroke. We found that North China had the highest incidence of stroke, followed by Central, Northeast, Northwest, Eastern, and Southwest China. South China had the lowest incidence of stroke, and was the reference group. Rural residents who were older and smokers had a higher risk of stroke. Subgroup analysis revealed that the incidence of stroke in Northeast China was significantly higher among female urban residents with lower education levels, diabetes, and hypertension. The mediation analysis showed that hypertension had a significant mediation effect in Northeast, North, and Northwest China. Dyslipidemia had similar mediating effect in the Northwest and North China, but not in other regions. ConclusionGeographical variation is associated with a different incidence of stroke. This association is partially mediated by hypertension in Northern, Northeastern, and Northwestern China, and by dyslipidemia in Northwestern and Northern China.