Contribution of metabolic factors as effect modifiers to the relationships between blood pressure components and stroke in Chinese rural adults: the Henan Rural Cohort Study

Background Although previous studies have explored the relationship between blood pressure (BP) component and stroke, it remains uncertain which BP component is best marker to identify stroke, especially in rural China. Furthermore, the role of metabolic factors in this association has not been reported. The aim of the study was to evaluate the efficiency of BP components as markers for identifying stroke in Chinese rural adults. Simultaneously, we quantified how much of the effects of BP on stroke were mediated through metabolic factors. Methods Of 38880 eligible individuals aged 18 to 79 were derived from the Henan Rural Cohort study. The relationships between BP components and stroke were explored by restricted cubic splines and logistic regression models. Receiver-operating characteristic curve was conducted to evaluate the identifying performance of BP components. Mediation analysis by bootstrap was used to explore the contribution of metabolic factors to BP - related stroke. Results In the fully models, the odds ratios (ORs) and 95% confidence intervals (95% CIs) of systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP) and mean arterial pressure (MAP) in the highest quartile with the risk of stroke were 1.81 (1.56-2.10), 1.72 (1.51-1.97), 1.55 (1.32-1.81) and 1.80 (1.57-2.06), respectively. The non-linear association tests demonstrated that the dose-response relationships were linear between SBP, DBP, PP and MAP with stroke (all p for non-linear > 0.05). In addition, PP had the largest area under curve value (0.655) for stroke in the crude model. However, MAP and SBP had the largest area under curve value (both 0.753) for identifying stroke after adjusting for potential confounders. We further reported that 3.51%–7.22% proportion explained risk of stroke was mediated through metabolic factors. Conclusions SBP and MAP might be better markers for identifying stroke than other BP components. In addition, BP -related stroke was mediated by some degree of metabolic factors.