Metabolic Syndrome and Its Mediation Effects of Fine Particulate Matter and Cardiovascular Disease

Background / AimsConsiderable epidemiological evidence indicates particulate matter (PM) as a major risk factor for cardiovascular diseases (CVD). Also, Metabolic syndrome (MetS) is well known as an important risk factor for CVD and a few studies show epidemiological association between PM and MetS. However, a study on the effect of PM on CVD as a mediator of MetS is still scarce. Thus, we examined a mediation of the association between PM2.5 and CVD by MetS.Methods / ResultsParticipants of this study were 153,417 adults from the national health screening cohort provided by Korea National Health Insurance who had health examination from 2009 to 2015. MetS was defined by National Cholesterol Education Program the third Adult Treatment Panel and exposure to PM2.5, one-year average before CVD diagnostic, was assessed using a Community Multiscale Air Quality (CMAQ) model. To determine whether MetS is a mediator variable and to quantify the mediation effect, we conduct a counterfactual mediation analyses. The effect estimates (natural direct effect (NDE), natural indirect effect (NIE), and total effect) with 1- increase in one-year average PM2.5 concentration and the percentage of the effect of mediator were calculated by logistic regression models. Also, 95% confidence interval (CI) were obtained from bootstrap method. Results from adjusted mediation analyses showed that the mediation was significant for the association between PM2.5 and CVD (NIE: 1.001, 95% CI: 1.000 – 1.002). In addition, the percent of the total effect mediated by MetS was 13% (p-value: 0.04), in reference to a total adjusted odds ratio of 1.010 (95% CI: 1.005 – 1.013).ConclusionOur findings suggest that MetS might appear as a mediate on the association between PM2.5 and CVD. These results highlight the need of a further study to clarify that exposure to one-year average PM2.5 is associated with an increased risk of CVD mediated by MetS.