Interactive effects of outdoor fine particulate matter and metabolic, behavioural, and psychosocial risk factors on cardiovascular disease: analysis of the PURE-China cohort study
Authors: Hao J , Liu Z , Hu B , Tse L A , Rangarajan S , Wang C , Wang Y , Liu W , Li S , Wang D , Yusuf S , Li W 
Published: October 2024

Abstract

Background
Long-term PM2.5 exposure has been associated with an elevated risk of cardiovascular disease (CVD) and its associated risk factors.[1–4] There is a paucity of studies investigating the interactive effects of PM2.5 exposure and a comprehensive list of risk factors including metabolic, behavioural, and psychosocial risk factors on CVD risk.[5]

Purpose
This study aims to examine the interactive effects of PM2.5 exposure and metabolic, behavioural, and psychosocial risk factors on incident CVD.

Methods
The Prospective Urban Rural Epidemiology (PURE)-China cohort study is a population-based cohort study recruiting participants aged 35–70 years from 115 communities in 12 provinces of China between 2005 and 2009, and followed up until August 31, 2021.[6] Participants’ metabolic, behavioural, and psychosocial risk factor information was recorded. PM2.5 concentrations were extracted from a 1x1 km2 global model.[7,8] For this analysis, we included participants aged 35–70 years at baseline without a history of CVD, with at least one follow-up visit. The primary outcome was a composite of major cardiovascular events (CVD deaths, myocardial infarction, stroke, and heart failure). Additive interaction was measured by relative excess risk due to interaction (RERI), the proportion of disease attributable to interaction (AP), and the synergy index (SI).[9,10] To comply with the additive interaction method, we classified concentrations of PM2.5 into low and high levels by the median of 3-year average PM2.5 concentration (45.7 μg/m3, IQR: 33.7-74). Cox proportional hazard models were used to assess the associations of metabolic, behavioural, and psychosocial risk factors on incident CVD by PM2.5 concentrations.

Results
The PURE-China study recruited 47 931 participants, of which 39 329 are eligible for this analysis. During the median follow-up period of 11.9 years (IQR: 9.6-12.6), 1462 and 2155 major CVD events had occurred in the low and high PM2.5 group respectively. There was a synergistic interaction between PM2.5 and the systolic blood pressure (SBP) for CVD: RERI: 0.363, 95% CI: 0.196-0.531; AP: 0.098, 95% CI: 0.081-0.115; SI: 1.155, 95% CI: 1.132-1.177; high LDL cholesterol: RERI: 0.219, 0.003-0.436; AP: 0.135, 0.008-0.263; SI: 1.549, 0.947-2.533. A significant synergistic interaction was also identified between PM2.5 and household air pollution (RERI: 0.457, 0.292-0.622; AP: 0.277, 0.184-0.37; SI: 3.362, 1.409-8.019). Interactions between PM2.5 and low grip strength on CVD were significantly synergistic, but antagonistic between PM2.5 and low physical activity (RERI: -0.248, -0.485--0.012; AP: -0.174, -0.349-0.001; SI: 0.633, 0.412-0.971).

Conclusion
Addictive interaction was between PM2.5 and SBP, high LDL cholesterol, household air pollution, low grip strength and low physical activity on incident CVD, indicating the benefit of coordinated control strategies for metabolic, physical, and environmental risk factors for the prevention of CVD.