Road traffic noise and incident cardiovascular disease: a joint analysis of HUNT, EPIC-Oxford and UK Biobank

Background : Traffic noise has been associated with cardiovascular disease (CVD) in particular hypertension and ischemic heart disease (IHD), but evidence was not entirely consistent and population-based cohort studies on other CVD outcomes are lacking. Objectives : This study aimed to investigate the effects of long-term exposure to road traffic noise on incident CVD in three large cohorts. Methods : In a complete-case sample (N=361,699), 4,014 IHD and 2,109 cerebrovascular incident cases were ascertained between baseline periods 1993-2010 and end of follow-up 2008-2015 through medical record linkage. Annual mean road traffic noise exposure at baseline address was modelled for 2009 using a simplified version of the Common Noise Assessment Methods in Europe (CNOSSOS-EU). Individual-level data were harmonised and physically pooled across the three cohorts. Cox proportional hazard model was used for the analyses with adjustments for potential confounders, including air pollution. Results : For an interquartile range (IQR) (3.9 A-weighted dB) higher daytime noise, a non-significant association with incident IHD was seen for the overall population (Hazard ratio (HR): 1.015, 95% Confidence Interval (CI): 0.989-1.042), fully adjusted. The association was not confounded by air pollution. Statistically significant associations were seen among women (HR: 1.057, 95%CI: 1.012-1.103, P interaction : 0.346), those with a BMI ≥30kg/m 2 (HR: 1.099, 95%CI: 1.029-1.174, P interaction : 0.013), and current-smokers (HR: 1.054, 95%CI: 1.007-1.103, P interaction : 0.014). No associations were found for neither ischemic nor hemorrhagic stroke. Conclusions : Our study strengthens the evidence base of road traffic noise effects on incident IHD, whilst the association with incident stroke remains unclear and needs further investigations. 250