New research from a large Nordic cohort study suggests that prolonged exposure to road and aircraft noise may elevate the risk of developing atrial fibrillation, particularly in women and individuals who are overweight or obese.
Study: Residential exposure to transportation noise and risk of incident atrial fibrillation: a pooled study of 11 prospective Nordic cohorts. Image Credit: MakDill/Shutterstock.com
In a recent study published in The Lancet Regional Health, a group of researchers investigated the association between residential exposure to transportation noise (road, railway, and aircraft) and the risk of developing atrial fibrillation (AF) (an irregular heart rhythm that increases the risk of stroke and heart complications) in a large pooled Nordic cohort.
Background
AF is the most common sustained cardiac arrhythmia, affecting about 4% of people over 50. Age, smoking, obesity, sleep apnea, and sedentary lifestyles are known risk factors, while environmental factors like traffic noise and air pollution have also been suggested as contributors.
Transportation noise, a global health issue, affects at least 20% of Europeans at levels above recommended limits. Studies link traffic noise with cardiometabolic diseases, but its association with AF remains unclear.
Further research is needed to clarify the inconsistent findings across studies and better understand the mechanisms linking transportation noise with AF risk.
About the study
The Nordic Studies on Occupational and Traffic Noise in Relation to Disease (NordSOUND) project, designed to assess the health impacts of occupational and traffic noise, included 11 cohort studies from Denmark, Sweden, and Finland. The data harmonization process ensured consistency across cohorts, following a predefined codebook.
The Danish cohorts included the nationwide Danish Nurse Cohort and the Diet, Cancer, and Health cohort. In contrast, the Swedish cohorts were located in Stockholm, Uppsala, Malmö, and Gothenburg and covered various population groups.
A Finnish cohort, Finnish National Risk Study (FINRISK), was also included. Address histories were available for participants, with annual updates in most Swedish cohorts and precise date records for Danish and Finnish cohorts.
AF was identified through linkage to national patient registers, which are known for their high validity. A diagnosis of AF before baseline led to participant exclusion, with incident AF defined based on national health coding systems.
Transportation noise exposure was estimated using sophisticated modeling techniques, accounting for noise from roads, railways, and aircraft at participants' residential addresses. These exposure estimates were calculated as time-weighted means over the previous one and five years.
The analysis adjusted for various confounders, such as demographics, lifestyle factors, and air pollution, to provide robust estimates of noise's impact on AF.
Study results
Out of the initial 179,966 participants from the original cohorts, 1,589 individuals with AF at baseline or earlier were excluded, along with 2,231 participants with missing exposure data and 15,031 with missing covariates. This resulted in a total of 161,115 participants in the final study cohort.
Over a median follow-up of 19.6 years, 18,939 new cases of AF were diagnosed. Baseline characteristics revealed that individuals exposed to higher road traffic noise (≥60 dB) were more likely to be single, smoke, and drink alcohol daily compared to those exposed to lower noise levels (<50 dB).
The average 5-year road traffic noise exposure at baseline ranged from 46.0 to 62.2 dB across the different cohorts, while railway noise levels were slightly lower, ranging between 46.3 and 53.1 dB.
Only a small proportion (1.8%) of participants were exposed to aircraft noise exceeding 50 dB. Additionally, baseline concentrations of particulate matter (PM2.5 ) were highest in the Danish cohorts, with levels between 19.8 and 20.9 μg/m3, whereas the Swedish and Finnish cohorts had lower concentrations (7.6-13.7 μg/m3).
Correlations between road traffic noise and other exposures were moderate, with the highest correlation observed between road traffic noise and Noteogen dioxide (NO2) (Spearman’s correlation coefficient: 0.49).
Road traffic noise was associated with a 2% increase in the risk of developing AF per 10 dB increase in 5-year mean exposure. Adjustments for individual lifestyle factors and particulate air pollution had little impact on the hazard ratios (HRs).
The results for 1-year mean road traffic noise exposure were consistent with those for 5-year exposure, with an HR of 1.02. A stronger association was observed when using a cut-off of 53 dB for road traffic noise, yielding an HR of 1.03 per 10 dB increase.
No clear association between railway noise and AF incidence was found, and no exposure-response relationship was observed. Similarly, for aircraft noise, there was no significant association, although some indication of increased risk was noted for exposure levels above 50 dB.
When examining exposure to multiple noise sources, the risk of AF increased with the number of noise sources participants were exposed to. Those exposed to all three sources, road, railway, and aircraft noise, had a 19% higher risk of developing AF than those with no elevated noise exposure.
Interaction analyses suggested stronger associations among females, individuals with higher body mass index (BMI), and former or current smokers, though these modifications were not always statistically significant.
Conclusions
To summarize, in the study, long-term exposure to residential road traffic noise and potentially aircraft noise was associated with a higher risk of developing AF.
Both exposures showed indications of an exposure-response relationship, and the associations remained after adjusting for sociodemographic, lifestyle factors, and air pollution.
No association was found between railway noise and AF, but higher HRs were observed with exposure to multiple noise sources. The associations were somewhat stronger among women and individuals with a BMI of 30 kg/m² or higher.
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