Association of air pollution with acute ischemic stroke risk in Singapore: a time-stratified case-crossover study

Abstract

Background: Air quality is an important determinant of cardiovascular health such as ischemic heart disease and acute ischemic stroke (AIS) with substantial mortality and morbidity reported across the globe. However, associations between air quality and AIS in the current literature remain inconsistent, with few studies undertaken in cosmopolitan cities located in the tropics. Objectives: We evaluated the associations between individual ambient air pollutants and AIS. Methods: We performed a nationwide, population-based, time-stratified case-crossover analysis on all AIS cases reported to the Singapore Stroke Registry from 2009 to 2018. We estimated the incidence rate ratio (IRR) of AIS across different concentrations of each pollutant by quartiles (referencing the 25th percentile), in single-pollutant conditional Poisson models adjusted for time-varying meteorological effects. We stratified our analysis by predetermined subgroups deemed at higher risk. Results: A total of 51,675 episodes of AIS were included. Ozone (O3) (IRR4th quartile: 1.05, 95% confidence interval (CI): 1.01–1.08) and carbon monoxide (CO) (IRR2nd quartile: 1.05, 95% CI: 1.02–1.08, IRR3rd quartile: 1.07, 95% CI: 1.04–1.10, IRR4th quartile: 1.07, 95% CI: 1.04–1.11) were positively associated with AIS incidence. The increased incidence of AIS due to O3 and CO persisted for 5 days after exposure. Those under 65 years of age were more likely to experience AIS when exposed to CO. Individuals with atrial fibrillation (AF) were more susceptible to exposure from O3, CO, and PM10. Current/ex-smokers were more vulnerable to the effect of O3. Conclusion: Air pollution increases the incidence of AIS, especially in those with AF and in those who are current or ex-smokers.

Application of smart devices in investigating the effects of air pollution on atrial fibrillation onset

“…Meanwhile, air pollution could also cause immediate respiratory abnormalities (such as airway spasm and inflammation) 27 , increasing pulmonary artery pressure and elevating right atrial pressure, which might also induce AF episodes. Furthermore, as cardiac arrhythmia is a major pathway in the development of cardiovascular diseases, findings of this study could provide mechanistic insights for the previous studies that linked air pollution with the risk of other cardiovascular disorders, such as stroke and sudden cardiac arrest [28][29][30] . Notably, we did not find an association between O 3 and AF, which is contrary to some existing findings 15 .…”

Climate change and population health in Singapore: a systematic review

“…Findings from this study highlight the importance of understanding the temperature dependency of vector-borne diseases in resource planning for an anticipated climate change scenario. 9 Association of air pollution with acute ischemic stroke risk in Singapore: a time-stratified case-crossover study 37 Ho et al. (2022) Time-stratified case-crossover study; 2009–2018; National-level Air pollution increases the incidence of acute ischemic stroke, especially in those with atrial fibrillation and in those who are current or ex-smokers.…”

The global impact of stroke in 2022

“…[7][8][9] Further evidence of this association is provided in a paper by Ho et al in this issue. 10 They performed a nationwide population-based analysis of all ischaemic stroke cases reported to the Singapore Stroke Registry between 2009 and 2018. Using this, they estimated the incidence rate ratio of ischaemic stroke across different concentrations of different pollutants.…”