A Meta-analysis Of The Correlation Between Short-term Exposure To Major Air Pollutants And The Incidence Of Ischemic Stroke

Objective:To quantitatively evaluate the relationship between short-term exposure to major air pollutants and the incidence of ischemic stroke by using the Meta-analysis.Methods:Chinese key words"ischemic stroke,cerebral infarction,air pollution,particulate matter,carbon monoxide,sulfur dioxide,nitrogen dioxide,ozone"and English key words"ischemic stroke,air pollution"are used as subject words.A systematic search was made for literatures related to major air pollutants and ischemic stroke published by February 1,2021 in Chinese databases such as China Journal Fulltext Database and Chinese Biomedical Literature Database,and foreign databases such as Pub Med,Cochrane library,Web of Science,and Embase.Stata/SE version 16.0was used to conduct Meta-analysis step by step through the procedures of heterogeneity test,combined effect size,Meta-regression,subgroup analysis,sensitivity analysis and publication bias test.Results:1.A total of 2224 articles were retrieved.According to the inclusion and exclusion criteria,32 articles were included（1 in Chinese and 31 in English）.The total number of people included in the literature is 7071334;2.PM₁₀ and CO groups studies showed homogeneity,and fixed effects model was used to combine effects.PM_2.5,NO₂,SO₂,and O₃ groups showed moderate to high heterogeneity,and random effects model was used to combine effect sizes.Meta-analysis results showed that PM_2.5[OR=1.0090（95%CI:1.0053～1.0128）,P=0.000],PM₁₀[OR=1.0017（1.0008～1.0026）,P=0.000],CO[OR=1.0328（95%CI:1.0231～1.0426）,P=0.000],NO₂[OR=1.0150（95%CI:1.0079～1.0222）,P=0.000],SO₂[OR=1.0138（95%C I:1.0239～1.0222）,P=0.000],and O₃[OR=1.0018（95%CI:1.0001～1.0036）,P=0.041]were associated with an increased risk of IS;3.From the day of onset to 5 days before onset of ischemic stroke,except for the combined effect value of PM₁₀ in lag0[OR=1.0018（95%CI:1.0007～1.0029）]and lag1[OR=1.0011（95%CI:1.0001～1.0021）],the other 5 pollutants only showed an increased risk of IS caused by short-term exposure to pollutants at lag0[PM_2.5:OR=1.0078（95%CI:1.0043～1.0112）,CO:OR=1.0320（95%CI:1.0223～1.0418）,NO₂:OR=1.0140（95%CI:1.0075～1.0204）,SO₂:OR=1.0126（95%CI:1.0048～1.0205）,O₃:OR=1.0010（95%CI:1.0001～1.0019）];4.Subgroup analysis based on season showed that the combined effect value of the cold season subcombination in the PM_2.5 group and the combined effect value of the warm season in the NO₂ and SO₂ group were statistically significant;5.The literature of PM_2.5,PM₁₀,CO,NO₂,SO₂ groups all show large sample size sub-combinations and the effect value is statistically significant.Conclusions:1.Short-term exposure to PM_2.5,PM₁₀,CO,NO₂,SO₂ and O₃ was positively correlated with the incidence of IS in the population,and the effect of this risk was most significant on the day of the onset;2.The impact of short-term exposure to PM_2.5 on the onset of IS is more significant in the cold season,and the impact of short-term exposure to NO₂and SO₂ on the onset of IS is more significant in the warm season;3.Compared with small sample size researches,large sample size researches are more likely to draw conclusions that short-term air pollution exposure is related to the incidence of IS;4.No significant differences in the health effects of air pollution caused by factors such as different research methods and research areas have been found.