Effects of ambient carbon monoxide on daily hospitalizations for cardiovascular disease: a time-stratified case-crossover study of 460,938 cases in Beijing, China from 2013 to 2017

Xia Li,Yanxia Luo,Anxin Wang,Tianqi Wang,Endawoke Amsalu,Qi Gao,Jin Guo,Jingwei Wu,Wei Wang,Songxi Chen,Yuming Guo,Xinghua Yang,Xiuhua Guo,Haibin Li

doi:10.1186/s12940-018-0429-3

Abstract

BackgroundEvidence focused on exposure to ambient carbon monoxide (CO) and the risk of hospitalizations for cardiovascular diseases (CVD) is lacking in developing countries. This study aimed to examine the effect of CO exposure on hospitalizations for CVD in Beijing, China.MethodsA total of 460,938 hospitalizations for cardiovascular diseases were obtained from electronic hospitalization summary reports from 2013 to 2017. A time-stratified case-crossover design was conducted to investigate the association between CO exposure and hospitalizations for total and cause-specific CVD, including coronary heart disease (CHD), atrial fibrillation (AF), and heart failure (HF). Stratified analysis was also conducted by age group (18–64 years and ≥ 65 years) and sex.ResultsLinear exposure-response curves for the association between ambient CO exposure and hospitalizations for CVD was observed. Ambient CO was positively associated with hospitalizations for total CVD and CHD. However, the observed increased risk was not statistically significant for hospitalizations for AF and HF. The strongest effect of CO concentration was observed on the current- and previous-day of exposure (lag 0–1 day). For a 1 mg/m3 increase in a 2-day moving average CO concentration, an increase of 2.8% [95% confidence interval (CI): 2.2 to 3.3%] and 3.0% (95% CI: 2.4 to 3.6%) in daily hospital admissions for CVD and CHD were estimated, respectively. This association was robust after adjusting for other copollutants and did not vary by age group and sex.ConclusionsAmbient CO exposure increased the risk of hospitalizations for CVD, especially for CHD in Beijing. Further studies are warranted to explore the association between ambient CO and hospitalizations for AF and HF.

Highlights

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide [1]
We reported the percentage changes (PC% = [relative risk (RR)-1] × 100%) in daily hospital admissions for cardiovascular diseases (CVD) per 1 mg/m3 increase of carbon monoxide (CO) concentrations and its corresponding 95% confidence interval (CI)
In the single pollutant model, for a 1 mg/m3 increase in the 2-day moving average CO concentrations, we observed significant increases of 2.8% in the daily hospital admission for CVD, 3.0% for coronary heart disease (CHD), 1.4% for atrial fibrillation (AF) and 1.2% (− 0.4 to 2.7%) for heart failure (HF)

Summary

Introduction

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide [1]. Meta-analysis and epidemiological studies have reported that air pollution increased the risk of morbidity and mortality due to CVD [3,4,5,6,7]. Liu and colleagues conducted a nationwide time-series analysis in 272 major cities in China and found that ambient carbon monoxide (CO) exposure caused a 1.1% (95% confidence interval: 0.4 to 1.8%) increase in the risk of cardiovascular disease mortality per 1 mg/m3 increment [7]. Koken, et al reported a significant association between short-term exposure to ambient CO and hospitalizations for CVD among elderly individuals in Denver [8]. This study aimed to examine the effect of CO exposure on hospitalizations for CVD in Beijing, China

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