Impacts of Ambient Carbon Monoxide on Hospital Admissions and Hospitalization Expenditures for Three Cardiorespiratory Diseases in 74 Cities of China

BACKGROUND AND AIM: Evidence about health burden and economic loss of cardiorespiratory diseases (CRDs) caused by ambient carbon monoxide (CO) is sparse. We aimed to assess health burden as well as economic loss caused by coronary heart disease (CHD), stroke and lower respiratory infections (LRI) attributed to ambient CO in multiple cities in China. METHODS: Hospital admission and expenditures data were obtained from urban employee-based basic medical insurance scheme (UEBMI) of the national health insurance system in China. We performed a three-stage time-series analysis approach based on Generalized Linear Model controlling for potential confounding factors to examine the association between ambient CO and hospitalization data of CHD, stroke and LRI in 74 cities of China from January 1, 2015 to December 31, 2017. We conducted subgroup analyses by geographical region, gender and age (15-64 and ≥65), and tested the robustness of the results in two-pollutant models and sensitive analyses. RESULTS:We found that the average daily concentration of ambient CO across 74 cities from 2015 to 2017 was 1.10 mg/m³ (SD: 0.62). For a 1 mg/m³ increase in CO concentrations, the largest excess risks (ERs) were 3.82% (95% CI: 1.27% to 6.44%) at lag04 for CHD, 3.14% (95% CI: 1.90% to 4.38%) at lag0 for stroke and 2.71% (95% CI: 1.21% to 4.23%) at lag01 for LRI. Moreover, we observed that 4.50%, 3.33% and 2.97% of CHD, stroke and LRI related hospital admissions during 2015 to 2017 could be attributed to ambient CO in included cities, and the annualized attributable numbers of hospitalization expenditures were enormous, with 490 million CNY (US$ 73 M), 371 million CNY (US$ 55 M) and 217 million CNY (US$ 32 M) for CHD, stroke and LRI, respectively. CONCLUSIONS:Our study provides robust evidence for substantial excess hospitalization burden of CHD, stroke and LRI attributable to ambient CO based on multi-city analyses. KEYWORDS: Air pollution, Cardiovascular diseases, Environmental epidemiology, Traffic-related, Respiratory outcomes