Association of Ambient Particulate Matter Pollution of Different Sizes With In-Hospital Case Fatality Among Stroke Patients in China
Miao Cai, Shiyu Zhang, Xiaojun Lin, Zhengmin Qian, Stephen Edward McMillin, Yin Yang, Zilong Zhang, Jay Pan, Hualiang Lin
Abstract
<h3>Background and Objectives</h3> To characterize the association of ambient particulate matter (PM) pollution of different sizes (PM ≤1 µm in aerodynamic diameter [PM<sub>1</sub>], PM<sub>2.5</sub>, and PM<sub>10</sub>) with in-hospital case fatality among patients with stroke in China. <h3>Methods</h3> We collected hospitalizations due to stroke in 4 provinces in China from 2013 to 2019. Seven-day and annual averages of PM prior to hospitalization were estimated using bilinear interpolation and residential addresses. Associations with in-hospital case fatality were estimated using random-effects logistic regression models. Potential reducible fraction and the number of fatalities attributed to PM were estimated using a counterfactual approach. <h3>Results</h3> Among 3,109,634 stroke hospitalizations (mean age 67.23 years [SD 12.22]; 1,765,644 [56.78%] male), we identified 32,140 in-hospital stroke fatalities (case fatality rate 1.03%). Each 10 µg/m<sup>3</sup> increase in 7-day average (short-term) exposure to PM was associated with increased in-hospital case fatality: odds ratios (ORs) were 1.058 (95% CI 1.047–1.068) for PM<sub>1</sub>, 1.037 (95% CI 1.031–1.043) for PM<sub>2.5</sub>, and 1.025 (95% CI 1.021–1.029) for PM<sub>10</sub>. Similar but larger ORs were observed for annual averages (long-term): 1.240 (95% CI 1.217–1.265) for PM<sub>1</sub>, 1.105 (95% CI 1.094–1.116) for PM<sub>2.5</sub>, and 1.090 (95% CI 1.082–1.099) for PM<sub>10</sub>. In counterfactual analyses, PM<sub>10</sub> was associated with the largest potential reducible fraction in in-hospital case fatality (10% [95% CI 8.3–11.7] for short-term exposure and 21.1% [19.1%–23%] for long-term exposure), followed by PM<sub>1</sub> and PM<sub>2.5</sub>. <h3>Discussion</h3> PM pollution is a risk factor for in-hospital stroke-related deaths. Strategies that target reducing PM pollution may improve the health outcomes of patients with stroke.