Yaohua Tian

Fine particulate air pollution and hospital visits for asthma in Beijing, China

Data on fine particulate matter (PM2.5) in China were first announced in 2013. The primary objective of this study was to evaluate the acute effects of PM2.5 on asthma morbidity in Beijing, China. A total of 978,658 asthma hospital visits consisting of 928,607 outpatient visits, 40,063 emergency room visits and 9988 hospital admissions from January 1, 2010, to June 30, 2012, were identified from the Beijing Medical Claim Data for Employees. A generalized additive Poisson model was applied to explore the association between PM2.5 and health service use. The mean daily PM2.5 concentration was 99.5 μg/m3 with a range from 7.2 μg/m3 to 492.8 μg/m3. Ambient PM2.5 concentration was significantly associated with increased use of asthma-related health services. Every 10 μg/m3 increase in PM2.5 concentration on the same day was significantly associated with a 0.67% (95% CI, 0.53%-0.81%), 0.65% (95% CI, 0.51%-0.80%), and 0.49% (95% CI, 0.35%-0.64%) increase in total hospital visits, outpatient visits and emergency room visits, respectively. The exposure-response association between PM2.5 concentration and hospital visits for asthma exacerbations was approximately linear. In conclusion, this study found that short-term elevations in PM2.5 concentration may increase the risk of asthma exacerbations. Our findings contribute to the limited scientific literature concerning the acute effects of PM2.5 on asthma morbidity outcomes in developing countries.

Fine Particulate Air Pollution and First Hospital Admissions for Ischemic Stroke in Beijing, China

The primary objective of this study was to assess the association between short-term changes in ambient fine particulate matter (PM2.5) and first hospital admissions for ischemic stroke. We identified 63,956 first hospital admissions for ischemic stroke from the Beijing Medical Claim Data for Employees from January 1, 2010, through June 30, 2012. A generalized additive Poisson model was applied to explore the association between PM2.5 and admissions for ischemic stroke. We also explore the effect modification of risk by age and gender. The exposure–response relationship between PM2.5 and admissions for ischemic stroke was approximately linear, with a relatively stable response at lower concentrations (<100 μg/m3) and a steeper response at higher concentrations. A 10 μg/m3 increase in the same-day PM2.5 concentration was associated with 0.31% (95% CI, 0.17–0.45%, P < 1.57 × 10−5) increase in the daily admissions for ischemic stroke. The association was also statistically significant at lag 1, 2, 3, 0–2 and 0–4 days. Subgroup analyses showed that the association was not different between patients ≥65 years and <65 years old or between males and females. In conclusion, short-term exposure to PM2.5 was positively associated with first hospital admissions for ischemic stroke in Beijing, China.

Ambient Particulate Matter Concentrations and Hospitalization for Stroke in 26 Chinese Cities

Background and Purpose— Little is known about the short-term health impacts of particulate matter (PM) on stroke in China. We, therefore, conducted a time-stratified case-crossover study to examine the association between ambient PM and hospital admissions for stroke in 26 Chinese cities. Methods— We identified hospital admissions for stroke by using electronic hospitalization summary reports from January 1, 2014 through December, 31 2015. We applied conditional logistic regression to explore the association between PM and hospital admissions for stroke. We also assessed the effect modification of stroke risk by geographical region, sex, and age. Results— Hospital admissions for ischemic (n=278 980) and hemorrhagic (69 399) strokes were examined separately. For ischemic stroke, both PM2.5 and PM10 had the strongest effect at lag 3 days, with an interquartile range increase in PM2.5 (47.5 &mgr;g/m3) and PM10 (76.9 &mgr;g/m3) significantly associated with a 1.0% (95% confidence interval, 0.7%–1.4%) and 0.8% (95% confidence interval, 0.3%–1.3%) increase in admissions for ischemic stroke, respectively. In northern China where PM pollution is more severe, the risk estimates for both PM2.5 and PM10 were larger than those in southern China in all lag structures. An interquartile range increase in PM2.5 and PM10 in northern China corresponded to a 1.0% (95% confidence interval, 0.7%–1.4%) and 0.7% (95% confidence interval, 0.3%–1.2%) increase in ischemic stroke admissions at lag 3 days, respectively. For hemorrhagic stroke, no significant association was observed with PM in the 26 cities. Conclusions— This study suggests that short-term elevations in PM may increase the risk of ischemic but not hemorrhagic stroke. The associations of PM with ischemic stroke are stronger in northern China than in the south.

Effect of Ambient Air Pollution on Hospitalization for Heart Failure in 26 of China's Largest Cities

There is growing interest in the association between ambient air pollution and congestive heart failure (CHF), but research data from developing countries are very limited. The primary aim of this study was to examine the association between short-term exposure to air pollution and hospital admission for CHF in China. A time-stratified case-crossover study was conducted between 2014 and 2015 in 26 large Chinese cities among 105,501 CHF hospitalizations. Conditional logistic regression models were applied to estimate the percentage changes in CHF admissions in relation to per interquartile range increases in air pollutant concentrations. Air pollution was positively associated with CHF hospitalizations. An interquartile range increase in fine particulate, particulate matter less than 10 µm in aerodynamic diameter, sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone concentrations on the current day corresponded to 1.2% (95% confidence interval [CI] 0.5%, 1.8%), 1.3% (95% CI 0.5%, 2.0%), 1.0% (95% CI 0.2%, 1.7%), 1.6% (95% CI 0.6%, 2.5%), 1.2% (95% CI 0.5%, 1.9%), and 0.4% (95% CI -0.9%, 1.7%) increases in CHF admissions, respectively. In conclusion, our findings contribute to the limited scientific literature concerning the effects of air pollution on CHF risk for high-exposure settings typical in developing countries, which may have significant public health implications for prevention of CHF in China.

Air Pollution and Hospitalization for Acute Myocardial Infarction in China.

There is growing interest in the association between ambient air pollution and acute myocardial infarction (AMI). The objective of this study was to explore the association in 14 Chinese cities using a time-stratified case-crossover design. We identified 80,787 hospital admissions for AMI between January 1, 2014 and December 31, 2015 from electronic hospitalization summary reports. Conditional logistic regression was used to estimate the percent changes with 95% confidence intervals (CIs) in AMI admissions in relation to an interquartile range increase in ambient air pollutant concentrations. All analyzed air pollutants, with the exception of ozone, were positively associated with daily AMI admissions on lag2 and lag3 days. An interquartile range increase in particulate matter <10 µm in aerodynamic diameter, sulfur dioxide, nitrogen dioxide, and carbon monoxide concentrations on lag2 day was significantly associated with a 0.8% (95% CI 0.1%, 1.6%), 2.0% (95% CI 1.2%, 2.9%), 2.2% (95% CI 1.4%, 3.1%), and 1.1% (95% CI 0.4%, 1.8%) increase in AMI admissions, respectively. We also observed a significant association in relation to ozone on lag4 day (percent change: 1.3%; 95% CI 0.2%, 2.4%). Subgroup analyses indicated no effect modification of risk by age (≥65 years and <65 years) or gender. In conclusion, this is the first multicity study in China, or even in other developing countries, to report the short-term effects of air pollution on AMI morbidity. Our findings contribute to the limited scientific data on the effects of ambient air pollution on AMI in developing countries.

Ambient air pollution and daily hospital admissions: A nationwide study in 218 Chinese cities

There have been few large multicity studies to evaluate the acute health effects of ambient air pollution on morbidity risk in developing counties. In this study, we examined the short-term associations of air pollution with daily hospital admissions in China. We conducted a nationwide time-series study in 218 Chinese cities between 2014 and 2016. Data on daily hospital admissions counts were obtained from the National Health Insurance Database for Urban Employees covering 0.28 billion enrollees. We used generalized additive model with Poisson regression to estimate the associations in each city, and we performed random-effects meta-analysis to pool the city-specific estimates. More than 60 million hospital admissions were analyzed in this study. At the national-average level, each 10 μg/m3 increase in PM10, SO2, and NO2, and 1 mg/m3 increase in CO at lag 0 day was associated with a 0.29% (95% CI, 0.23%-0.36%), 1.16% (95% CI, 0.92%-1.40%), 1.68% (95% CI, 1.40%-1.95%), and 2.59% (95% CI, 1.69%-3.50%) higher daily hospital admissions, respectively. The associations of air pollution with hospital admissions remained statistically significant at levels below the current Chinese Ambient Air Quality Standards. The effect estimates were larger in cities with lower air pollutants levels or higher air temperatures and relative humidity, as well as in the elderly. In conclusion, our findings provide robust evidence of increased hospital admissions in association with short-term exposure to ambient air pollution in China.

Real world adherence to oral anticoagulant in non-valvular atrial fibrillation patients in China

Abstract Background and objective: Adherence to oral anticoagulants is crucial for the prevention of ischemic stroke in atrial fibrillation patients; however, evidence of oral-anticoagulant adherence from developing countries is still lacking. This study aimed to evaluate the current situation and predictors of oral-anticoagulant adherence in non-valvular atrial fibrillation (NVAF) patients in China. Methods: Records of NVAF patients were obtained from a regional claims database. Both initiation and adherence to oral anticoagulants were calculated from linked records. Factors of oral-anticoagulant initiation were identified using Cox regression. Results: Among 33,463 NVAF patients, only 13.9% initialized warfarin treatment after the indexed hospital visit. Stratified by CHA2DS2-VASc scores, 20.9% of patients in the low-risk group were on warfarin, followed by 15.3% and 10.7% from the middle and high-risk groups, respectively. Among patients who initialized warfarin, only 40.4% filled the first repeat prescription within 3 months. Concurrent statin use, hypertension and heart failure were associated with higher warfarin initiation rate. Factors such as age above 75, female sex, manufacture workers, discharge from the primary-care center, antiplatelet use, and diabetes, ischemic and hemorrhagic stroke were associated with lower rate of warfarin initiation. Additionally, initiating warfarin treatment reduced risk of ischemic stroke in middle and high-risk patients. Conclusion: Oral anticoagulation was significantly under-used in NVAF patients in China. Age, sex, concurrent drug usage, and disease history were associated factors. Improving warfarin adherence was promising to reduce ischemic stroke risk of NVAF patients.

Short-term Effect of Ambient Ozone on Daily Emergency Room Visits in Beijing, China

Little is known about the acute effects of ozone on morbidity risk in China. We conducted a time-series study to examine the association between ozone and daily emergency room visits (ERVs) in Beijing, China. We identified 7,088,309 ERVs between January 1, 2014 and December 31, 2015. A generalized additive model with Poisson regression incorporating penalized spline functions was employed to analyze ERVs in association with daily 8-h maximum ozone concentrations. An increase of 10 μg/m3 of same-day ozone concentration was significantly associated with a 0.24% (95% CI, 0.21%–0.26%), 0.31% (95% CI, 0.27%–0.35%), and 0.43% (95% CI, 0.36%–0.50%) increase in daily ERVs for the whole study period, days when the daily 8-h maximum ozone met the Chinese Ambient Air Quality Standards (CAAQS) Grade II standard, and days that met the CAAQS Grade I standard, respectively. These results were robust when considering the potential confounding effects of PM2.5, PM10, NO2, SO2, and CO. In conclusion, our findings suggested significant effects of ozone exposure on daily ERVs in Beijing. Improving air quality with even lower ozone level than the current CAAQS could yield important public health.

Association of short-term exposure to ambient carbon monoxide with hospital admissions in China

Evidence on the acute effects of ambient carbon monoxide (CO) pollution on morbidity risk in developing countries is scarce and inconsistent. We conducted a multicity case-crossover study in 26 largest cities in China from January, 2014 to December, 2015 to examine the association between short-term exposure to CO and daily hospital admission. We fitted conditional logistic regression to obtain effect estimates of the associations. We also performed subset analyses to explore the health effects of CO at low levels. During the study period, a total of 14,569,622, 2,008,786 and 916,388 all-cause, cardiovascular and respiratory admissions were identified, respectively. A 1 mg/m3 increase in the CO concentrations corresponded to a 3.75% (95% CI, 3.63–3.87%), 4.39% (95% CI, 4.07–4.70%), and 4.44% (95% CI, 3.97–4.92%) increase in all-cause, cardiovascular, and respiratory admissions on the same day, respectively. The associations were robust to controlling for criteria co-pollutants. In subset analyses, negative effects of short-term CO exposure on hospital admission were observed at lower concentrations (<1 mg/m3), while positive effects were observed at higher concentrations (>2 mg/m3). In conclusion, current CO levels in China were significantly associated with increased daily hospital admissions.

Association between ambient air pollution and daily hospital admissions for ischemic stroke: A nationwide time-series analysis

Background Evidence of the short-term effects of ambient air pollution on the risk of ischemic stroke in low- and middle-income countries is limited and inconsistent. We aimed to examine the associations between air pollution and daily hospital admissions for ischemic stroke in China. Methods and findings We identified hospital admissions for ischemic stroke in 2014–2016 from the national database covering up to 0.28 billion people who received Urban Employee Basic Medical Insurance (UEBMI) in China. We examined the associations between air pollution and daily ischemic stroke admission using a two-stage method. Poisson time-series regression models were firstly fitted to estimate the effects of air pollution in each city. Random-effects meta-analyses were then conducted to combine the estimates. Meta-regression models were applied to explore potential effect modifiers. More than 2 million hospital admissions for ischemic stroke were identified in 172 cities in China. In single-pollutant models, increases of 10 μg/m3 in particulate matter with aerodynamic diameter <2.5 μm (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) and 1 mg/m3 in carbon monoxide (CO) concentrations were associated with 0.34% (95% confidence interval [CI], 0.20%–0.48%), 1.37% (1.05%–1.70%), 1.82% (1.45%–2.19%), 0.01% (−0.14%–0.16%), and 3.24% (2.05%–4.43%) increases in hospital admissions for ischemic stroke on the same day, respectively. SO2 and NO2 associations remained significant in two-pollutant models, but not PM2.5 and CO associations. The effect estimates were greater in cities with lower air pollutant levels and higher air temperatures, as well as in elderly subgroups. The main limitation of the present study was the unavailability of data on individual exposure to ambient air pollution. Conclusions As the first national study in China to systematically examine the associations between short-term exposure to ambient air pollution and ischemic stroke, our findings indicate that transient increase in air pollution levels may increase the risk of ischemic stroke, which may have significant public health implications for the reduction of ischemic stroke burden in China.