Time-stratified Case-crossover Study Design Research Articles

Airborne pollen exposure and risk of hospital admission for allergic rhinitis in Beijing: A time-stratified case-crossover study.

Airborne pollen is a crucial risk factor in allergic rhinitis (AR). The severity of AR symptoms can vary based on pollen type and concentration. This study aimed to estimate the association between exposure to different pollen types and AR risk. We obtained data from patients admitted to the Beijing Tongren Hospital for AR, and data on pollen concentration, meteorological factors, and fine particulate matter (PM2.5) from 13 districts in Beijing from 2016 to 2019. We used a time-stratified case-crossover study design and calculated odds ratios (ORs) related to the risk of AR associated with a 10 grain/1000mm2 increase in total pollen concentrations for specific pollen types. A stratified analysis was conducted to assess whether the associations were varied by age and sex. The OR of AR associated with a 10 grain/1000mm2 increase in the 7-day average pollen concentration was 1.014 (95% CI: 1.014, 1.015), 1.076 (95% CI: 1.070, 1.082), 1.024 (95% CI: 1.023, 1.025), 1.042 (95% CI: 1.039, 1.045), 1.142 (95% CI: 1.137, 1.147), 1.092 (95% CI: 1.088, 1.097), 1.046 (95% CI: 1.035, 1.058), and 1.026 (95% CI: 1.024, 1.028) for total pollen, Ulmus, Cupressaceae, Populus, Fraxinus, Pinus, Betula, and Artemisia, respectively. Both tree pollen (Ulmus, Cupressaceae, Populus, Fraxinus, Betula, and Pinus) and weed pollen (Artemisia, Chenopodium, and Humulus) were correlated with an increased risk of AR. These associations remained consistent across distinct subgroups defined by both age and sex. Exposure to pollen from trees and weeds might be associated with an increased risk of AR. This research provides valuable scientific support for both clinical practitioners and patients with AR regarding the hazards of pollen exposure.

Associations between air pollution and the onset of acute exacerbations of chronic obstructive pulmonary disease: A time-stratified case-crossover study in China

Associations between air pollution and the acute exacerbations of chronic obstructive pulmonary disease (AECOPD) have been established primarily in time-series studies in which exposure and case data were at the aggregate level, limiting the identification of susceptible populations. Are air pollutants associated with the onset of AECOPD in China? Who is more susceptible to the effects of air pollutants? AECOPD data were obtained from the Acute Exacerbation of Chronic Obstructive Pulmonary Disease Registry study and air pollution data were assigned to individuals based on their residential address. We adopted a time-stratified case-crossover study design combined with conditional logistic regression models to estimate the associations between six air pollutants and AECOPD. Stratified analyses were performed by individual characteristics, disease severity, COPD types, and the season of exacerbations. A total of 5,746 patients were finally included. At a 2-day lag, for each interquartile range increase in PM2.5 and PM10 concentrations, odds ratios for AECOPD were 1.054 (95% CI: 1.012, 1.097) and 1.050 (95% CI: 1.009, 1.092), respectively. The associations were more pronounced in participants who were aged < 65 years, had experienced at least one severe AECOPD in the past year, were first diagnosed with COPD between the ages of 20 and 50, and experienced AECOPD in the cool seasons. By contrast, significant associations for NO2, SO2, and CO lost significance when excluding cases collected before 2020 or with larger distance from the monitoring station, and no significant association was observed for O3. This study provides robust evidence that short-term exposure to PM2.5 and PM10 was associated with higher odds of AECOPD onset. Individuals who are young, have severe COPD or young COPD, and experience an exacerbation during the cooler seasons may be particularly susceptible. NCT2657525 (ClinicalTrials.gov).

Effects of Coexposure to Air Pollution from Vegetation Fires and Extreme Heat on Mortality in Upper Northern Thailand.

Background: understanding the effects of coexposure to compound extreme events, such as air pollution and extreme heat, is important for reducing current and future health burdens. This study investigated the independent and synergistic effects of exposure to air pollution from vegetation fires and extreme heat on all-cause mortality in Upper Northern Thailand. Methods: we used a time-stratified case-crossover study design with a conditional quasi-Poisson model to examine the association between mortality and coexposure to air pollution due to vegetation fire events (fire-PM2.5) and extreme heat. Extreme heat days were defined using the 90th and 99th percentile thresholds for daily maximum temperature. Results: we observed a significant positive excess risk of mortality due to independent exposure to fire-PM2.5 and extreme heat, but not an interactive effect. All-cause mortality risk increased by 0.9% (95% confidence interval (CI): 0.1, 1.8) for each 10 μg/m3 increase in fire-PM2.5 on the same day and by 12.8% (95% CI: 10.5, 15.1) on extreme heat days (90th percentile) relative to nonextreme heat days. Conclusion: this study showed that exposure to PM2.5 from vegetation fires and extreme heat independently increased all-cause mortality risk in UNT. However, there was no evidence of a synergistic effect of these events.

P1105 Short-term exposure to environmental air pollution and inflammatory bowel disease flares: a time-stratified case cross-over study

Abstract Background Some epidemiological studies suggest that long-term exposure to environmental air pollutants, such as particulate matter (PM), could have a role in inflammatory bowel disease (IBD) incidence and pathogenesis. However, less is known about the potential effect of short-term air pollution exposure. The aim of this study is to investigate whether short-term exposure to environmental air pollution is associated with the occurrence of IBD flares. Methods Anonymized hospital discharge records (HDR) with ICD-9-CM codes 555 (Crohn’s disease) and 556 (ulcerative colitis) for years 2002-2009 from all hospitals of the Lombardy region were collected. All HDR of adult patients (18-75 years) resident in Milan were included, except for recurrent hospitalizations within 6 months. Each record was assigned daily PM ≤10 µm (PM10) concentrations at municipality level by averaging PM10 levels of the day of admission with the levels of the day before (lag01) and of each preceding day up to six days before (lag06). To evaluate the association between PM10 and IBD-related hospitalizations, a time-stratified case-crossover study design was applied. Conditional logistic regression models, calculating Odds Ratios (OR) and 95% Confidence Intervals (95%CI) per increments of 10 µg/m3 of PM10, were performed. Results Overall, 2,176 hospital admissions (males=1,137, Crohn’s disease=1,264, ulcerative colitis=912) were included. In the entire population no clear association between PM10 and IBD-related hospitalization was identified, notwithstanding a small risk increase for males (OR: 1.03; 95%CI: 0.99-1.08 at lag04). When further stratifying for ICD code, an increased risk of hospitalization for "left-sided ulcerative colitis" (ICD code: 556.5) was found in males only, for exposures in all days preceding hospitalization up to lag04 (1.28; 1.05-1.28; 59 cases, 207 controls) (Figure 1). In females, the association was weaker, although positive (1.14; 0.91-1.42; 49 cases, 164 controls). No relevant findings emerged when looking at other ICD codes. Conclusion We observed an increased risk of IBD-related hospitalization in male patients with left-sided ulcerative colitis per increasing levels of air pollution in the days preceding hospital admission. Although preliminary, our findings suggest the possible role of sex as an effect modifier of the influence that air pollution might exert on IBD flares. Further studies are needed to better comprehend the complex framework characterizing the interplay between environmental and individual factors contributing to IBD.

Short-term exposure to ambient air pollution and injuries due to external causes according to intentions and mechanisms

Although injuries are a leading cause of death and affect the life expectancy of individuals who live with disabilities globally, the potential role of air pollution exposure on injuries due to external causes has received little scientific attention, especially compared with that given to the association of air pollution and non-external causes of morbidity and mortality. We investigated the association between emergency department visits for externally caused injuries and short-term exposure to major ambient air pollutants, with focus on the intentions and mechanisms of injuries. We identified 2,049,855 injured patients in Seoul, South Korea between 2008 and 2016 using the National Emergency Database. Daily short-term exposure to air pollution including particles <10 μm (PM10) and <2.5 μm (PM2.5), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3) was estimated based on hourly concentrations. We employed a time-stratified case-crossover study design using a conditional Poisson regression model adjusted for meteorological variables, influenza epidemics, and holidays. Immediate exposure (lag 0) to most pollutants significantly increased the risk of total injuries (PM2.5, 0.42 %; NO2, 0.68 %; SO2, 1.05 %; CO, 0.57 %; O3, 1.86 % per interquartile range increment), and the associations differed according to the intention and mechanism of injury. Unintentional and assault injuries were significantly associated with air pollution exposure, whereas self-harm injuries showed no association. In mechanism-specific analyses, injuries caused by falls, blunt objects, penetration, traffic accidents, machinery, and slips were associated with specific air pollutants, even in the co-pollutant models. The associations were stronger in injured patients aged <15 years, and in males than in their counterparts. Our results suggest that short-term air pollution exposure might play a role in the risk of externally caused injuries and the association may differ depending on the intention and mechanism of injury, which provide important evidence for injury prevention and air quality strategies.

Impacts of short-term low-level exposure to air pollutants on hospital admissions for pulmonary sepsis in elderly patients

BackgroundAcute exposures to high levels of air pollutants are thought to be associated with hospitalization of patients with lung infection, while relatively little is known about the association between air pollutants and HOSPITAL ADMISSIONS FOR pulmonary sepsis.ObjectivesTo assess the correlation between low-level exposure to air pollutants and the hospitalizations for pulmonary sepsis in elderly patients.MethodsA total of 249 elderly patients with pulmonary sepsis from January 2018 to December 2020 in Shenzhen people’s hospital were included. The data regarding hospitalizations for pulmonary sepsis, meteorological factors, and daily average levels of air pollutants on single-day lags (Lag0 to Lag7) in Shenzhen were collected. Low-level exposure was defined as the annual means of air pollutants below the levels of the Ambient Air Quality Standard (AAQS) in China (NO. GB3095-2012) and/or Global Air Quality Guidelines (AQG). A time-stratified case-crossover study design approach was used to evaluate the associations between exposure to air pollutants and incidence of the disease, univariate and multivariate logistic regression analysis to analyze the association between levels of air pollutants and hospitalizations for pulmonary sepsis in elderly patients.ResultsExposure to PM1(P = 0.007, Lag 2 day; P = 0.038, Lag6 day), PM2.5(P = 0.046, Lag2 day), PM10(P = 0.048, Lag4 day), and O3(P = 0.044, Lag6 day) was positively correlated with elevated risk of hospitalizations for pulmonary sepsis. In addition, logistic regression analysis revealed that exposure to PM1 (OR = 1.833, 95%CI:1.032 ~ 3.256, Lag6 day) and O3 (OR = 2.091, 95%CI:1.019 ~ 4.289, Lag6 day) were the independent risk factors of pulmonary sepsis in elderly patients.ConclusionOur results demonstrate that short-term low-level exposure to PM1 and O3 could elevate the risk of hospitalizations for pulmonary sepsis in elderly patients in Shenzhen, providing evidence for developing early warning and screening systems for pulmonary sepsis.

The joint associations of ambient air pollutants and weather factors with mortality: Evidence from a national time-stratified case-crossover study in China

BackgroundPeople in daily life are usually exposed to multiple environmental factors, but few studies have evaluated the joint health impacts of ambient air pollutants and weather factors. ObjectivesTo investigate the joint associations of short-term exposures to ambient air pollutants and weather factors with mortality and estimate the mortality burden attributable to these multiple environmental exposures in China. MethodsWe collected individual death information from six provinces (Guangdong, Yunnan, Hunan, Zhejiang, Tibet and Jilin) in China during 2013 to 2018, and applied a time-stratified case-crossover study design to estimate the joint associations of air pollutants [PM2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm), O3 (ozone), NO2 (nitrogen dioxide), SO2 (sulfur dioxide), and CO (carbon monoxide)] and weather factors (temperature and relative humidity) with mortality. Air pollutant concentrations on the case day and control days were assessed using a random forest model, and the corresponding temperature and relative humidity data were assessed using a thin plate smoothing model. Excess risks (ER) of exposure to air pollutants and weather factors were estimated using Cox proportional regression models and the attributable fraction (AF) was calculated. ResultsA total of 6,685,146 deaths were enrolled in this study. The overall AF of total mortality attributed to air pollutants (lag03 days) and weather factors (lag021 days) was 16.65 % (95%CI: 16.43 %, 16.87 %), in which the joint AFs attributable to air pollutants and weather factors were 5.31 % (95%CI: 5.08 %, 5.53 %) and 11.34 % (95%CI: 11.12 %, 11.56 %) respectively, and temperature contributed 56 % in the joint effects. Stratified analyses showed greater AFs in females (21.32 %) than in males (14.61 %), and in the elderly (>100 years, 42.34 %) than in young people (21–30 years, 7.67 %). The AFs of mortality from cardiovascular diseases, respiratory diseases, and pneumonia attributed to the joint exposures were 22.72 %, 24.82 % and 33.03 %, respectively. DiscussionThis study provides the joint associations of short-term exposures to both air pollutants and weather factors with mortality risk in China, which has important implications in comprehensively assessing the health impacts of environmental exposures, and taking actions to protect human health.

Short-term exposure to PM2.5 and 1.5 million deaths: a time-stratified case-crossover analysis in the Mexico City Metropolitan Area

BackgroundSatellite-based PM2.5 predictions are being used to advance exposure science and air-pollution epidemiology in developed countries; including emerging evidence about the impacts of PM2.5 on acute health outcomes beyond the cardiovascular and respiratory systems, and the potential modifying effects from individual-level factors in these associations. Research on these topics is lacking in low and middle income countries. We aimed to explore the association between short-term exposure to PM2.5 with broad-category and cause-specific mortality outcomes in the Mexico City Metropolitan Area (MCMA), and potential effect modification by age, sex, and SES characteristics in such associations.MethodsWe used a time-stratified case-crossover study design with 1,479,950 non-accidental deaths from the MCMA for the period of 2004–2019. Daily 1 × 1 km PM2.5 (median = 23.4 μg/m3; IQR = 13.6 μg/m3) estimates from our satellite-based regional model were employed for exposure assessment at the sub-municipality level. Associations between PM2.5 with broad-category (organ-system) and cause-specific mortality outcomes were estimated with distributed lag conditional logistic models. We also fit models stratifying by potential individual-level effect modifiers including; age, sex, and individual SES-related characteristics namely: education, health insurance coverage, and job categories. Odds ratios were converted into percent increase for ease of interpretation.ResultsPM2.5 exposure was associated with broad-category mortality outcomes, including all non-accidental, cardiovascular, cerebrovascular, respiratory, and digestive mortality. A 10-μg/m3 PM2.5 higher cumulative exposure over one week (lag06) was associated with higher cause-specific mortality outcomes including hypertensive disease [2.28% (95%CI: 0.26%–4.33%)], acute ischemic heart disease [1.61% (95%CI: 0.59%–2.64%)], other forms of heart disease [2.39% (95%CI: -0.35%–5.20%)], hemorrhagic stroke [3.63% (95%CI: 0.79%–6.55%)], influenza and pneumonia [4.91% (95%CI: 2.84%–7.02%)], chronic respiratory disease [2.49% (95%CI: 0.71%–4.31%)], diseases of the liver [1.85% (95%CI: 0.31%–3.41%)], and renal failure [3.48% (95%CI: 0.79%–6.24%)]. No differences in effect size of associations were observed between age, sex and SES strata.ConclusionsExposure to PM2.5 was associated with non-accidental, broad-category and cause-specific mortality outcomes beyond the cardiovascular and respiratory systems, including specific death-causes from the digestive and genitourinary systems, with no indication of effect modification by individual-level characteristics.

Assessing the Effect of Precipitation on Asthma Emergency Department Visits in New York State From 2005 to 2014: A Case-Crossover Study.

The Earth's precipitation patterns are changing, and regional precipitation is expected to continue to increase in New York State (NYS). Heavy precipitation may negatively affect asthma prevalence through its effect on seasonally varying allergens. We employed a threshold analysis using a time-stratified semi-symmetric bi-directional case-crossover study design to assess the effect of increase in precipitation on asthma (ICD-9 code 493.xx, N=970,903) emergency department (ED) visits between 2005 and 2014 during non-winter months in NYS. Spatially contiguous gridded meteorological data from North American Land Data Assimilation System (NLDAS) were utilized. We used conditional logistic regression models and stratified the analyses by seasons. During non-winter months, we found a small, statistically significant risk of asthma ED visits for precipitation levels above 50mm, with differences by season. These results suggest that heavy precipitation may be related to an increased risk of asthma ED visits. Gridded meteorological estimates provide a means of addressing the gaps in exposure classification, and these findings provide opportunities for further research on interactions with aeroallergens and meteorological conditions in the context of climate and health.

The role of insurance status in the association between short-term temperature exposure and myocardial infarction hospitalizations in New York State.

To evaluate effect modification of the relationship between short-term ambient temperature and MI, by individual-level insurance status (insured vs. uninsured). We identified MI hospitalizations and insurance status across New York State (NYS) hospitals from 1995 to 2015 in the New York Department of Health Statewide Planning and Research Cooperative System database, using International Classification of Diseases codes. We linked short-term ambient temperature (averaging the 6 hours preceding the event [MI hospitalization]) or nonevent control period in patient residential zip codes. We employed a time-stratified case-crossover study design for both insured and uninsured strata, and then compared the group-specific rate ratios. Over the study period, there were 1,095,051 primary MI admissions, 966,475 (88%) among insured patients. During extremely cold temperatures (<5.8 °C) insured patients experienced reduced rates of MI; this was not observed among the uninsured counterparts. At warmer temperatures starting at the 65th percentile (15.7 °C), uninsured patients had higher rates than insured patients (e.g., for a 6-hour pre-event average temperature increase from the median to the 75th percentile, the rate of MI increased was 2.0% [0.0%-4.0%] higher in uninsured group). Uninsured individuals may face disproportionate rates of MI hospitalization during extreme temperatures.

Mortality burden based on the associations of ambient PM2.5 with cause-specific mortality in China: Evidence from a death-spectrum wide association study (DWAS)

Although studies have estimated the associations of PM2.5 with total mortality or cardiopulmonary mortality, few have comprehensively examined cause-specific mortality risk and burden caused by ambient PM2.5. Thus, this study investigated the association of short-term exposure to PM2.5 with cause-specific mortality using a death-spectrum wide association study (DWAS). Individual information of 5,450,764 deaths during 2013–2018 were collected from six provinces in China. Daily PM2.5 concentration in the case and control days were estimated by a random forest model. A time-stratified case-crossover study design was applied to estimate the associations (access risk, ER) of PM2.5 with cause-specific mortality, which was then used to calculate the population-attributable fraction (PAF) of mortality and the corresponding mortality burden caused by PM2.5. Each 10 μg/m3 increase in PM2.5 concentration (lag03) was associated with a 0.80 % [95 % confidence interval (CI): 0.73 %, 0.86 %] rise in total mortality. We found greater mortality effect at PM2.5 concentrations < 50 μg/m3. Stratified analyses showed greater ERs in females (1.01 %, 95 %CI: 0.91 %, 1.11 %), children ≤ 5 years (2.17 %, 95 %CI: 0.85 %, 3.51 %), and old people ≥ 70 years. We identified 33 specific causes (level 2) of death which had significant associations with PM2.5, including 16 circulatory diseases, 9 respiratory diseases, and 8 other causes. The PAF estimated based on the overall association between PM2.5 and total mortality was 3.16 % (95 %CI: 2.89 %, 3.40 %). However, the PAF was reduced to 2.88 % (95 %CI: 1.88 %, 3.81 %) using the associations of PM2.5 with 33 level 2 causes of death, based on which 250.15 (95 %CI: 163.29, 330.93) thousand deaths were attributable to short-term PM2.5 exposure across China in 2019. Overall, this study provided a comprehensive picture on the death-spectrum wide association between PM2.5 and morality in China. We observed robust positive cause-specific associations of PM2.5 with mortality risk, which may provide more precise basis in assessing the mortality burden of air pollution.

Inclement Weather and Risk of Missing Scheduled Hemodialysis Appointments among Patients with Kidney Failure.

Nonadherence to hemodialysis appointments could potentially result in health complications that can influence morbidity and mortality. We examined the association between different types of inclement weather and hemodialysis appointment adherence. We analyzed health records of 60,135 patients with kidney failure who received in-center hemodialysis treatment at Fresenius Kidney Care clinics across the Northeastern US counties during 2001-2019. County-level daily meteorological data on rainfall, hurricane and tropical storm events, snowfall, snow depth, and wind speed were extracted using National Oceanic and Atmosphere Agency data sources. A time-stratified case-crossover study design with conditional Poisson regression was used to estimate the effect of inclement weather exposures within the Northeastern US region. We applied a distributed lag nonlinear model framework to evaluate the delayed effect of inclement weather for up to 1 week. We observed positive associations between inclement weather and missed appointment (rainfall, hurricane and tropical storm, snowfall, snow depth, and wind advisory) when compared with noninclement weather days. The risk of missed appointments was most pronounced during the day of inclement weather (lag 0) for rainfall (incidence rate ratio [RR], 1.03 per 10-mm rainfall; 95% confidence interval [CI], 1.02 to 1.03) and snowfall (RR, 1.02; 95% CI, 1.01 to 1.02). Over 7 days (lag 0-6), hurricane and tropical storm exposures were associated with a 55% higher risk of missed appointments (RR, 1.55; 95% CI, 1.22 to 1.98). Similarly, 7-day cumulative exposure to sustained wind advisories was associated with 29% higher risk (RR, 1.29; 95% CI, 1.25 to 1.31), while wind gusts advisories showed a 34% higher risk (RR, 1.34; 95% CI, 1.29 to 1.39) of missed appointment. Inclement weather was associated with higher risk of missed hemodialysis appointments within the Northeastern United States. Furthermore, the association between inclement weather and missed hemodialysis appointments persisted for several days, depending on the inclement weather type.

Ambient temperature and air pollution associations with suicide and homicide mortality in California: A statewide case-crossover study

BackgroundHigher ambient temperature and air pollution may contribute to increased risk of behaviors harmful to oneself or to others; however, quantitative evidence is limited. We examined the relationship of deaths due to suicide and homicide with temperature and air pollution in California—a state prone to high levels of both exposures. MethodCalifornia death certificates from 2014 to 2019 were used to identify deaths due to suicide and homicide. Residential data for decedents were used to assign exposure to daily temperature (maximum[Tmax], minimum[Tmin]) and daily average air pollution concentrations (particulate matter <10 μm[PM10] and < 2.5 μm[PM2.5], nitrogen dioxide[NO2], ozone[O3]). Tmin served as a surrogate for nighttime temperature. A time-stratified case-crossover study design using conditional logistic regression was used to assess the effects of daily exposure to temperature and air pollutants on suicide and homicide mortality, adjusting for relative humidity. Effect modification by sex and age was assessed. ResultsWe observed 24,387 deaths due to suicide and 10,767 deaths due to homicide. We found a monotonic temperature association for both outcomes. A 5 °C increase in Tmax at lag-2 and Tmin at lag-0 was associated with 3.1 % (95 % confidence interval [CI]: 1.1 %–5.2 %) and 3.8 % (95%CI: 0.9 %–6.8 %) increased odds of death due to suicide, respectively. The increased odds of homicide mortality per 5 °C increase in Tmax at lag-0 and Tmin at lag-1 were 4.9 % (95%CI: 1.6 %–8.1 %) and 6.2 % (95%CI: 1.6 %–11.0 %), respectively. No air pollutant associations were statistically significant. Temperature associations were robust after adjustment for PM2.5. Some temperature effects were larger among women for suicide and men for homicide mortality, and among those over age 65 years for both outcomes. ConclusionRisk of suicide and homicide mortality increases with increasing daily ambient temperatures. Findings have public health relevance given anticipated increases in temperatures due to global climate change.

Association between air temperature and emergency admission for esophagogastric variceal bleeding: a case-crossover study in Beijing, China

Background and aimsStudies concerning the impact of air temperature on esophagogastric variceal bleeding (EGVB) have yielded conflicting results. Our study aimed to evaluate the correlation between air temperature and EGVB.MethodsA time-stratified case-crossover study design was performed. Patients received emergency gastroscopic hemostasis for upper gastrointestinal bleeding between Jan 1, 2014, and Dec 31, 2018 in the Fifth Medical Center of PLA General Hospital were enrolled. Conditional logistic regression analysis was applied to determine the association between air temperature and EGVB for different lag structures.ResultsA total of 4204 cirrhotic patients diagnosed with EGVB and received emergency gastroscopic hemostasis were enrolled. The mean number of daily EGVB cases peaked in October (2.65 ± 1.69) and fell to the lowest level in July (1.86 ± 1.38), and was 2.38 ± 1.58 in spring, 2.00 ± 1.46 in summer, 2.37 ± 1.58 in autumn, and 2.45 ± 1.58 in winter, respectively (P < 0.0001). In conditional logistic regression analysis, no significant correlations between air temperature and EGVB were observed and no significant difference were found when stratified by age, sex, etiology, liver cancer status, and grade of varices.ConclusionEmergency admission for EGVB showed significant monthly and seasonal fluctuations, while in conditional logistic regression analysis, no association between minimum temperature and emergency admission for EGVB were observed.

Short-term association between ambient air pollution and cardio-respiratory mortality in Rio de Janeiro, Brazil.

Several epidemiological studies have reported associations between ambient air pollution and mortality. However, relatively few studies have investigated this relationship in Brazil using individual-level data. To estimate the short-term association between exposure to particulate matter <10 μm (PM10) and ozone (O3), and cardiovascular and respiratory mortality in Rio de Janeiro, Brazil, between 2012 and 2017. We used a time-stratified case-crossover study design with individual-level mortality data. Our sample included 76,798 deaths from cardiovascular diseases and 36,071 deaths from respiratory diseases. Individual exposure to air pollutants was estimated by the inverse distance weighting method. We used data from seven monitoring stations for PM10 (24-hour mean), eight stations for O3 (8-hour max), 13 stations for air temperature (24-hour mean), and 12 humidity stations (24-hour mean). We estimated the mortality effects of PM10 and O3 over a 3-day lag using conditional logistic regression models combined with distributed lag non-linear models. The models were adjusted for daily mean temperature and daily mean absolute humidity. Effect estimates were presented as odds ratios (OR) with their 95% confidence interval (CI) associated with a 10 μg/m3 increase in each pollutant exposure. No consistent associations were observed for both pollutant and mortality outcome. The cumulative OR of PM10 exposure was 1.01 (95% CI 0.99-1.02) for respiratory mortality and 1.00 (95% CI 0.99-1.01) for cardiovascular mortality. For O3 exposure, we also found no evidence of increased mortality for cardiovascular (OR 1.01, 95% CI 1.00-1.01) or respiratory diseases (OR 0.99, 95% CI 0.98-1.00). Our findings were similar across age and gender subgroups, and different model specifications. We found no consistent associations between the PM10 and O3 concentrations observed in our study and cardio-respiratory mortality. Future studies need to explore more refined exposure assessment methods to improve health risk estimates and the planning and evaluation of public health and environmental policies.

Daily changes in ambient air pollution concentrations and temperature and suicide mortality in Canada: Findings from a national time-stratified case-crossover study

IntroductionWorldwide, approximately 1900 people die by suicide daily. Daily elevations in air pollution and temperature have previously been linked to a higher risk of death from suicide. To date, there have been relatively few studies of air pollution and suicide, particularly at a national level. National analyses play an important role in shaping health policy to mitigate against adverse health outcomes. MethodsWe used a time-stratified case-crossover study design to investigate the influence of short-term (i.e., day to day) interquartile range (IQR) increases in air pollutants (nitrogen dioxide [NO2], ozone [O3], and fine particulate matter [PM2.5]) and temperature on suicide mortality in Canada between 2002 and 2015. For air pollution models, odds ratios (ORs) derived from conditional logistic regression models were adjusted for average daily temperature, and holidays. For temperature models, ORs were adjusted for holidays. Stratified analyses were undertaken by suicide type (non-violent and violent), sex, age, and season. ResultsAnalyses are based on 50,800 suicide deaths. Overall, temperature effects were stronger than those for air pollution. A same day IQR increase in temperature (9.6 °C) was associated with a 10.1% increase (95% confidence interval (CI): 9.0%–11.2%) of death from suicide. For 3-day average increase of O3 (IQR = 14.1 ppb), PM2.5 (IQR = 5.6 μg/m3) and NO2 (IQR = 9.7 ppb) the corresponding risks were 4.7% (95% CI: 3.9, 5.6), 3.4% (95% CI: 3.0, 3.8), and 2.0% (95% CI: 1.1, 2.8), respectively. All pollutants showed stronger associations with suicide during the warmer season (April–September). Stratified analyses revealed stronger associations for both temperature and air pollution in women. ConclusionsDaily increases in air pollution and temperature were found to increase the risk of death from suicide. Females, particularly during warmer season, were most vulnerable to these exposures. Policy decisions related to air pollution and climate change should consider effects on mental health.

Attributable risk and economic burden of pneumonia among older adults admitted to hospital due to short-term exposure to airborne particulate matter: a time-stratified case-crossover study from China.

Many studies have proven the relationship between air pollutants and respiratory diseases, but few studies have assessed the impacts of air particulate matter exposure on older patients with pneumonia. This study aimed to reveal the impacts of short-term exposure to air particulate matter on the daily number of older adult patients hospitalized due to pneumonia and calculate the economic costs attributable to this exposure. We collected inpatient data from 9 city hospitals in Sichuan Province, China, from January 1, 2018, to December 31, 2019, and calculated odds ratios and 95% confidence intervals using a time-stratified case-crossover study design and an attributable risk model to calculate the economic burden due to particulate matter pollution. It was found that for every 10μg/m3 increase in PM2.5 and PM10 concentrations, the daily number of older adult pneumonia inpatients increased by 1.5% (95% CI: 1.010-1.021) and 1.0% (95% CI: 1.006-1.014), respectively. Those 65 ~ 79years old were more susceptible to air particulate pollutants (P < 0.05). During the study period, the total hospitalization costs and out-of-pocket expenses attributable to PM2.5 and PM10 exposure were 44.60 million CNY (6.22%) and 16.03 million CNY (6.21%), respectively, with PM2.5 being the primary influencing factor. This study revealed the relationship between particulate matter pollution and pneumonia among older adults. The role of policies to limit particulate matter concentrations in reducing disease burden among older adults can be further explored.

Ambient temperature and nervous system diseases-related mortality in Japan from 2010 to 2019: A time-stratified case-crossover analysis

BackgroundDespite the substantial disease burden caused by nervous system diseases, few studies have examined the association between ambient temperature and nervous system diseases, especially during cold seasons. Evidence for specific disease subgroups such as Alzheimer's and Parkinson's is also lacking. ObjectivesThis study examined the association between short-term changes in ambient temperature and nervous system diseases-related mortality in ten Japanese prefectures from 1 January 2010 to 31 December 2019. MethodsA two-stage analysis based on a time-stratified case-crossover study design was conducted. A conditional quasi-Poisson regression model with a distributed lag non-linear model for temperature was applied followed by a multivariate random-effects meta-analysis to obtain average associations. Mortality due to all and cause-specific nervous system diseases (major neurodegenerative diseases, Alzheimer's, and Parkinson's) were analyzed, with consideration for sex and age (0–84 and 85+ years old) subgroups. ResultsWe analyzed 162,315 death cases due to nervous system diseases. Cold was associated with all categories of nervous system diseases-related mortality, but not heat. The estimated relative risks for cold, obtained by comparing the 2.5th percentile of daily mean temperature distribution to the minimum mortality temperature (MMT), were 1.43 (95 % CI: 1.28–1.60), 1.37 (95 % CI: 1.17–1.59), 1.53 (95 % CI: 1.07–2.01), and 1.54 (95 % CI: 1.13–2.10) for all nervous system diseases, major neurodegenerative diseases, Alzheimer's, and Parkinson's, respectively. These associations were also observed in the sex and age subgroups in general but without evidence of effect modification. Heat (the 97.5th percentile of daily mean temperature distribution vs. MMT) was associated with Parkinson’s disease-related mortality among those aged 85 years and over. DiscussionCold was associated with an increased risk of nervous system disease-related mortality. The effect of heat was not observed, except for mortality among the elderly aged 85 years and older with Parkinson's disease.

Association between ambient cold exposure and mortality risk in Shandong Province, China: Modification effect of particulate matter size.

Numerous studies have reported the modification of particulate matters (PMs) on the association between cold temperature and health. However, it remains uncertain whether the modification effect may vary by size of PMs, especially in Shandong Province, China where the disease burdens associated with cold temperature and PMs are both substantial. This study aimed to examine various interactive effects of cold exposure and ambient PMs with diameters ≤1/2.5 μm (PM1 and PM2.5) on premature deaths in Shandong Province, China. In the 2013-2018 cold seasons, data on daily mortality, PM1 and PM2.5, and weather conditions were collected from the 1822 sub-districts of Shandong Province. A time-stratified case-crossover study design was performed to quantify the cumulative association between ambient cold and mortality over lag 0-12 days, with a linear interactive term between temperature and PM1 and PM2.5 additionally added into the model. The mortality risk increased with temperature decline, with the cumulative OR of extreme cold (-16.9°C, the 1st percentile of temperature range) being 1.83 (95% CI: 1.66, 2.02), compared with the minimum mortality temperature. The cold-related mortality risk was 2.20 (95%CI: 1.83, 2.64) and 2.24 (95%CI: 1.78, 2.81) on high PM1 and PM2.5 days, which dropped to 1.60 (95%CI: 1.39, 1.84) and 1.60 (95%CI: 1.37, 1.88) on low PM1 and PM2.5 days. PM1 showed greater modification effect for per unit concentration increase than PM2.5. For example, for each 10?g/m3 increase in PM1 and PM2.5, the mortality risk associated with extreme cold temperature increased by 7.6% (95% CI: 1.3%, 14.2%) and 2.6% (95% CI: -0.7%, 5.9%), respectively. The increment of smaller PMs' modification effect varied by population subgroups, which was particularly strong in the elderly aged over 75 years and individuals with middle school education and below. Specific health promotion strategies should be developed towards the greater modification effect of smaller PMs on cold effect.

Criteria air pollutants and hospitalizations of a wide spectrum of cardiovascular diseases: A nationwide case-crossover study in China

Few national studies have systemically examined the effects of criteria air pollutants on cardiovascular morbidity. This study aimed to investigate the associations between all criteria air pollutants and hospitalization of cause-specific cardiovascular diseases (CVD) in China.We obtained data on CVD hospitalization events of four major categories and 12 specific diseases from 153 hospitals distributed in 20 provincial-level regions from 2013 to 2020. We adopted a time-stratified case-crossover study design using individual cases to capture the effect of short-term exposure to six criteria air pollutants on CVD hospitalizations, using conditional logistic regression models. More than 1.1 million CVD hospitalization events were included. The lag pattern exploration demonstrated the largest effect for six air pollutants on lag 0-1 day. PM 2.5 , PM 10 , NO 2 and CO were significantly associated with increased hospitalization from ischemic heart diseases, cerebrovascular diseases, other heart diseases, and five specific causes of CVD. The effect estimates of NO 2 were the most robust when adjusting for co-pollutants. The concentration-response curves were positive and linear for most pollutant-endpoint pairs (except for O 3 ), and these positive associations remained even below the 24-hour levels recommended by WHO Air Quality Guidelines and China Air Quality Standards.This nationwide case-crossover study in China demonstrated that short-term exposure to multiple ambient air pollutants may significantly increase the risk of cause-specific CVD hospitalizations even under the most stringent air quality regulations, striking an alert for potential CVD patients against these environmental risk factors. • A national hospital-based registry for a wide spectrum of CVD hospitalization. • We evaluated the associations of short-term exposure to six criteria air pollutants. • PM 2.5 , PM 10 , NO 2 and CO were significantly associated with increased CVD hospitalization. • Five specific causes of CVDs were closely linked with exposure to air pollution. • We observed adverse effects of air pollution below the recent WHO Air Quality Guidelines.