Within-City Variation in Reactive Oxygen Species from Fine Particle Air Pollution and COVID-19.

Rationale: Evidence linking outdoor air pollution with coronavirus disease (COVID-19) incidence and mortality is largely based on ecological comparisons between regions that may differ in factors such as access to testing and control measures that may not be independent of air pollution concentrations. Moreover, studies have yet to focus on key mechanisms of air pollution toxicity such as oxidative stress. Objectives: To conduct a within-city analysis of spatial variations in COVID-19 incidence and the estimated generation of reactive oxygen species (ROS) in lung lining fluid attributable to fine particulate matter (particulate matter with an aerodynamic diameter ⩽2.5 µm [PM2.5]). Methods: Sporadic and outbreak-related COVID-19 case counts, testing data, population data, and sociodemographic data for 140 neighborhoods were obtained from the City of Toronto. ROS estimates were based on a mathematical model of ROS generation in lung lining fluid in response to iron and copper in PM2.5. Spatial variations in long-term average ROS were predicted using a land-use regression model derived from measurements of iron and copper in PM2.5. Data were analyzed using negative binomial regression models adjusting for covariates identified using a directed acyclic graph and accounting for spatial autocorrelation. Measurements and Main Results: A significant positive association was observed between neighborhood-level ROS and COVID-19 incidence (incidence rate ratio = 1.07; 95% confidence interval, 1.01-1.15 per interquartile range ROS). Effect modification by neighborhood-level measures of racialized group membership and socioeconomic status was also identified. Conclusions: Examination of neighborhood characteristics associated with COVID-19 incidence can identify inequalities and generate hypotheses for future studies.

An ecological analysis of long-term exposure to PM2.5 and incidence of COVID-19 in Canadian health regions.

BACKGROUND: Ambient fine particulate matter (PM2.5) is associated with a wide range of acute and chronic health effects, including increased risk of respiratory infection. However, evidence specifically related to novel coronavirus disease (COVID-19) is limited. METHODS: COVID-19 case counts for 111 Canadian health regions were obtained from the COVID-19 Canada Open Data portal. Annual PM2.5 data for 2000-2016 were estimated from a national exposure surface based on remote sensing, chemical transport modelling and ground observations, and minimum and maximum temperature data for 2000-2015 were based on a national interpolated surface derived from thin-plate smoothing splines. Population counts and sociodemographic data by health region were obtained from the 2016 census, and health data (self-rated health and prevalence of smoking, obesity, and selected chronic diseases) by health region, were obtained from the Canadian Community Health Survey. Data on total number of COVID-19 tests and changes in mobility comparing post-vs. pre-introduction of social distancing measures were available by province. Data were analyzed using negative binomial regression models. RESULTS: After controlling for province, temperature, demographic and health characteristics and days since peak incidence by health region, long-term PM2.5 exposure exhibited a positive association with COVID-19 incidence (incidence rate ratio 1.07, 95% confidence interval 0.97-1.18 per µg/m3). This association was larger in magnitude and statistically significant in analyses excluding provinces that reported cases only for aggregated health regions, excluding health regions with less than median population density, and restricted to the most highly affected provinces (Quebec and Ontario). CONCLUSIONS: We observed a positive association between COVID-19 incidence and long-term PM2.5 exposure in Canadian health regions. The association was larger in magnitude and statistically significant in more highly affected health regions and those with potentially less exposure measurement error. While our results generate hypotheses for further testing, they should be interpreted with caution and require further examination using study designs less prone to bias.

Incident diuretic drug use and adverse respiratory events among older adults with chronic obstructive pulmonary disease.

AIMS: Diuretic drugs may theoretically improve respiratory health outcomes in chronic obstructive pulmonary disease (COPD) through several possible mechanisms, but they might also lead to respiratory harm. We evaluated the association of incident oral diuretic drug use with respiratory-related morbidity and mortality among older adults with COPD. METHODS: This was a population-based, retrospective cohort study using health administrative data from Ontario, Canada, for the period 2008-2013. We identified adults aged 66 years and older with nonpalliative COPD using a validated algorithm. Respiratory-related morbidity and mortality were evaluated within 30 days of incident oral diuretic drug use compared to nonuse using Cox proportional hazard regression and applying inverse probability of treatment weighting using the propensity score to minimize confounding. RESULTS: Out of 99 766 individuals aged 66 years and older with COPD identified, incident diuretic receipt occurred in 51.7%. Relative to controls, incident diuretic users had significantly increased rates for hospitalization for COPD or pneumonia [hazard ratio (HR) 1.22, 95% confidence interval (CI) 1.07-1.40], as well as more emergency room visits for COPD or pneumonia (HR 1.35, 95% CI 1.18-1.56), COPD or pneumonia-related mortality (HR 1.41; 95% CI 1.04-1.92) and all-cause mortality (HR 1.20, 95% CI 1.06-1.35). The increased respiratory-related morbidity and mortality observed were specifically as a result of loop diuretic use. CONCLUSIONS: Incident diuretic drugs, and more specifically loop diuretics, were associated with increased rates of respiratory-related morbidity and mortality among older adults with nonpalliative COPD. Further studies are needed to determine if this association is causative or due to unresolved confounding.

The impact of a history of asthma on long-term outcomes of people with newly diagnosed chronic obstructive pulmonary disease: A population study.

BACKGROUND: Little is known about the natural history of chronic obstructive pulmonary disease (COPD) that has developed from airway remodeling due to asthma, as compared with other COPD phenotypes. OBJECTIVE: We compared long-term health outcomes of individuals with COPD with and without a history of asthma in a population-based cohort study. METHODS: All individuals with physician-diagnosed COPD between the ages 40 and 55 years from 2009 and 2011 were identified and followed until March 2013 through provincial health administrative data (Ontario, Canada). The exposure was a history of asthma at least 2 years before the diagnosis of COPD to ensure it preceded COPD. The hazards of COPD-, respiratory-, and cardiovascular (CV)-related hospitalizations and all-cause mortality were compared between groups using a Cox regression model controlling for demographic characteristics, comorbidities, and level of health care. RESULTS: Among 9053 patients with COPD, 2717 (30%) had a history of asthma. Over a median of 2.9 years, 712 (8%) individuals had a first COPD hospitalization, 964 (11%) a first respiratory-related and 342 (4%) a first CV-related hospitalization, and 556 (6%) died. Controlling for confounding, a history of asthma was significantly associated with COPD and respiratory-related hospitalizations (hazard ratio, 1.53 [95% CI, 1.29-1.82] and hazard ratio, 1.63 [95% CI, 1.14-1.88], respectively), but not with CV-related hospitalizations or all-cause mortality. Additional analyses confirmed that these findings were not likely a result of unmeasured confounding or misclassification. CONCLUSIONS: Middle-aged individuals with physician-diagnosed COPD and a history of asthma had a higher hazard of hospitalizations due to COPD and other respiratory diseases than did those without.

Concurrent physician-diagnosed asthma and chronic obstructive pulmonary disease: A population study of prevalence, incidence and mortality.

OBJECTIVE: We conducted a population-based cohort study to estimate trends in prevalence, incidence, and mortality of concurrent physician-diagnosed asthma and chronic obstructive pulmonary disease (COPD). STUDY DESIGN AND SETTING: Two validated health administrative case definitions were used to identify asthma and COPD among all individuals aged 35 years and older living in Ontario, Canada. Annual asthma, COPD, and concurrent asthma and COPD prevalence, incidence, and mortality, standardized for age and sex, were estimated, and compared from 2002 to 2012, using generalized linear models. RESULTS: Standardized prevalence of concurrent asthma and COPD increased by 10.5%, from 2.9% in 2002 to 3.2% in 2012 overall, but more prominently in women compared to men. Overall, standardized incidence decreased by16%, from 2.5 to 2.1 per 1000 individuals, but increased significantly in young adults. All-cause mortality among patients with concurrent asthma and COPD decreased by 11.2%, from 2.6% to 2.2%. Being diagnosed with both diseases was significantly associated with higher all-cause mortality compared to asthma (OR = 1.56, 95% CI: 1.50-1.58), but not compared to COPD (OR = 0.97, 0.96-0.98), except in young adults aged 35 to 49 years where people with asthma and COPD had higher mortality (OR = 1.21, 1.15-1.27). CONCLUSIONS: In a large North American population, the burden of concurrent physician-diagnosed asthma and COPD is increasing, particularly in women and young adults.

Urban/rural variation in children's bicycle-related injuries.

The objective of this study was to examine bicycle-related injury rates for children living in urban and rural areas. Data on all Canadian children hospitalised because of bicycling-related injuries (1994-1998) were obtained from the Canadian Institute for Health Information (CIHI). Injured children were classified as residing in urban, mixed urban, mixed rural or rural areas. Incidence rates for bicycle-related head injuries and other bicycle-related injuries were calculated. Logistic regression was used to estimate the odds of head injury, controlling for age, sex, socio-economic status (SES), collision with a motor vehicle, and the presence of provincial helmet legislation. In total, 9367 children were hospitalised for a bicycling-related injury over the 4-year-study period. Of these, 21% occurred in rural areas, 18% in mixed rural, 17% in mixed urban, while the remaining 44% occurred in urban areas. The average annual incidence rate for bicycle-related head injuries in children was 18.49 per 100000 for children living in rural areas compared with 10.93 per 100000 for those living in urban areas, 15.49 for children in mixed urban areas and 17.38 for children living in mixed rural areas. This variation may be explained by differences in bicycling exposure, helmet use, hospital admission criteria, or road environments across geographic areas.

Impact of mandatory helmet legislation on bicycle-related head injuries in children: a population-based study.

OBJECTIVE: Childhood bicycle-related head injuries can be prevented through the use of helmets. Although helmet legislation has proved to be a successful strategy for the adoption of helmets, its effect on the rates of head injury is uncertain. In Canada, 4 provinces have such legislation. The objective of this study was to measure the impact of helmet legislation on bicycle-related head injuries in Canadian children. METHODS: Routinely collected data from the Canadian Institute for Health Information identified all Canadian children (5-19 years) who were hospitalized for bicycling-related injuries from 1994-1998. Children were categorized as head or other injury on the basis of International Classification of Diseases, Ninth Revision, codes. Rates of head injuries and other injuries were compared over time in provinces that adopted legislation and those that did not. RESULTS: Of the 9650 children who were hospitalized because of a bicycle-related injury, 3426 sustained injuries to the head and face and the remaining 6224 had other injuries. The bicycle-related head injury rate declined significantly (45% reduction) in provinces where legislation had been adopted compared with provinces and territories that did not adopt legislation (27% reduction). CONCLUSION: This country-wide study compared rates of head injury in regions with and without mandatory helmet legislation. Comparing head injuries with other non-head-injured children controlled for potential differences in children's cycling habits. The strong protective association between helmet legislation and head injuries supports the adoption of helmet legislation as an effective tool in the prevention of childhood bicycle-related head injuries.