Mode of delivery and birth outcomes before and during COVID-19 -A population-based study in Ontario, Canada.

There is lack of clarity on whether pregnancies during COVID-19 resulted in poorer mode of delivery and birth outcomes in Ontario, Canada. We aimed to compare mode of delivery (C-section), birth (low birthweight, preterm birth, NICU admission), and health services use (HSU, hospitalizations, ED visits, physician visits) outcomes in pregnant Ontario women before and during COVID-19 (pandemic periods). We further stratified for pre-existing chronic diseases (asthma, eczema, allergic rhinitis, diabetes, hypertension). Deliveries before (Jun 2018-Feb 2020) and during (Jul 2020-Mar 2022) pandemic were from health administrative data. We used multivariable logistic regression analyses to estimate adjusted odds ratios (aOR) of delivery and birth outcomes, and negative binomial regression for adjusted rate ratios (aRR) of HSU. We compared outcomes between pre-pandemic and pandemic periods. Possible interactions between study periods and covariates were also examined. 323,359 deliveries were included (50% during pandemic). One in 5 (18.3%) women who delivered during the pandemic had not received any COVID-19 vaccine, while one in 20 women (5.2%) lab-tested positive for COVID-19. The odds of C-section delivery during the pandemic was 9% higher (aOR = 1.09, 95% CI: 1.08-1.11) than pre-pandemic. The odds of preterm birth and NICU admission were 15% (aOR = 0.85, 95% CI: 0.82-0.87) and 10% lower (aOR = 0.90, 95% CI: 0.88-0.92), respectively, during COVID-19. There was a 17% reduction in ED visits but a 16% increase in physician visits during the pandemic (aRR = 0.83, 95% CI: 0.81-0.84 and aRR = 1.16, 95% CI: 1.16-1.17, respectively). These aORs and aRRs were significantly higher in women with pre-existing chronic conditions. During the pandemic, healthcare utilization, especially ED visits (aRR = 0.83), in pregnant women was lower compared to before. Ensuring ongoing prenatal care during the pandemic may reduce risks of adverse mode of delivery and the need for acute care during pregnancy.

Association of ever use of e-cigarettes with health and lifestyle variables among young adults: a Canadian health measure survey study.

Research suggests that vaping raises oxidative stress levels and has been implicated in poor mental health. The objective of this study is to assess cross-sectional associations between quality of life (QOL) indicators and e-cigarette (EC) use in young Canadian adults. We used data from the 2016-2017 Canadian Health Measures Survey. We compared physical activity (daily steps), physiological measurements (high-density lipoprotein for cholesterol level), self-perceived life stress, mental health, and QOL between ever-use EC users and non-users. Multivariable binary or ordinal logistic regressions were used to calculate odds ratios (OR) with 95% confidence intervals (CI). Analyses included 905 participants (15-30 years) with 115 (12.7%) reporting EC use and 790 non-users. After adjusting for confounders, compared to non-users, EC users had significantly higher odds of being physically active (OR = 2.19, 95%CI: 1.14-4.20) but also with self-reported extreme life stress (OR = 2.68, 95%CI: 1.45-4.92). Albeit statistically non-significant, EC users also had higher odds of poorer QOL (OR = 1.12, 95%CI: 0.64-1.95). No statistically significant interactions between EC use, cigarette smoking, cannabis consumption and health outcomes were observed. CONCLUSION: Our study found that EC use was independently and significantly associated with increased odds of life stress and an indication of poorer QOL. Ongoing surveillance on young EC users is important to measure the long-term impact of vaping on their physical, mental health and quality of life to target for interventions. WHAT IS KNOWN: • E-cigarette use has been associated with high-risk behaviours and adverse mental health outcomes, such as depression and anxiety. WHAT IS NEW: • E-cigarette users had significantly higher odds of being physically active and higher amounts of life stress.

Association of factors with childhood asthma and allergic diseases using latent class analysis.

We hypothesize that children characterized by deprived factors have poorer health outcomes. We aim to identify clustering of determinants and estimate risk of early childhood diseases. This 1993-2019 longitudinal cohort study combines three Canadian pediatric cohorts and their families. Mothers and children are clustered using latent class analysis (LCA) by 16 indicators in three domains (maternal and newborn; socioeconomic status [SES] and neighbourhood; environmental exposures). Hazard ratios (HR) of childhood asthma, allergic rhinitis (AR), and eczema are quantified with Cox proportional hazard (PH) regression. Rate ratios (RR) of children's health services use (HSU) are estimated with Poisson regression. Here we report the inclusion of 15,724 mother-child pairs; our LCA identifies four mother-clusters. Classes 1 and 2 mothers are older (30-40 s), non-immigrants with university education, living in high SES neighbourhoods; Class 2 mothers have poorer air quality and less greenspace. Classes 3 and 4 mothers are younger (20-30 s), likely an immigrant/refugee, with high school-to-college education, living in lower SES neighborhoods with poorer air quality and less greenspace. Children's outcomes differ by Class, in comparison to Class 1. Classes 3 and 4 children have higher risks of asthma (HR 1.24, 95% CI 1.11-1.37 and HR 1.39, 95% CI 1.22-1.59, respectively), and similar higher risks of AR and eczema. Children with AR in Class 3 have 20% higher all-cause physician visits (RR = 1.20, 95% CI 1.10-1.30) and those with eczema have 18% higher all-cause emergency department visits (RR = 1.18, 95% CI 1.09-1.28) and 14% higher all-cause physician visits (RR = 1.14, 95% CI 1.09-1.19). Multifactorial-LCA mother-clusters may characterize associations of children's health outcomes and care, adjusting for interrelationships.

Vaping and Health Service Use: A Canadian Health Survey and Health Administrative Data Study.

Rationale: Emerging research suggests that e-cigarette (EC) use may have detrimental health effects, increasing the burden on healthcare systems. Objectives: To determine whether young EC users had increased asthma, asthma attacks, and health services use (HSU). Methods: This cohort study used the linked Canadian Community Health Survey (cycles 2015-16 and 2017-18) and health administrative data (January 2015-March 2018). A propensity score method matched self-reported EC users to up to five control subjects. Matched multivariable logistic and negative binomial regressions were used to calculate odds ratios, rate ratios (RRs), and 95% confidence intervals (CIs) with EC use as the exposure and asthma, asthma attacks, and all-cause HSU as the outcomes. Results: Analyses included 2,700 matched Canadian Community Health Survey participants (15-30 yr), 505 (2.4% of 20,725 participants) EC users matched to 2,195 nonusers. After adjusting for confounders, EC users with asthma had over twofold higher odds of having an asthma attack in the last 12 months (odds ratio, 2.30; 95% CI, 1.29-4.12). Dual EC and conventional tobacco users had a twofold increased all-cause HSU rate compared with nonusers who never smoked tobacco (RR, 2.13; 95% CI, 1.53-2.98). This rate was greater than that for EC users who never smoked tobacco (RR, 1.73; 95% CI, 1.00-3.00) and non-EC users who regularly smoke tobacco (RR, 1.72; 95% CI, 1.29-2.29). Compared with male nonusers, female EC users had the highest increased all-cause HSU (RR, 1.94; 95% CI, 1.39-2.69) over male EC users and female nonusers (RR, 1.13; 95% CI, 0.86-1.48; RR, 1.41; 95% CI, 1.16-1.71, respectively). Conclusions: Current EC use is associated with significantly increased odds of having an asthma attack. Furthermore, concurrent EC use and conventional cigarette smoking are associated with a higher rate of all-cause HSU. The odds of asthma attack and all-cause HSU were highest among women. Thus, EC use may be an epidemiological biomarker for youth and young adults with increased health morbidity.

Healthcare utilization in Canadian children and young adults with asthma during the COVID-19 pandemic.

Literature is limited regarding the COVID-19 pandemic's impact on health services use in younger Canadian populations with asthma. We utilized health administrative databases from January 2019-December 2021 for a population-based cross-sectional study to identify Ontario residents 0-25 years old with physician-diagnosed asthma and calculate rates of healthcare use. Multivariable negative binomial regression analysis was used to adjust for confounders. We included 716,690 children and young adults ≤25 years. There was a sharp increase of ICS and SABA prescription rates at the start of the pandemic (March 2020) of 61.7% and 54.6%, respectively. Monthly virtual physician visit rates increased from zero to 0.23 per 100 asthma population during the pandemic. After adjusting for potential confounders, rate ratios (RR) with 95% confidence intervals (CI) showed that the pandemic was associated with significant decrease in hospital admissions (RR = 0.21, 95% CI: 0.18-0.24), emergency department visits (RR = 0.35, 95% CI: 0.34-0.37), and physician visits (RR = 0.61, 95% CI: 0.60-0.61). ICS and SABA prescriptions filled also significantly decreased during the pandemic (RR = 0.58, 95% CI: 0.57-0.60 and RR = 0.47, 95% CI: 0.46-0.48, respectively). This Canadian population-based asthma study demonstrated a dramatic decline in physician and emergency department visits, hospitalizations, and medication prescriptions filled during the COVID-19 pandemic. An extensive evaluation of the factors contributing to an 80% reduction in the risk of hospitalization may inform post-pandemic asthma management.

Does early life exposure to exogenous sources of reactive oxygen species (ROS) increase the risk of respiratory and allergic diseases in children? A longitudinal cohort study.

BACKGROUND: Excess reactive oxygen species (ROS) can cause oxidative stress damaging cells and tissues, leading to adverse health effects in the respiratory tract. Yet, few human epidemiological studies have quantified the adverse effect of early life exposure to ROS on child health. Thus, this study aimed to examine the association of levels of ROS exposure at birth and the subsequent risk of developing common respiratory and allergic diseases in children. METHODS: 1,284 Toronto Child Health Evaluation Questionnaire (T-CHEQ) participants were followed from birth (born between 1996 and 2000) until outcome, March 31, 2016 or loss-to-follow-up. Using ROS data from air monitoring campaigns and land use data in Toronto, ROS concentrations generated in the human respiratory tract in response to inhaled pollutants were estimated using a kinetic multi-layer model. These ROS values were assigned to participants' postal codes at birth. Cox proportional hazards regression models, adjusted for confounders, were then used to estimate hazard ratios (HR) with 95% confidence intervals (CI) per unit increase in interquartile range (IQR). RESULTS: After adjusting for confounders, iron (Fe) and copper (Cu) were not significantly associated with the risk of asthma, allergic rhinitis, nor eczema. However, ROS, a measure of the combined impacts of Fe and Cu in PM2.5, was associated with an increased risk of asthma (HR = 1.11, 95% CI: 1.02-1.21, p < 0.02) per IQR. There were no statistically significant associations of ROS with allergic rhinitis (HR = 0.96, 95% CI: 0.88-1.04, p = 0.35) and eczema (HR = 1.03, 95% CI: 0.98-1.09, p = 0.24). CONCLUSION: These findings showed that ROS exposure in early life significantly increased the childhood risk of asthma, but not allergic rhinitis and eczema.

Is overreliance on short-acting ß2-agonists associated with health risks in the older asthma population?

Recent Global Initiative for Asthma (GINA) recommendations reduce the role of short-acting ß2-agonist (SABA) premised on the associated exacerbation risk. The widely accepted SABA risk profile is based on limited data described 30 years ago. This GINA paradigm shift demands an examination of SABA risks in a modern therapeutic era. Recent studies confirm that SABA overuse is common and associated with adverse outcomes. This study aimed to determine associations between SABA use, all-cause mortality and asthma exacerbations in an older North American asthma population. In this population-based cohort study, individuals with prevalent asthma (2006-2015) aged ≥65 years, eligible for provincial drug coverage, were included. Annual SABA canisters filled (0, 1-2, 3-5, ≥6) was the primary exposure. Hazard ratios (HRs) with 95% CIs were estimated using Cox proportional hazard regression, adjusted for confounders. There were 59 533 asthma individuals; 14% overused SABA (≥3 canisters annually). Compared to those who used <3 canisters, the adjusted HRs of death for those who used 3-5 and ≥6 canisters were 1.11 (95% CI: 1.02-1.22, p=0.0157) and 1.56 (95% CI: 1.41-1.71, p<0.0001), respectively. Severe asthma exacerbation rates for ≥3 and <3 canisters/year were 7.5% and 2.1%, respectively. The adjusted HRs of severe asthma exacerbations were 1.59 (95% CI: 1.40-1.82, p<0.0001) and 2.26 (95% CI: 1.96-2.60, p<0.0001) in those who used 3-5 and ≥6 SABA canisters per year, respectively. In Canada, 1 in 7 individuals with asthma overused SABA associated with increased risks of severe asthma exacerbations and death. The adverse impacts of SABA overuse continue 30 years after early publications.

Did Emergency Department Visits in Infants and Young Children Increase in the Last Decade?: An Ontario, Canada Study.

OBJECTIVES: The aims of the study were to measure overall trends and to identify leading causes for pediatric emergency department (ED) visits among children aged 0 to 4 years. METHODS: We conducted an 11-year population-based open cohort study using health administrative data from 2008 to 2018 in Ontario, Canada. All ED visits were extracted from the National Ambulatory Care Reporting System, along with the most responsible cause of each visit. Annual ED visit rates were calculated per 100 children in each year. Overall and disease-specific rates for all children were calculated and then stratified by sex and age groups. Relative percentage change in rates between 2008 and 2018 were calculated and compared using standardized differences (SDIFs). Statistical significance of time trends was tested using Poisson regression. RESULTS: This study included an average of 911,566 children from 2008 to 2018. All-cause ED visit rates increased by 28.2% from 2008 to 2018 (43.24-55.42 per 100, SDIF >0.1). Respiratory diseases were consistently the top cause of ED visits, and contributed to 1 in 3 ED visits in 2018. These respiratory conditions include asthma, asthma-related diseases (bronchiolitis, bronchitis, influenza, and pneumonia), and other respiratory diseases. Respiratory ED visit rates increased by 32.8% from 2008 to 2018 (11.51-15.28 per 100, SDIF <0.1), driven by a 46.4% (14.58-21.35 per 100, SDIF >0.1) increase among children younger than 1 year. There was a 78.0% increase in ED visits for bronchiolitis in infants (1.45-2.58 per 100, SDIF <0.1). CONCLUSIONS: Respiratory diseases like bronchiolitis among infants were the consistent leading cause for ED visits. All-cause ED visit rates among young children increased by 28.17% from 2008 to 2018.

Effect of smoke-free legislation on respiratory health services use in children with asthma: a population-based open cohort study in Ontario, Canada.

OBJECTIVE: This study will add to existing literature by examining the impact of smoke-free legislation in outdoor areas among children with asthma. We aimed to examine the effect of the 2015 Smoke-Free Ontario Act (SFOA) amendment, which prohibited smoking on patios, playgrounds and sports fields, on health services use (HSU) rates in children with asthma. METHODS: We conducted a population-based open cohort study using health administrative data from the province of Ontario, Canada. Each year, all Ontario residents aged 0-18 years with physician diagnosed asthma were included in the study. Annual rates of HSU (emergency department (ED) visits, hospitalisations and physician office visits) for asthma and asthma-related conditions (eg, bronchitis, allergic rhinitis, influenza and pneumonia) were calculated. Interrupted time-series analysis, accounting for seasonality, was used to estimate changes in HSU following the 2015 SFOA. RESULTS: The study population ranged from 618 957 individuals in 2010 to 498 812 in 2018. An estimated average increase in ED visits for asthma in infants aged 0-1 years of 0.42 per 100 individuals (95% CI: 0.09 to 0.75) and a 57% relative increase corresponding to the 2015 SFOA was observed. A significant decrease in ED visits for asthma-related conditions of 0.19 per 100 individuals (95% CI: -0.37 to -0.01) and a 22% relative decrease corresponding to the 2015 SFOA was observed. CONCLUSION: Based on the observed positive effect of restricting smoking on patios, playgrounds and sports fields on respiratory morbidity in children with asthma, other jurisdictions globally should consider implementing similar smoke-free policies.

Does exposure to air pollution increase the risk of acute care in young children with asthma? An Ontario, Canada study.

Owing to their greater outdoor activity and ongoing lung development, children are particularly vulnerable to the harmful effects of exposure to fine particulate matter (PM2.5). However, the effects of PM2.5 components are poorly understood. This study aimed to use a longitudinal birth cohort of children with physician-diagnosed incident asthma to investigate the effect of PM2.5 components at birth on morbidity measured by health services utilization. Of 1277 Toronto Child Health Evaluation Questionnaire (T-CHEQ) participants, the study population included 362 children diagnosed with asthma who were followed for a mean of 13 years from birth until March 31, 2016, or loss-to-follow-up. Concentrations of PM2.5 and its components were assigned based on participants' postal codes at birth. Study outcomes included counts of asthma, asthma-related, and all-cause health services use. Poisson regression in single-, two-, and multi-pollutant models was used to estimate rate ratios (RR) per interquartile range (IQR) increase of exposures. Covariates were included in all models to further adjust for potential confounding. The adjusted RR for sulfate (SO4) and all-cause hospitalizations was statistically significant with RR = 2.23 (95% confidence interval [CI]: 1.25-3.96) in a multi-pollutant model with nitrogen dioxide (NO2) and ozone (O3). In multi-pollutant models with oxidants, the adjusted RRs for SO4 of all-cause hospitalizations and emergency department (ED) visits were also statistically significant with RR = 2.31 (95% CI: 1.32-4.03) and RR = 1.39 (95% CI: 1.02-1.90), respectively. While unadjusted single-pollutant RRs for asthma-specific and asthma-related health services use with the SO4 component of PM2.5 were above one, none were statistically significant. This study found significant associations with exposure to SO4 in PM2.5 and all-cause acute care, chiefly for hospitalizations, in children with asthma.

Correlation of ambient temperature and COVID-19 incidence in Canada.

The SARS-CoV-2 is a novel coronavirus identified as the cause of COVID-19 and, as the pandemic evolves, many have made parallels to previous epidemics such as SARS-CoV (the cause of an outbreak of severe acute respiratory syndrome [SARS]) in 2003. Many have speculated that, like SARS, the activity of SARS-CoV-2 will subside when the climate becomes warmer. We sought to determine the relationship between ambient temperature and COVID-19 incidence in Canada. We analyzed over 77,700 COVID-19 cases from four Canadian provinces (Alberta, British Columbia, Ontario, and Quebec) from January to May 2020. After adjusting for precipitation, wind gust speed, and province in multiple linear regression models, we found a positive, but not statistically significant, association between cumulative incidence and ambient temperature (14.2 per 100,000 people; 95%CI: -0.60-29.0). We also did not find a statistically significant association between total cases or effective reproductive number of COVID-19 and ambient temperature. Our findings do not support the hypothesis that higher temperatures will reduce transmission of COVID-19 and warns the public not to lose vigilance and to continue practicing safety measures such as hand washing, social distancing, and use of facial masks despite the warming climates.

UV, ozone, and COVID-19 transmission in Ontario, Canada using generalised linear models.

BACKGROUND: Quantifying the impact of environmental factors on COVID-19 transmission is crucial in preventing more cases. Ultraviolet (UV) radiation and ozone (O3) have reported antimicrobial properties but few studies have examined associations with community infectivity of COVID-19. Research suggests UV light can be preventative while the effect of O3 is contested. We sought to determine the relationship between UV, O3, and COVID-19 incidence in Ontario, Canada. METHODS: In our time series analyses, we calculated daily incidence rates and reproductive number (Rt) from 34,975 cases between January and June 2020 across 34 Ontario Public Health Units. We used generalised linear models, adjusting for potential confounders, to calculate point estimates (PE) and 95% confidence intervals (CI) for UV and O3. Analyses were further stratified by age groups and outbreaks at institutions versus community. RESULTS: We found that 1-week averaged UV was significantly associated with a 13% decrease (95% CI: 0.80-0.96) in overall COVID-19 Rt, per unit increase. A negative association with UV was also significant among community outbreaks (PE: 0.88, 95% CI: 0.81-0.96) but not institutional outbreaks (PE: 0.94, 95% CI: 0.85-1.03). A positive association of O3 with COVID-19 incidence is strongly suggested among institutional outbreak cases (PE: 1.06, 95% CI: 1.00-1.13). CONCLUSION: Our study found evidence to support the hypothesis that higher UV reduced transmission of COVID-19 and some evidence that ground-level O3 positively influenced COVID-19 transmission. Setting of infection should be strongly considered as a factor in future research. UV and O3 may explain some of COVID-19's seasonal behaviour.