Canadian Health Regions Research Articles

System-Based Interventions to Address Physician Burnout: A Qualitative Study of Canadian Family Physicians' Experiences During the COVID-19 Pandemic.

Medical professionals experienced high rates of burnout and moral distress during the COVID-19 pandemic. In Canada, burnout has been linked to a growing number of family physicians (FPs) leaving the workforce, increasing the number of patients without access to a regular doctor. This study explores the different factors that impacted FPs' experience with burnout and moral distress during the pandemic, with the goal of identifying system-based interventions aimed at supporting FP well-being and improving retention. We conducted semi-structured qualitative interviews with FPs across four health regions in Canada. Participants were asked about the roles they assumed during different stages of the pandemic, and they were also encouraged to describe their well-being, including relevant supports and barriers. We used thematic analysis to examine themes relating to FP mental health and well-being. We interviewed 68 FPs across the four health regions. We identified two overarching themes related to moral distress and burnout: (1) inability to provide appropriate care, and (2) system-related stressors and buffers of burnout. FPs expressed concern about the quality of care their patients were able to receive during the pandemic, citing instances where pandemic restrictions limited their ability to access critical preventative and diagnostic services. Participants also described four factors that alleviated or exacerbated feelings of burnout, including: (1) workload, (2) payment model, (3) locum coverage, and (4) team and peer support. The COVID-19 pandemic limited FPs' ability to provide quality care to patients, and contributed to increased moral distress and burnout. These findings highlight the importance of implementing system-wide interventions to improve FP well-being during public health emergencies. These could include the expansion of interprofessional team-based models of care, alternate remuneration models for primary care (ie, non-fee-for-service), organized locum programs, and the availability of short-term insurance programs to cover fixed practice operating costs.

Bayesian inference on sparse multinomial data using smoothed Dirichlet distribution with an application to COVID-19 data

We develop a Bayesian approach for estimating multinomial cell probabilities using a smoothed Dirichlet prior. The most important feature of the smoothed Dirichlet prior is that it forces the probabilities of neighboring cells to be closer to each other than under the standard Dirichlet prior. We propose a shrinkage-type estimator using this Bayesian approach to estimate multinomial cell probabilities. The proposed estimator allows us to borrow information across other multinomial populations and cell categories simultaneously to improve the estimation of cell probabilities, especially in a context of sparsity with ordered categories. We demonstrate the proposed approach using COVID-19 data and estimate the distribution of positive COVID-19 cases across age groups for Canadian health regions. Our approach allows improved estimation in smaller health regions where few cases have been observed.

Understanding the Associations among Social Vulnerabilities, Indigenous Peoples, and COVID-19 Cases within Canadian Health Regions.

Indigenous Peoples are at an increased risk for infectious disease, including COVID-19, due to the historically embedded deleterious social determinants of health. Furthermore, structural limitations in Canadian federal government data contribute to the lack of comparative rates of COVID-19 between Indigenous and non-Indigenous people. To make visible Indigenous Peoples’ experiences in the public health discourse in the midst of COVID-19, this paper aims to answer the following interrelated research questions: (1) What are the associations of key social determinants of health and COVID-19 cases among Canadian health regions? and (2) How do these relationships relate to Indigenous communities? As both proximal and distal social determinants of health conjointly contribute to COVID-19 impacts on Indigenous health, this study used a unique dataset assembled from multiple sources to examine the associations among key social determinants of health characteristics and health with a focus on Indigenous Peoples. We highlight key social vulnerabilities that stem from systemic racism and that place Indigenous populations at increased risk for COVID-19. Many Indigenous health issues are rooted in the historical impacts of colonization, and partially invisible due to systemic federal underfunding in Indigenous communities. The Canadian government must invest in collecting accurate, reliable, and disaggregated data on COVID-19 case counts for Indigenous Peoples, as well as in improving Indigenous community infrastructure and services.

Disparities in modifiable cancer risk factors among Canadian provinces, territories, and health regions

Background Data about small area estimates of cancer risk factors are difficult to obtain in Canada. The current study aims to provide an assessment of the prevalence of different behavioral risk factors of cancer at the level of Canadian provinces/territories and sub provincial health regions/units. Methods Canadian Community Health Survey (CCHS) datasets for 2017/2018 were reviewed and adult participants (≥ 18 years old) were included. Baseline demographic data and health behaviors (including ever-smoking, current smoking, alcohol drinking in the past 12 months, below-recommended physical activity, and obesity) were reviewed. Prevalence of each of these behaviors within different provinces/territories as well as within each health region was reviewed. Multivariable logistic regression analysis was then done to examine the association between place of residence and cancer risk factors. Results A total of 104,636 adult participants were included in the current analysis. For ever-smoking, the highest prevalence was noted in Nunavut (79.7%); for current smoking, the highest prevalence was noted in Nunavut (67.2%); for alcohol drinking in the past 12 months, the highest prevalence was noted in Quebec (89.3%); for below-recommended physical activity, the highest prevalence was noted in Nunavut (51.3%); for obesity, the highest prevalence was noted in Northwest territories (31.5%). Compared to individuals living within a territory, individuals living within a province were less likely to ever smoke (OR: 0.62; 95% CI: 0.54–0.71), currently smoke (OR: 0.51; 95% CI: 0.45–0.59), be obese (OR: 0.82; 95% CI: 0.71–0.95), but more likely to drink alcohol in the past 12 months (OR: 1.41; 95% CI: 1.20–1.65). There is no difference between both categories with regards to physical activity (OR: 1.02; 95% CI: 0.89–1.15). Conclusions There is a general province/territory disparity in the prevalence of different modifiable cancer risk factors as well as disparity between individual provinces/health regions in Canada.

Lessons learned implementing and managing the DIVERT-CARE trial: practice recommendations for a community-based chronic disease self-management model

BackgroundChronic disease management models of care provide an opportunity to assist home care clients to manage their disease burden. However, pragmatic trial management practices and lessons learned from such models are poorly illustrated in the literature.MethodsWe describe the processes of implementing a community-based cardiorespiratory self-management model, known as DIVERT-CARE, across the home care programs of three health regions in Canada. The DIVERT-CARE model is a multi-component complex intervention that identifies home care clients at the highest risk of deterioration and provides them with resources and capacity to manage their conditions. We conducted a retrospective analysis of baseline participant characteristics, needs assessments, reviewed findings from site visits and a national workshop with study partners, and examined other study documentation.ResultsThree home care regions in Canada participated in the study. A robust and data-driven review of each site was necessary to understand the local context, home care caseloads, structure of local systems, and intensity of resources, which influenced study processes. The creation of an intervention framework highlighted the need to adapt the intervention in a way that was sensitive to the local context while maintaining intervention outcomes.ConclusionOur detailed review showcases the relevant activities and on-the-ground steps needed to manage and conduct a multi-site pragmatic trial in home care. This example can help other researchers in implementing multi-disciplinary and multi-component care models for practice-based research.

A Predictive Model for Temporal Artery Biopsy in the Setting of Suspected Giant Cell Arteritis: A Validation Study.

A previously published predictive model based on threshold parameters for erythrocyte sedimentation rate, c-reactive protein, and platelet count demonstrated that 40% of patients who underwent biopsy may not have required it. The current study was performed to evaluate the model's performance on an independent data set. This is a retrospective consecutive series of patients undergoing temporal artery biopsy (TAB) in a single health region in Canada. The model was applied to a multicenter cohort of patients undergoing TAB by a variety of surgical services. A centralized pathological database serving multiple institutions and surgical services was used to identify patients undergoing TAB. Over a 7-year period, patients undergoing TAB were identified via a central pathological database. Those who had concurrent illnesses which would likely affect erythrocyte sedimentation rate, c-reactive protein, and platelet count, patients on steroids for >2 weeks by the time of biopsy, and those with missing serum markers were excluded. The previously developed model was applied to the 222 patients enrolled. The model correctly identified 29% of patients with a pretest probability of 0% for a positive biopsy and 9% with a pretest probability of 100%, suggesting that in total, 38% of patients could have avoided TAB. The results of this independent data set support the previously published predictive formula. Utilizing a simple, clinically applicable predictive model of the pretest probabilities, approximately 38% of TAB currently being performed may be avoided. The results suggest that evaluation with a prospective multicentre study would be appropriate.

Studying the social determinants of COVID-19 in a data vacuum.

Race‐based and other demographic information on COVID‐19 patients is not being collected consistently across provinces in Canada. Therefore, whether the burden of COVID‐19 is falling disproportionately on the shoulders of particular demographic groups is relatively unknown. In this article, we first provide an overview of the available geographic and demographic data related to COVID‐19. We then make creative use of these existing data to fill the vacuum and identify key demographic risk factors for COVID‐19 across Canada's health regions. Drawing on COVID‐19 counts and tabular census data, we examine the association between communities’ demographic composition and the number of COVID‐19 infections. COVID‐19 infections are higher in communities with larger shares of Black and low‐income residents. Our approach offers a way for researchers and policymakers to use existing data to identify communities nationwide that are vulnerable to the pandemic in the absence of more detailed demographic and more granular geographic data.

Priorities for End-of-Life Care Reporting in Nursing Homes: Results From a Mixed-Methods Study

The aim of the “Trajectories” project is to compile measures of nursing home (NH) quality to better characterize the final year of life for residents. In the first phase, we worked with various stakeholder groups to identify their priorities to focus the selection of possible outcomes relevant to end-of-life needs. Policy- and decision-makers from 5 Canadian health regions participated in an on-line, modified Delphi process to reach consensus on 3-4 measures of each burdensome symptoms and potentially inappropriate care practices. NH residents and families or care aides participated in an interview process using the Action Project Method. To date, all participants identified pain, mental health care, polypharmacy, and dyspnea as priorities. Policy- and decision-makers additionally identified infections and acute care transfers as priorities, while residents and families additionally identified mobility, cognition, and pressure ulcer care as priorities. There was general consistency across groups in terms of priorities but additional measures seemed to reflect either a system-wide or more personal perspective, depending on the source. Data collection with frontline staff and managers is on-going. Moving forward, we will use this list of prioritized outcomes to quantitatively assess the trajectories of these outcomes and associated factors, and to create a profile that allows for monitoring of end-of-life care in NHs.

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

BackgroundAmbient 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. MethodsCOVID-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. ResultsAfter 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). ConclusionsWe 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.

Less than five is less than ideal: replacing the "less than 5 cell size" rule with a risk-based data disclosure protocol in a public health setting.

The Winnipeg Regional Health Authority (WRHA) is one of the largest and most diverse health regions in Canada. Within the WRHA, the Population and Public Health (PPH) Surveillance Team provides epidemiological support across a variety of public health service areas. We developed and deployed a risk-based data disclosure protocol that balances the need to share public health surveillance data with the need to protect personal health information. Unlike the conventional data disclosure standard adopted in Manitoba (suppress cell sizes < 5), the new protocol is based upon a risk-based re-identification approach that focuses on the size of the denominator instead of the numerator. This approach has allowed for innovation in data dissemination infrastructure within the unit that would not have been possible previously, including the deployment of public-facing cloud-based interactive maps and dashboards. It has also resulted in strengthened protection of personal health information as the risk of re-identification can now be precisely calculated across all data release situations. In challenging the "cell size less than five" rule, this project is an example of how a scientifically based data disclosure protocol can support a public health organization in meaningful sharing of population health data with community partners and the public. This helps ensure that program and policy responses are empirically based, strategically focused, and cross-jurisdictionally coordinated.

PL04: Comparison of the cost and the quality of the care provided to low acuity patients in an emergency department and a walk-in clinic

Introduction: Low acuity patients have been controversially tagged as a source of emergency department (ED) misuse. Authorities for many Canadian health regions have set up policies so these patients preferably present to walk-in clinics (WIC). We compared the cost and quality of the care given to low acuity patients in an academic ED and a WIC of Québec City during fiscal year 2015-16. Methods: We conducted an ambidirectional (prospective and retrospective) cohort study using a time-driven activity-based costing method. This method uses duration of care processes (e.g., triage) to allocate to patient care all direct costs (e.g., personnel, consumables), overheads (e.g., building maintenance) and physician charges. We included consecutive adult patients, ambulatory at all time and discharged from the ED or WIC with a diagnosis of upper respiratory tract infection (URTI), urinary tract infection (UTI) or low back pain. Mean cost [95%CI] per patient per condition was compared between settings after risk-adjustment for age, sex, vital signs, number of regular medications and co-morbidities using generalized log-gamma regression models. Proportions [95%CI] of antibiotic prescription and chest X-Ray use in URTI, compliance with provincial guidelines on use of antibiotics in UTI, and column X-Ray use in low back pain were compared between settings using a Pearson Chi-Square test. Results: A total of 409 patients were included. ED and WIC groups were similar in terms of age, sex and vital signs on presentation, but ED patients had a greater burden of comorbidities. Adjusted mean cost (2016 CAN$) of care was significantly higher in the ED than in the WIC (p &amp;lt; 0.0001) for URTI (78.42[64.85-94.82] vs. 59.43[50.43-70.06]), UTI (78.88[69.53-89.48] vs. 53.29[43.68-65.03]), and low back pain (87.97[68.30-113.32] vs. 61.71[47.90-79.51]). For URTI, antibiotics were more frequently prescribed in the WIC (44.1%[34.3-54.3] vs. 5.8%[1.2-16.0]; p &amp;lt; 0.0001) and chest X-Rays, more frequently used in the ED (26.9%[15.6-41.0] vs. 13.7%[7.7-22.0]; p = 0.05). No significant differences were observed in the compliance with guidelines on use of antibiotics in UTI and in the use of column X-Ray in low back pain. Conclusion: Total cost of care for low acuity patients is lower in walk-in clinics than in EDs. However, our results suggest that quality-of-care issues should be considered in determining the best alternate setting for treating ambulatory emergency patients.

Nursing Home Length of Stay in 3 Canadian Health Regions: Temporal Trends, Jurisdictional Differences, and Associated Factors

ObjectivesTo assess (1) temporal changes (2008–2015) in nursing home (NH) length of stay (LoS) in 3 Canadian health jurisdictions (Edmonton, Calgary, Winnipeg), (2) resident admission characteristics associated with LoS, and (3) temporal changes of admission characteristics in each of the 3 jurisdictions. DesignRetrospective cohort study using data previously collected in Translating Research in Elder Care (TREC), a longitudinal program of applied health services research in Canadian NHs. Setting and participants7817 residents admitted between January 2008 and December 2015 to a stable cohort of 18 NHs that have consistently participated in TREC since 2007. MethodsLoS was defined as time between a resident's first NH admission and final discharge from the NH sector. Analyses included descriptive statistics, Kaplan Meier estimates (unadjusted LoS), and Cox proportional hazard regressions (adjusted LoS), adjusted for resident characteristics (eg, age, cognitive performance, and health instability). We also controlled for NH size and ownership. ResultsIn jurisdictions with increasing care needs, unadjusted median LoS [95% confidence interval (CI)] decreased over time (2008 and 2009 vs 2014 and 2015 admissions); in Calgary from 1.837 (95% CI 1.618, 2.275) to 1.328 (95% CI 1.185, 1.489) years and in Edmonton from 1.927 (95% CI 1.725, 2.188) to 1.073 (95% CI 0.936, 1.248) years. In Winnipeg, care needs and LoS remained constant (2.163, 95% CI 1.867, 2.494, vs 2.459, 95% CI 2.155, 2.883, years). Resident characteristics including higher physical dependency [hazard ratio (HR) 1.205, 95% CI 1.133, 1.282], higher cognitive impairment (HR 1.112, 95% CI 1.042, 1.187), or higher health instability (HR 1.333, 95% CI 1.224, 1.452) were associated with lower LoS. Adjustment for resident characteristics reduced jurisdictional LoS differences and rendered temporal LoS differences within jurisdictions statistically nonsignificant. Conclusions/ImplicationsIn jurisdictions where care needs at admission have increased since 2008, resident LoS has decreased. Jurisdictional differences in care needs and LoS indicate that health policies may affect these outcomes. Variations of resident outcomes by policy environment require additional scrutiny.

Variability in ambient ozone and fine particle concentrations and population susceptibility among Canadian health regions

ObjectivesTo estimate the proportion of the Canadian population that is more susceptible to adverse effects of ozone (O3) and fine particle (PM2.5) air pollution exposure and how this varies by health region alongside ambient concentrations of O3 and PM2.5.MethodsUsing data from the census, the Canadian Community Health Survey, vital statistics and published literature, we generated cross-sectional estimates for 2014 of the proportions of the Canadian population considered more susceptible due to age, chronic disease, pregnancy, outdoor work, socio-economic status, and diet. We also estimated 2010–2012 average concentrations of O3 and PM2.5. Analyses were conducted nationally and for 110 health regions.ResultsRestrictive criteria (age < 10 or ≥ 75; asthma, chronic obstructive pulmonary disease, heart disease, or diabetes; pregnancy) suggested that approximately one third of the Canadian population is more susceptible, while inclusive criteria (restrictive plus age 10–19 and 65–74, outdoor work, less than high school education, low vitamin C intake) increased this proportion to approximately two thirds. Across health regions, estimates ranged from 24.4% to 41.2% (restrictive) and 61.2% to 87.0% (inclusive). Ten health regions were in the highest quartile of both population susceptibility and O3 or PM2.5 concentrations, all of which were outside major urban centres.ConclusionsA substantial proportion of the Canadian population exhibits at least one risk factor that increases their susceptibility to adverse effects of O3 and PM2.5 exposure. Both risk communication and management interventions need to be increasingly targeted to regions outside large urban centres in the highest quartiles of both susceptibility and exposure.

Association of PM2.5 with diabetes, asthma, and high blood pressure incidence in Canada: A spatiotemporal analysis of the impacts of the energy generation and fuel sales.

Numerous studies have reported an association between fine particulate matter (PM2.5) and human health. Often these relationships are influenced by environmental factor that varies spatially and/or temporally. To our knowledge, there are no studies in Canada that have considered energy generation and fuel sales as PM2.5 effects modifiers. Determining exposure and disease-specific risk factors over space and time is crucial for disease prevention and control. In this study, we evaluated the association of PM2.5 with diabetes, asthma, and High Blood Pressure (HBP) incidence in Canada. Then we explored the impact of the energy generation and fuel sales on association changes. We fit an age-period-cohort as the study design, and we applied an over-dispersed Poisson regression model to estimate the risk. We conducted a sensitivity analysis to explore the impact of variation in clean energy rates and fuel sales on outcomes changes. The study included 117 health regions in Canada between 2007 and 2014. Our findings showed strong association of PM2.5 with diabetes, asthma, and HBP incidence. A two-year increase of 10μg/m3 in PM2.5 was associated with an increased risk of 5.34% (95% CI: 2.28%; 12.53%) in diabetes incidence, 2.24% (95% CI: 0.93%; 5.38%) in asthma incidence, and 8.29% (95% CI: 3.44%; 19.98%) in HBP incidence. Our sensitivity analysis findings suggest higher risks of diabetes, asthma and HBP incidence when there is low clean energy generation. On the other hand, we found lower risk when we considered high rate of clean energy generation. For example, considering only diabetes incidence, we found that the risk in health regions with low rates of clean electricity is approximately 700% higher than the risk in health regions with high rates of clean electricity. Furthermore, our analysis suggested that the risk in regions with low fuel sales is 66% lower than the risk is health regions with low rates of clean electricity. Our study provides support for the creation of effective environmental health public policies that take into account the risk factors present in Canadians health regions.

Impact of an Innovative Smartphone “App” on Intensive Care Unit (ICU) Antimicrobial Utilization Across a Large Metropolitan Health Region in Canada: An Interrupted Time Series Analysis

Impact of an Innovative Smartphone “App” on Intensive Care Unit (ICU) Antimicrobial Utilization Across a Large Metropolitan Health Region in Canada: An Interrupted Time Series Analysis

How Can Health System Efficiency Be Improved in Canada?

Improving value for money in the health system is an often-stated policy goal. This study is the first to systematically measure the efficiency of health regions in Canada in producing health gains with their available resources, and to identify the factors that are associated with increased efficiency. Based on the objective elicited from decision-makers that the health system should ensure access to care for Canadians when they need it, we measured the efficiency with which regions reduce causes of death that are amenable to healthcare interventions using a linear programming approach (data envelopment analysis). Variations in efficiency were explained in part by public health factors, such as the prevalence of obesity and smoking in the population; in part by characteristics of the population, such as their average income; and in part by managerial factors, such as hospital readmissions.

A Spatial Econometric Analysis of Adult Obesity: Evidence from Canada

This paper examines spatial pattern of adult obesity in Canada from 2000/01 to 2009/10, and analyzes factors associated with obesity and body mass index (BMI). The analysis is based on a panel data set constructed at the health region (HR) level using five confidential Canadian Community Health Surveys. We found that obesity rates are not distributed randomly across HRs in Canada (Moran’s I, 2000/01: 0.501 and 2009/10: 0.659 [p < 0.001]). Therefore, accounting for the spatial pattern of obesity was necessary in order to obtain reliable parameter estimates from regression analyses. We estimated the random- and fixed-effects specifications for the spatial autoregressive and spatial error models. The Hausman specification tests suggested that the fixed-effects models were preferred to that of the random-effects models. The results showed that the proportions of immigrants and homeowners are inversely related to BMI and obesity, while household income, fruits & vegetables consumption, physical activity and smoking are negatively related to BMI. These findings highlight the importance of socioeconomic and behavioural factors affecting adult obesity in Canada even after spatial heterogeneity was accounted for. Thus, a comprehensive and multi-faceted strategy is required to combat adult obesity in Canada.

Socioeconomic Health Disparities in Canadian Regions

Purpose:Numerous studies have estimated health disparities along socioeconomic dimensions using individual data from sample surveys. Disparities between communities or regions cannot be estimated without a consistent set of individual data across communities. This study uses data at the health region level to estimate the socioeconomic health disparitiesbetweenhealth regions in Canada.Methods:Tow measures of income and a measure of education are used for regional socioeconomic ranking along with several health outcomes such as life expectancies, mortality rates, perceived health and obesity. Weighted regressionanalysis is used to estimate the relative inequality index (RII) between Canadian health regions.Results:The findings of the study indicate the existence of health disparities between Canadian health regions along the three socioeconomic markers of average income, median household income and education in favor of regions with higher socioeconomic ranking on those markers. Disparities are more pronounced along the education and average income dimensions, however. Greater inequalities are observed for premature mortality, avoidable mortality and obesity, which are higher for women than men.Conclusion:There are health disparities between Canadian health regions along education and income dimensions. Such disparities signify the role of socioeconomic factors as important instruments in reducing health disparities.

Low pertussis toxin antibody levels in two regional cohorts of Canadian pregnant women

Infants under 6 months of age are at greatest risk of mortality and severe morbidity from pertussis disease. Interventions that increase pertussis protection in newborns are therefore a clear public health imperative. The objective of this study was to assess maternal pertussis toxin antibody (anti-PT) level as a potential source of mother-to-child transfer of pertussis-associated antibodies that may reduce neonatal risk of pertussis disease.Anti-PT level was assessed in a 2013 cohort of pregnant women from two regions in two Canadian provinces, British Columbia and Nova Scotia. Basic demographics, health, and pertussis immunization history were collected, along with blood specimens. Anti-PT levels were compared for self-reported vaccination status and prior pertussis disease. To assess secular trend, a parallel analysis was also undertaken, using anonymized residual sera from a 1996–1997 cohort of pregnant women in British Columbia.A total of 169 pregnant women participated in the study – 50 from Nova Scotia and 119 from British Columbia. The mean and median age of participants from both sites was 31 years of age (range 16–42 years). The lower limit of quantification of the anti-PT assay was 10 ELISA units per milliliter (EU/ml). Overall, 59% of women had anti-PT levels less than 10EU/ml and anti-PT level did not differ with time since last self-reported pertussis vaccination (χ2(2)=3.166, p=0.205). Among a 1996–1997 cohort of pregnant women in British Columbia, 101 of 200 (51%) had anti-PT levels less than 10EU/ml.Our study found that most pregnant women in two geographically disparate health regions in Canada have low residual anti-PT levels, may be vulnerable to pertussis infection themselves, and would unlikely be a source of passive ante- or postnatal transfer of anti-PT to their newborn.

Geographic variation in radon and associated lung cancer risk in Canada.

Radon is an important risk factor for lung cancer. Here we use maps of the geographic variation in radon to estimate the lung cancer risk associated with living in high radon areas of Canada. Geographic variation in radon was estimated using two mapping methods. The first used a Health Canada survey of 14,000 residential radon measurements aggregated to health regions, and the second, radon risk areas previously estimated from geology, sediment geochemistry and aerial gamma-ray spectrometry. Lung cancer risk associated with living in these radon areas was examined using a population-based case-control study of 2,390 lung cancer cases and 3,507 controls collected from 1994-1997 in eight Canadian provinces. Residential histories over a 20-year period were used in combination with the two mapping methods to estimate ecological radon exposures. Hierarchical logistic regression analyses were used to estimate odds ratios for lung cancer incidence, after adjusting for a comprehensive set of individual and geographic covariates. Across health regions in Canada, significant variation in average residential radon concentrations (range: 16-386 Bq/m3) and in high geological-based radon areas (range: 0-100%) is present. In multivariate models, a 50 Bq/m3 increase in average health region radon was associated with a 7% (95% CI: -6-21%) increase in the odds of lung cancer. For every 10 years that individuals lived in high radon geological areas, the odds of lung cancer increased by 11% (95% CI: 1-23%). These findings provide further evidence that radon is an important risk factor for lung cancer and that risks are unevenly distributed across Canada.