Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: The HEI Experience and What's Next?

Although concentrations of ambient air pollution continue to decline in high-income regions, epidemiological studies document adverse health effects at levels below current standards in many countries. The Health Effects Institute (HEI) recently completed a comprehensive research initiative to investigate the health effects of long-term exposure to low levels of air pollution in the United States (U.S.), Canada, and Europe. We provide an overview and synthesis of the results of this initiative along with other key research, the strengths and limitations of the research, and remaining research needs. The three studies funded through the HEI initiative estimated the effects of long-term ambient exposure to fine particulate matter (PM2.5), nitrogen dioxide, ozone, and other pollutants on a broad range of health outcomes, including cause-specific mortality and cardiovascular and respiratory morbidity. To ensure high quality research and comparability across studies, HEI worked actively with the study teams and engaged independent expert panels for project oversight and review. All three studies documented positive associations between mortality and exposure to PM2.5 below the U.S. National Ambient Air Quality Standards and current and proposed European Union limit values. Furthermore, the studies observed nonthreshold linear (U.S.), or supra-linear (Canada and Europe) exposure-response functions for PM2.5 and mortality. Heterogeneity was found in both the magnitude and shape of this association within and across studies. Strengths of the studies included the large populations (7-69 million), state-of-the-art exposure assessment methods, and thorough statistical analyses that applied novel methods. Future work is needed to better understand potential sources of heterogeneity in the findings across studies and regions. Other areas of future work include the changing and evolving nature of PM components and sources, including wildfires, and the role of indoor environments. This research initiative provided important new evidence of the adverse effects of long-term exposures to low levels of air pollution at and below current standards, suggesting that further reductions could yield larger benefits than previously anticipated.

Does urban greenness reduce loneliness and social isolation among Canadians? A cross-sectional study of middle-aged and older adults of the Canadian Longitudinal Study on Aging (CLSA).

OBJECTIVES: Urban greenness has been shown to confer many health benefits including reduced risks of chronic disease, depression, anxiety, and, in a limited number of studies, loneliness. In this first Canadian study on this topic, we investigated associations between residential surrounding greenness and loneliness and social isolation among older adults. METHODS: This cross-sectional analysis of the Canadian Longitudinal Study on Aging included 26,811 urban participants between 45 and 86 years of age. The Normalized Difference Vegetation Index (NDVI), a measure of greenness, was assigned to participants' residential addresses using a buffer distance of 500 m. We evaluated associations between the NDVI and (i) self-reported loneliness using the Center for Epidemiological Studies Depression Scale, (ii) whether participants reported "feeling lonely living in the local area", and (iii) social isolation. Logistic regression models were used to characterize associations between greenness and loneliness/social isolation while adjusting for individual socio-economic and health behaviours. RESULTS: Overall, 10.8% of participants perceived being lonely, while 6.5% reported "feeling lonely in their local area". Furthermore, 16.2% of participants were characterized as being socially isolated. In adjusted models, we observed no statistically significant difference (odds ratio (OR) = 0.99; 95% confidence interval (CI) 0.93-1.04) in self-reported loneliness in relation to an interquartile range (IQR) increase of NDVI (0.06). However, for the same change in greenness, there was a 15% (OR = 0.85; 95% CI 0.72-0.99) reduced risk for participants who strongly agreed with "feeling lonely living in the local area". For social isolation, for an IQR increase in the NDVI, we observed a 7% (OR = 0.93; 95% CI 0.88-0.97) reduction in prevalence. CONCLUSION: Our findings suggest that urban greenness plays a role in reducing loneliness and social isolation among Canadian urbanites.

RéSUMé: OBJECTIFS: Il est démontré que la verdure urbaine confère de nombreux avantages pour la santé; elle réduit notamment les risques de maladies chroniques, de dépression et d'anxiété et, selon un petit nombre d'études, le risque de solitude. Dans cette première étude canadienne sur le sujet, nous avons étudié les associations entre la verdure de l'environnement résidentiel et la solitude et l'isolement social chez les adultes d'âge mûr. MéTHODE: Cette analyse transversale de l'Étude longitudinale canadienne sur le vieillissement a inclus 26 811 participantes et participants urbains de 45 à 86 ans. L'indice de végétation par différence normalisée (IVDN), un indicateur de verdure, a été assigné à l'adresse domiciliaire dans une zone tampon de 500 m. Nous avons évalué les associations entre l'IVDN et i) la solitude autodéclarée selon l'échelle de dépression du Center for Epidemiological Studies, ii) le fait de déclarer « vivre de la solitude dans sa zone locale ¼ et iii) l'isolement social. Des modèles de régression logistique ont servi à caractériser les associations entre la verdure et la solitude/l'isolement social, et nous avons apporté des ajustements pour tenir compte du statut socioéconomique et des comportements de santé individuels. RéSULTATS: Globalement, 10,8 % des participantes et des participants se sentaient seuls, et 6,5 % disaient « vivre de la solitude dans leur zone locale ¼. De plus, 16,2 % des participantes et des participants ont été caractérisés comme étant socialement isolés. Dans nos modèles ajustés, nous n'avons observé aucun écart significatif (rapport de cotes (RC) = 0,99; IC de 95 % : 0,93­1,04) dans la solitude autodéclarée en lien avec une augmentation de l'écart interquartile (EI) de l'IVDN (0,06). Cependant, pour le même changement dans la verdure, la probabilité pour les participantes et les participants d'être tout à fait d'accord avec l'énoncé qu'ils « vivent de la solitude dans leur zone locale ¼ était réduite de 15 % (RC = 0,85, IC de 95 % : 0,72­0,99). Et pour chaque augmentation de l'EI de l'IVDN, nous avons observé une baisse de 7 % (RC = 0,93, IC de 95 % : 0,88­0,97) de la prévalence de l'isolement social. CONCLUSION: Nos constatations indiquent que la verdure urbaine joue un rôle dans la réduction de la solitude et de l'isolement social chez les citadins et citadines au Canada.

Individual physical activity, neighbourhood active living environment and mental illness hospitalisation among adults with cardiometabolic disease: a Canadian population-based cohort analysis.

OBJECTIVES: This population-based observational study explores the associations between individual-level and neighbourhood-level indices of active living with inpatient mental healthcare use among adults with an underlying chronic cardiometabolic condition. DESIGN AND SETTING: Data from the 2013-2014 Canadian Community Health Survey were linked longitudinally to hospital records from the 2013/2014‒2017/2018 Discharge Abstract Database and to a geocoded measure of active living environments (ALE). Relationships between individuals' leisure-time physical activity and neighbourhood ALE with risk of hospital admission for mental health disorders were assessed using multivariable Cox regressions. PARTICIPANTS: A national cohort was identified from the survey data of 24 960 respondents aged 35 years and above reporting having been diagnosed with diabetes, hypertension and/or heart disease. OUTCOME MEASURE: Potentially avoidable hospitalisation for a mood, anxiety or substance use disorder over a 5-year period. RESULTS: More than half (52%) of adults aged 35 years and above with a cardiometabolic disease were physically inactive in their daily lives, and one-third (34%) resided in the least activity-friendly neighbourhoods. The rate of being hospitalised at least once for a comorbid mental disorder averaged 8.1 (95% CI: 7.0 to 9.3) per 1000 person-years of exposure. Individuals who were at least moderately active were half as likely to be hospitalised for a comorbid mental health problem compared with those who were inactive (HR: 0.50 (95% CI: 0.38 to 0.65)). No statistically discernible associations between neighbourhood ALE and hospitalisation risks were found after controlling for individuals' behaviours and characteristics, including in separate models stratified by age group and by sex. CONCLUSIONS: The evidence base to support prioritisation of interventions focusing on the built environment favouring mental health-promoting physical activity among higher-risk adults at the population level, independently of individual-level behaviours and characteristics, remains limited.

The role of neighbourhood environments in hospitalization risk for diabetes and related conditions: A population-based cohort analysis by remoteness and deprivation indices.

Background: Most socio-epidemiological studies on diabetes incidence, prevalence, or hospitalization focus on individual-level risk factors. This population-based cohort study sought to advance understanding on the associations of contextual characteristics and risk of diabetes-related avoidable hospitalization (DRAH) among at-risk Canadians. Data and methods: A national cohort was compiled from the 2013/2014 Canadian Community Health Survey, representing 5.1 million adults aged 35 years and older, reporting having been diagnosed with diabetes, hypertension, or heart disease. Their information was linked longitudinally to hospitalization data from the 2013/14 to 2017/18 Discharge Abstract Database as well as to measures of geographic variability from the Material and Social Deprivation Index and the Index of Remoteness. Cox regression models were used to examine associations between the contextual indices and first occurrence of a DRAH. Results: Residents in the most rural and remote communities were 50% more likely (hazard ratio (HR): 1.51, 95% confidence interval (95% CI): 1.26 to 1.80) to experience a DRAH than those in the most urbanized and accessible communities, and residents in the most socially deprived areas were significantly more likely (HR: 1.44, 95% CI: 1.26 to 1.65) to be hospitalized than those in the most socially privileged areas, controlling for individuals' sociodemographic characteristics and health behaviours. Neighbourhood material deprivation did not exercise a statistically significant influence on hospitalization risk after adjusting for the other residential characteristics. Interpretation: There is a clear and significant gradient in diabetes-related hospitalization risk among Canadians with an underlying cardiometabolic condition by degree of residential remoteness and of neighbourhood social deprivation, independently of individual characteristics and despite Canada's universal healthcare system.

Spatial modeling of ambient concentrations of volatile organic compounds in Montreal, Canada.

Volatile organic compounds (VOCs) are components of the complex mixture of air pollutants within cities and can cause various adverse health effects. Therefore, it is necessary to understand their spatial distribution for exposure assessment in epidemiological studies. Objectives: The objective was to model measured concentrations of five VOCs within the city of Montreal, Canada, developing spatial prediction models that can be used in health studies. Methods: We measured concentrations using 3M 3500 Organic Vapor Monitors, over 2-week periods, for three monitoring campaigns between 2005 and 2006 in over 130 locations in the city. Using GC/MSD (Gas Chromatography/Mass Selective Detector), we measured concentrations of benzene, n-decane, ethylbenzene, hexane, and trimethylbenzene. We fitted four different models that combine land-use regression and geostatistical methods to account for the potential spatial structure that remains after accounting for the land-use variables. The fitted models also accounted for possible variations in the concentration of air pollutants across campaigns. Results: The highest concentrations for all VOCs were found in December with hexane being the most abundant followed by ethylbenzene. We obtained predicted surfaces for the VOCs for the three campaigns and mean surfaces across campaigns. We found higher concentrations of some VOCs along highways and in the Eastern part of Montreal, which is a highly industrialized area. Conclusions: Each of the fitted models captured the spatial and across-campaigns variability for each VOC, and we found that different VOCs required different model structures.

How low can you go? Air pollution affects mortality at very low levels.

The World Health Organization (WHO) recently released new guidelines for outdoor fine particulate air pollution (PM2.5) recommending an annual average concentration of 5 µg/m3. Yet, our understanding of the concentration-response relationship between outdoor PM2.5 and mortality in this range of near-background concentrations remains incomplete. To address this uncertainty, we conducted a population-based cohort study of 7.1 million adults in one of the world's lowest exposure environments. Our findings reveal a supralinear concentration-response relationship between outdoor PM2.5 and mortality at very low (<5 µg/m3) concentrations. Our updated global concentration-response function incorporating this new information suggests an additional 1.5 million deaths globally attributable to outdoor PM2.5 annually compared to previous estimates. The global health benefits of meeting the new WHO guideline for outdoor PM2.5 are greater than previously assumed and indicate a need for continued reductions in outdoor air pollution around the world.

The Impact of Rural Hospital Closures and Health Service Restructuring on Provincial- and Community-Level Patterns of Hospital Admissions in New Brunswick.

In the early 2000s, the Province of New Brunswick, Canada, undertook health system restructuring, including closing some rural hospitals. We examined whether changes in geographic access to hospitals and primary care were associated with changes in patterns of hospital use. We described three measures of hospital use for ambulatory care sensitive conditions (ACSCs) among adults 75 years and younger annually during the period 2004-2013 overall, and at the community scale. We described spatial and temporal patterns in: age-standardized hospitalization rates, age-standardized incidence of hospital admissions, and rates of admissions via ambulance. Overall, rates and incidence of hospitalizations for ACSCs declined while admissions via ambulance remained largely unchanged. We observed considerable regional variation in rates between communities in 2004. This regional variation decreased over time, with rural areas demonstrating the sharpest declines. Changes in hospital service provision within individual communities had little impact on rates of ACSC admissions. Results were consistent across urban and rural communities and were robust to analyses that included older patients and those admitted for reasons other than ACSCs. Our results suggest that the restructuring and hospital closures did not result in substantial changes to regional patterns or rates of service use.

Neighbourhood characteristics related to mental health service use among adults with diabetes: a population-based cohort study in New Brunswick, Canada.

OBJECTIVE: It has been postulated that social and economic inequalities may shape the distributions of comorbid diabetes and mental illness. This observational cohort study using linked population-based administrative and geospatial datasets aimed to describe associations between neighbourhood socioenvironments and disorder-specific mental health service use among adults with diabetes in the province of New Brunswick, Canada. RESULTS: A baseline cohort of 66,275 persons aged 19 and over living with diabetes was identified. One-quarter (26.3%) had used healthcare services for mood and anxiety disorders at least once during the six-year follow-up period 2012/2013-2017/2018. Based on Cox proportional hazards models, the risk of mental health service contacts was significantly higher among those residing in the most materially deprived neighbourhoods [HR: 1.07 (95% CI: 1.01-1.14)] compared to those in the least so, and those in areas characterized with the highest residential instability [HR: 1.13 (95% CI: 1.05-1.22)] compared to those in areas with the lowest instability. Among adults with incident diabetes (N = 4410), age and sex but not neighbourhood factors were related to differential help-seeking behaviours for mental health problems. These findings underscored the gap between theoretical postulations and population-based observations in delineating the syndemics of neighbourhood socioenvironments and mental health outcomes in populations with high diabetes prevalence.

Neighbourhood walkability and mortality: Findings from a 15-year follow-up of a nationally representative cohort of Canadian adults in urban areas.

BACKGROUND: Using a nationally representative cohort of Canadian adults, we assessed associations between neighbourhood walkability and cause-specific mortality and investigated whether they differed by socioeconomic status. METHODS: The study population was drawn from the 2001 Canadian Census Health and Environment Cohort, which contains individual-level data from a random sample of 20% of Canadian households mandated to complete the long-form census. We included those aged ≥ 25 years at baseline who lived in urban and suburban areas. The national death registry was used to ascertain annual vital status. Linkages to annual income tax data provided place of residence. The Canadian Active Living Environments, a national index that summarizes walkability across Canadian neighbourhoods, was assigned to individuals' residential history. The Cox proportional hazards model was used to assess associations between walkability and cause-specific mortality. RESULTS: A total of 1.8 million participants (52.5% female) accrued 27.3 million person-years and 265 710 deaths during the 15-year follow-up. The adjusted hazard ratio (HR) for living in a highly walkable neighbourhood relative to living in the least walkable neighbourhoods was associated with a 9% (HR: 0.91 [0.88, 0.95]) and 3% (HR: 0.97 [0.94, 0.99]) reduced risk of cardiovascular and all non-accidental mortality, respectively. The strongest benefits of walkability were found among individuals within the lowest education and household income categories, and who lived in the most deprived neighbourhoods. There were no significant associations (most [class 5] versus least [class 1] walkable HR: 0.84 [0.61-1.16]) seen for accidental traffic mortality. CONCLUSIONS: Canadian adults who live in walkable neighbourhoods have lower rates of cardiovascular and non-accidental mortality, with the greatest benefits seen in those from the lowest socioeconomic groups.

The influence of outdoor PM2.5 concentration at workplace on nonaccidental mortality estimates in a Canadian census-based cohort.

BACKGROUND: Associations between mortality and exposure to ambient air pollution are usually explored using concentrations of residential outdoor fine particulate matter (PM2.5) to estimate individual exposure. Such studies all have an important limitation in that they do not capture data on individual mobility throughout the day to areas where concentrations may be substantially different, leading to possible exposure misclassification. We examine the possible role of outdoor PM2.5 concentrations at work for a large population-based mortality cohort. METHODS: Using the 2001 Canadian Census Health and Environment Cohort (CanCHEC), we created a time-weighted average that incorporates employment hours worked in the past week and outdoor PM2.5 concentration at work and home. We used a Cox proportional hazard model with a 15-year follow-up (2001 to 2016) to explore whether inclusion of workplace estimates had an impact on hazard ratios for mortality for this cohort. RESULTS: Hazard ratios relying on outdoor PM2.5 concentration at home were not significantly different from those using a time-weighted estimate, for the full cohort, nor for those who commute to a regular workplace. When exploring cohort subgroups according to neighborhood type and commute distance, there was a notable but insignificant change in risk of nonaccidental death for those living in car-oriented neighborhoods, and with commutes greater than 10 km. CONCLUSIONS: Risk analyses performed with large cohorts in low-pollution environments do not seem to be biased if relying solely on outdoor PM2.5 concentrations at home to estimate exposure.

Gendering Neighbourhood Marginalization Metrics in Mental Health Services Research: A Cross-Sectional Exploration of a Rural and Small Urban Population.

Background: Little is known about the extent to which socioenvironmental characteristics may influence mental health outcomes in smaller population centres or differently among women and men. This study used a gender-based analysis approach to explore individual- and neighbourhood-level sex differences in mental health service use in a context of uniquely smaller urban and rural settlements. Methods: This cross-sectional analysis leveraged multiple person-based administrative health datasets linked with geospatial datasets among the population aged 1 and over in the province of New Brunswick, Canada. We used multinomial logistic regression to examine associations between neighbourhood characteristics with risk of service contacts for mood and anxiety disorders in 2015/2016, characterizing the areal measures among all residents (gender neutral) and by males and females separately (gender specific), and controlling for age group. Results: Among the province's 707,575 eligible residents, 10.7% (females: 14.0%; males: 7.3%) used mental health services in the year of observation. In models adjusted for gender-neutral neighbourhood characteristics, service contacts were significantly more likely among persons residing in the most materially deprived areas compared with the least (OR = 1.09 [95% CI: 1.05-1.12]); when stratified by individuals' sex, the risk pattern held for females (OR = 1.13 [95% CI: 1.09-1.17]) but not males (OR = 1.00 [95% CI: 0.96-1.05]). Residence in the most female-specific materially deprived neighbourhoods was independently associated with higher risk of mental health service use among individual females (OR = 1.08 [95% CI: 1.02-1.14]) but not among males (OR = 1.02 [95% CI: 0.95-1.10]). Conclusion: These findings emphasize that research needs to better integrate sex and gender in contextual measures aiming to inform community interventions and neighbourhood designs, notably in small urban and rural settings, to reduce socioeconomic inequalities in the burden of mental disorders.

Ethnocultural and socioeconomic disparities in exposure to residential greenness within urban Canada.

BACKGROUND: Residential greenness has been associated with health benefits, such as lower risk of mortality, cardiovascular disease, obesity, adverse birth outcomes and asthma and better psychological health. However, the variation in greenness across socioeconomic and demographic characteristics in urban areas of Canada has not been well documented. DATA AND METHODS: Respondents to the 2016 Census long-form questionnaire were assigned estimates of exposure to residential greenness based on the mean Normalized Difference Vegetation Index (NDVI) (from 2012 or the most recent year available) within a 500 m buffer around their home, based on postal code. Census weights were used to determine differences in average exposure to greenness according to selected demographic and socioeconomic characteristics. RESULTS: Mean residential greenness among the 5.3 million census respondents in urban Canada was 0.44 units of the NDVI (standard deviation = 0.18 units). Greenness was lower among immigrants (particularly recent immigrants), some groups designated as visible minorities (particularly people of Filipino ancestry), lower-income households and tenants (i.e., NDVI values ranging from 0.40 to 0.43 units). Greenness values were highest among White non-immigrants and higher-income households (i.e., NDVI values ranging from 0.46 to 0.47 units). DISCUSSION: Given the potentially multifaceted role that greenness plays in health outcomes, the inequalities in residential greenness described here may contribute to producing or exacerbating existing health inequalities in the Canadian population.

Neighbourhood environments and the risk of hospital admission for cardiometabolic and mental health comorbidities in multiple sclerosis: A population cohort analysis using linked administrative data.

This study exploits administrative data for neuroepidemiological research and examines associations between neighbourhood environments and risk of hospitalization among multiple sclerosis (MS) patients in New Brunswick, Canada. We created a provincial database of MS patients by linking administrative health records with geographic-based characteristics of local communities. Using Cox models, we found the risk of admission for cardiometabolic complications was lower among residents of ethnically homogeneous neighbourhoods (hazards ratio [HR]: 0.75 [95% confidence interval (CI): 0.60-0.95]); that for mental health disorders was higher in socioeconomically deprived (HR: 1.80 [95% CI: 1.06-3.05]) and residentially unstable (HR: 1.61 [95% CI: 1.05-2.46]) neighbourhoods. Results suggest that selected neighbourhood environments may be associated with differential hospital burden among MS patients.

Residential greenness and indicators of stress and mental well-being in a Canadian national-level survey.

BACKGROUND: Residential proximity to greenness in urban areas has been shown to confer a number of health benefits, including improved mental health. We investigated whether greenness was associated with self-reported stress, distress, and mental health among adult participants of multiple cycles of a national Canadian health survey, and whether these associations varied by sex, age, income, and neighbourhood characteristics. METHODS: Our study population included 397,900 participants of the Canadian Community Health Survey, 18 years of age or older, who lived in census metropolitan areas between 2000 and 2015. We used the Normalized Difference Vegetation Index (NDVI) to characterize participants' exposure to greenness within 250 m, 500 m, and 1 km buffers from a representative location of their postal code. Health outcomes included: self-reported perceptions of life stress, psychological distress, and self-rated mental health. We used multiple regression models, adjusted for relevant individual and neighbourhood-level variables to estimate associations (and 95% confidence intervals) between each outcome and exposure to greenness. FINDINGS: In models with all participants, we observed 6% lower odds of poor self-rated mental health per increase in the interquartile range (i.e., 0.12) of NDVI within a 500 m buffer. Across the three outcomes, we found substantial heterogeneity in effect size across categories of sex, age, and community-level indicators of deprivation and urban form. For example, each incremental increase in greenness exposure was associated with a reduction of 0.61 (95% CI: 0.81 to -0.51) on the K10 psychological distress score among those living in the active core of cities, and with an increase of 0.07 (95% CI: 0.03-0.12) on this score among those living in the most suburban areas. CONCLUSIONS: Our results indicate that the potential benefits of residential greenness on mental health vary across personal and neighbourhood-level characteristics and are sensitive to how the outcome is measured. Additional research is needed to understand which features of greenness are most relevant to different sub-groups of the population to maximize these health benefits.

Residential Greenspace in Childhood Reduces Risk of Pediatric Inflammatory Bowel Disease: A Population-Based Cohort Study.

INTRODUCTION: Environmental factors related to urbanization and industrialization are believed to be involved in inflammatory bowel disease (IBD) development, but no study has looked at the association between greenspace and IBD. METHODS: We conducted a retrospective cohort study using linked population-based health administrative and environmental data sets. The study population comprised 2,715,318 mother-infant pairs from hospital births in Ontario, Canada, between April 1, 1991, and March 31, 2014. We measured the exposure to residential greenspace using the normalized difference vegetation index derived using remote-sensing methods. Average greenspace was estimated for the pregnancy and childhood periods. We used mixed-effects Cox proportional hazard models to assess potential associations between residential greenspace and the risk of developing IBD before 18 years while adjusting for covariates including sex, maternal IBD, rural/urban residence at birth, and neighborhood income. RESULTS: There were 3,444 IBD diagnoses that occurred during follow-up. An increase in the interquartile range of residential greenspace during the childhood period was associated with a lower risk of developing pediatric-onset IBD (hazard ratio [HR] 0.77, 95% confidence interval [CI] 0.74-0.81). This relationship was significant for both ulcerative colitis (HR 0.72 95% CI 0.67-0.78) and Crohn's disease (HR 0.81, 95% CI 0.76-0.87). There was a linear dose response across increasing quartiles of greenspace (P < 0.0001). No consistent association was detected between maternal intrapartum greenspace exposure and pediatric-onset IBD. DISCUSSION: Higher exposure to residential greenspace during childhood was associated with a reduced risk of IBD, suggesting a novel avenue to prevent IBD in children.

Provider caseload volume and short-term outcomes following colorectal surgeries in New Brunswick: a provincial-level cohort study.

BACKGROUND: American studies have shown that higher provider and hospital volumes are associated with reduced risk of mortality following colorectal surgical interventions. Evidence from Canada is limited, and to our knowledge only a single study has considered outcomes other than death. We describe associations between provider surgical volume and all-cause mortality and postoperative complications following colorectal surgical interventions in New Brunswick. METHODS: We used hospital discharge abstracts linked to vital statistics, the provincial cancer registry and patient registry data. We considered all admissions for colorectal surgeries from 2007 through 2013. We used logistic regression to identify odds of dying and odds of complications (from any of anastomosis leak, unplanned colostomy, intra-abdominal sepsis or pneumonia) within 30 days of discharge from hospital according to provider volume (i.e., total interventions performed over the preceding 2 years) adjusted for personal, contextual, provider and hospital characteristics. RESULTS: Overall, 9170 interventions were performed by 125 providers across 18 hospitals. We found decreased odds of experiencing a complication following colorectal surgery per increment of 10 interventions performed per year (odds ratio 0.94, 95% confidence interval 0.91-0.96). We found no associations with mortality. Associations remained consistent across models restricted to cancer patients or to interventions performed by general surgeons and across models that also considered overall hospital volumes. CONCLUSION: Our results suggest that increased caseloads are associated with reduced odds of complications, but not with all-cause mortality, following colorectal surgery in New Brunswick. We also found no evidence of volume having differential effects on outcomes from colon and rectal procedures.

CONTEXTE: Des études américaines ont montré que le volume d'activité des chirurgiens et des hôpitaux est inversement proportionnel au risque de mortalité après la chirurgie colorectale. Les données pour le Canada sont limitées, et à notre connaissance, une seule étude a porté sur d'autres paramètres que le décès. Nous avons décrit les liens entre volume d'activité des chirurgiens et mortalité de toute cause/complications postopératoires après la chirurgie colorectale au Nouveau-Brunswick. MÉTHODES: Nous avons utilisé les registres de congés des hôpitaux reliés aux données de la Statistique de l'état civil, du registre provincial du cancer et du registre des patients. Nous avons recensé toutes les admissions pour chirurgie colorectale de 2007 à 2013. Nous avons utilisé la régression logistique pour établir le risque de décès et le risque de complications (fuite anastomotique, colostomie non planifiée, infection intra-abdominale ou pneumonie) dans les 30 jours suivant le congé de l'hôpital par rapport au volume d'activité des chirurgiens (c.-à-d., interventions totales des 2 années précédentes) ajusté en fonction des caractéristiques individuelles et contextuelles, propres aux chirurgiens et aux hôpitaux. RÉSULTATS: En tout, 125 chirurgiens ont effectué 9170 interventions dans 18 hôpitaux. Nous avons observé un risque moindre de complications après la chirurgie colorectale pour chaque palier de 10 interventions effectuées annuellement (risque relatif 0,94, intervalle de confiance de 95 %, 0,91­0,96). Nous n'avons observé aucun lien avec la mortalité. Les liens sont demeurés constants, peu importe que les modèles soient restreints aux patients cancéreux ou aux interventions effectuées par des chirurgiens généraux et entre les modèles qui tenaient également compte du volume global d'activité des hôpitaux. CONCLUSION: Selon nos résultats, l'augmentation du volume d'activité est associée à un risque moindre de complications, mais n'a pas de lien avec la mortalité de toute cause après la chirurgie colorectale au Nouveau-Brunswick. Nous n'avons pas non plus constaté de lien entre le volume d'activité et l'issue différentielle de la chirurgie du côlon et du rectum.

Residential Greenness and Cardiovascular Disease Incidence, Readmission, and Mortality.

BACKGROUND: Living in greener areas of cities was linked to increased physical activity levels, improved mental well-being, and lowered harmful environmental exposures, all of which may affect human health. However, whether living in greener areas may be associated with lower risk of cardiovascular disease incidence, progression, and premature mortality is unclear. OBJECTIVES: We conducted a cohort study to examine the associations between residential green spaces and the incidence of acute myocardial infarction (AMI) and heart failure (HF), post-AMI and HF hospital readmissions, and mortality. METHODS: We simultaneously followed four large population-based cohorts in Ontario, Canada, including the entire adult population, adults free of AMI and HF, and survivors of AMI or HF from 2000 to 2014. We estimated residential exposure to green spaces using satellite-derived observations and ascertained health outcomes using validated disease registries. We estimated the associations using spatial random-effects Cox proportional hazards models. We conducted various sensitivity analyses, including further adjusting for property values and performing exploratory mediation analysis. RESULTS: Each interquartile range increase in residential greenness was associated with a 7% [95% confidence interval (CI): 4%, 9%] decrease in incident AMI and a 6% (95% CI: 4%, 7%) decrease in incident HF. Residential greenness was linked to a ∼10% decrease in cardiovascular mortality in both adults free of AMI and HF and the entire adult population. These associations remained consistent in sensitivity analyses and were accentuated among younger adults. Additionally, we estimated that the decreases in AMI and HF incidence associated with residential greenness explained ∼53% of the protective association between residential greenness and cardiovascular mortality. Conversely, residential greenness was not associated with any delay in readmission or mortality among AMI and HF patients. CONCLUSIONS: Living in urban areas with more green spaces was associated with improved cardiovascular health in people free of AMI and HF but not among individuals who have already developed these conditions. https://doi.org/10.1289/EHP6161.

Healthcare Service Use for Mood and Anxiety Disorders Following Acute Myocardial Infarction: A Cohort Study of the Role of Neighbourhood Socioenvironmental Characteristics in a Largely Rural Population.

Depression and other mood and anxiety disorders are recognized as common complications following cardiac events. Some studies report poorer cardiac outcomes among patients in socioeconomically marginalized neighbourhoods. This study aimed to describe associations between socioeconomic and built environment characteristics of neighbourhood environments and mental health service contacts following an acute myocardial infarction (AMI or heart attack) among adults in the province of New Brunswick, Canada. This province is characterized largely by residents in small towns and rural areas. A cohort of all adults aged 45 and over surviving AMI and without a recent record of mental disorders was identified by linking provincial medical-administrative datasets. Residential histories were tracked over time to assign neighbourhood measures of marginalization, local climate zones, and physical activity friendliness (i.e., walkability). Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of healthcare use for mood and anxiety disorders over the period 2003/04-2015/16 by neighbourhood characteristics. The baseline cohort included 13,330 post-AMI patients, among whom 32.5% were found to have used healthcare services for a diagnosed mood or anxiety disorder at least once during the period of observation. Among men, an increased risk of mental health service use was found among those living in areas characterized by high ethnic concentration (HR: 1.14 (95%CI: 1.03-1.25)). Among women, the risk was significantly higher among those in materially deprived neighbourhoods (HR: 1.16 (95%CI: 1.01-1.33)). We found no convincing evidence of associations between this outcome and the other neighbourhood characteristics considered here. These results suggest that selected features of neighbourhood environments may increase the burden on the healthcare system for mental health comorbidities among adults with cardiovascular disease. Further research is needed to understand the differing needs of socioeconomically marginalized populations to improve mental health outcomes following an acute cardiac event, specifically in the context of smaller and rural communities and of universal healthcare coverage.

Urban green space and the risks of dementia and stroke.

INTRODUCTION: It is unknown whether urban green space is associated with reduced risk of major neurological conditions, especially dementia and stroke. METHODS: Retrospective, population-based cohorts were created for each study outcome, including 1.7 and 4.3 million adults in Ontario, Canada for dementia and stroke, respectively. Residential green space was quantified using the satellite-derived Normalized Difference Vegetation Index. Incidence was ascertained using health administrative data with validated algorithms. Mixed-effects Cox models were used to estimate hazard ratios per interquartile range increase in green space exposure. RESULTS: Between 2001 and 2013, 219,013 individuals were diagnosed with dementia and 89,958 had a stroke. The hazard ratio per interquartile range increase in green space was 0.97 (95% CI: 0.96-0.98) for dementia and 0.96 (0.95-0.98) for stroke. Estimates remained generally consistent in sensitivity analyses. DISCUSSION: Increased exposure to urban green space was associated with reduced incidence of dementia and stroke. To our knowledge, this is the first population-based cohort study to assess these relationships.

Provider volume and maternal complications after Caesarean section: results from a population-based study.

BACKGROUND: A large literature search suggests a relationship between hospital/surgeon caseload volume and surgical complications. In this study, we describe associations between post-operative maternal complications following Caesarean section and provider caseload volume, provider years since graduation, and provider specialization, while adjusting for hospital volumes and patient characteristics. METHODS: Our analysis is based on population-based discharge abstract data for the period of April 2004 to March 2014, linked to patient and physician universal coverage registry data. We consider all hospital admissions (N = 20,914) in New Brunswick, Canada, where a Caesarean Section surgery was recorded, as identified by a Canadian Classification of Health Intervention code of 5.MD.60.XX. We ran logistic regression models to identify the odds of occurrence of post-surgical complications during the hospital stay. RESULTS: Roughly 2.6% of admissions had at least one of the following groups of complications: disseminated intravascular coagulation, postpartum sepsis, postpartum hemorrhage, and postpartum infection. The likelihood of complication was negatively associated with provider volume and provider years of experience, and positively associated with having a specialization other than maternal-fetal medicine or obstetrics and gynecology. CONCLUSIONS: Our results suggest that measures of physician training and experience are associated with the likelihood of Caesarean Section complications. In the context of a rural province deciding on the number of rural hospitals to keep open, this suggests a trade off between the benefits of increased volume versus the increased travel time for patients.