Chronic Diseases Associated With Mortality in British Columbia, Canada During the 2021 Western North America Extreme Heat Event

Abstract

Individual extreme heat events (EHEs) can be associated with hundreds to thousands of excess deaths (Kovats & Hajat, 2008), with the most severe example being the approximately 70,000 excess deaths that occured across Europe during an extended EHE in the summer of 2003(Robine et al., 2008. The frequency and intensity of EHEs are expected to increase in the coming decades because of climate change, and global temperature extremes have already become more frequent since the 1950s (Ebi et al., 2021;IPCC, 2021). Consequently, it is essential to understand who is at risk of dying during EHEs to help develop interventions to prevent future heat-related mortality.Susceptibility to the health effects of high temperatures varies between individuals. For example, older adults have an increased risk of death because thermoregulation and the ability to recognize thermal stimuli deteriorate with age (Ebi et al., 2021;Kenny et al., 2018). Other factors associated with an increased risk include pre-existing cardiovascular disease (Ebi et al., 2021) and mental illness (J. as well as material deprivation (Kovats & Hajat, 2008) and social isolation (Kenny et al., 2019). Age, cardiovascular disease, respiratory disease, and diabetes are often cited as primary risk factors for heat-related illness or death and are generally referenced in public health messaging (

Reflections on a Century of Extreme Heat Event‐Related Mortality Reporting in Canada

“…These characteristics included: people 65 years and older (Henderson, Lamothe, et al., 2022; Semenza et al., 1996); living alone (Gasparrini et al., 2012; Henderson, McLean, et al., 2022); of low‐income (BC Coroners Service, 2022a; Henderson, McLean, et al., 2022); who live in urban heat islands with little to no surrounding greenspace (BC Coroners Service, 2022a; Hauen, 2018; Henderson, McLean, et al., 2022; Kinney et al., 2008); with pre‐existing chronic health conditions (e.g., cardiovascular disease, hypertension, diabetes) (BC Coroners Service, 2022a; Kalkstein & Smoyer, 1993); and, with mental illnesses—namely substance use disorders, anxiety and mood disorders (Table 3) (Chersich et al., 2020; Kalkstein & Smoyer, 1993; Kuehn & McCormick, 2017). This aligns broadly with the populations identified as most‐at‐risk in the literature, with the new insight that people with schizophrenia have died at alarmingly disproportionate rates across several EHEs in Canada (e.g., 2018 Montreal and 2021 BC) (BC Coroners Service, 2022a; D. Kaiser et al., 2019; Lee et al., 2023; Price et al., 2013). Only a few reports provided sex or gender differences in rates of heat‐related death, which limited our ability to identify a pattern (Gan & Henderson, 2019; Henderson, McLean, et al., 2022; Kosatsky et al., 2012).…”

“…To facilitate comparison, such studies could use existing frameworks to analyze heat‐related deaths. More physiological and qualitative studies could also help with better understanding trends that have emerged through epidemiological studies, such as the disproportionately high rates of heat‐related mortality among people with schizophrenia (Cornwall, 2023; D. Kaiser et al., 2019; Lee et al., 2023; Price et al., 2013). Additionally, while this commentary has focused on heat‐related mortality, more attention is also warranted to enhancing reporting for heat‐related morbidity.…”

“…Historically, there have been individual reports and articles describing the populations impacted in past EHEs in Canada. For example, there have been discrete analyses of major EHEs, such as Lee et al.’s (2023) analysis of the prevalence of chronic diseases in decedents of the 2021 BC EHE, and D. Kaiser et al.’s (2019) review of people who died in the 2018 EHE in Montreal. However, there is no known retrospective analysis of populations who died during past EHEs across Canada that span different timeframes (cross‐temporal) and locations (cross‐geographical).…”

Portland’s Response to the Western North American Heatwave: A Brief Report

“…Calculations for nearby British Columbia estimate 740 excess deaths in the province alone. 5 Government agencies in the Portland area were well prepared. The heatwave response drew upon 3 reports that anticipated extreme heat events: the 2015 Oregon Natural Hazards Mitigation Plan, the 2015 Multnomah County Climate Change Action Plan, and the 2017 Multnomah County Natural Hazards Mitigation Plan.…”

Heat Resilience and Severe & Persistent Mental Illness

“…The odds ratio for schizophrenia among all heat event deaths was 3.07. 1 The World Health Organization has called climate change the greatest health threat of this century, and it is already affecting the health of people in Canada. Climate change affects physical health through heat-related illness; flood and wildfire-related deaths and displacement; wildfire-related lung and heart disease; increased tick-borne disease; longer allergy seasons; and increased food insecurity.…”