Abstract
Western North America experienced an unprecedented extreme heat event
(EHE) in 2021, characterized by high temperatures and reduced air
quality. There were approximately 740 excess deaths during the EHE in
the province of British Columbia, making it one of the deadliest weather
events in Canadian history. It is important to understand who is at risk
of death during EHEs so that appropriate public health interventions can
be developed. This study compares 1614 deaths from 25 June – 02 July
2021 with 6524 deaths on the same dates from 2012-2020 to examine
differences in the prevalence of 26 chronic diseases between the two
groups. Conditional logistic regression was used to estimate the odds
ratio (OR) for each chronic disease, adjusted for age, sex, and all
other diseases, and conditioned on geographic area. The OR [95%
confidence interval] for schizophrenia among all EHE deaths was 3.07
[2.39, 3.94], and was larger than the ORs for other conditions.
Chronic kidney disease and ischemic heart disease were also
significantly increased among all EHE deaths, with ORs of 1.36 [1.18,
1.56] and 1.18 [1.00, 1.38], respectively. Chronic diseases
associated with EHE mortality were somewhat different for deaths
attributed to extreme heat, deaths with an unknown/pending cause, and
non-heat-related deaths. Schizophrenia was the only condition associated
with significantly increased odds of EHE mortality in all three
subgroups. These results confirm the role of mental illness in EHE risk
and provide further impetus for interventions that target specific
groups of high-risk individuals based on underlying chronic conditions.