3.0 Results
3.1 Description
There were 1649 deaths during the EHE (25 June – July 02, 2021) and
6700 deaths during the typical weather period (25 June – July 02,
2012-2020). We included 1614 EHE deaths and 6524 typical weather deaths
after omitting 67 children (8 EHE; 59 typical weather), 95 deaths with
missing location data (12 EHE; 83 typical weather), and 49 deaths with
missing demographic information (15 EHE; 34 typical weather). During the
EHE, there were 280 heat-related deaths (X30), 382 deaths with
information still pending from BCCS (R99), and 952 non-heat-related
deaths (not X30 or R99, Figure 3). More detailed information on cause of
death for the entire study population is available in the supplementary
materials (Figure S1). The mean annual number (range) of typical weather
deaths was 725 (618-824). One typical weather death had extreme heat
(X30) as the underlying cause, and 129 (2-50 per year) had an unknown or
pending (R99) cause of death.
Overall, the age and sex distributions of the EHE and typical weather
deaths were similar. The EHE group had higher proportions of decedents
with schizophrenia, chronic kidney disease, diabetes, and depression
than the typical weather group, as well as a higher total number of
chronic diseases. The EHE group also had lower proportions of decedents
with angina, dementia, and osteoporosis. Within the EHE group, there
were some clear differences between the heat-related (X30), pending
(R99), and non-heat-related (not X30 or R99) subgroups (Table 1).
We included 21 of the 26 chronic disease registries in conditional
logistic regression. Juvenile arthritis was excluded because no children
were included in this study (juvenile arthritis diagnoses require
patients to be ≤ 15 years old). We removed multiple sclerosis and
hemorrhagic stroke because <1% of EHE decedents had these
conditions. Hospitalized stroke and mood/anxiety disorders were
collinear with ischemic stroke and depression, respectively. All cases
of ischemic stroke (N = 481) were also categorized as hospitalized
stroke (N = 539), and all cases of depression (N = 3557) were also
categorized as mood/anxiety disorder (N = 4124). In both cases, we
excluded the higher-level category (i.e., hospitalized stroke,
mood/anxiety disorder) because the lower-level category (i.e., ischemic
stroke, depression) represented a more specific condition.
Table 1. Descriptive statistics. Demographics and
chronic diseases among the extreme heat event (EHE) deaths and the
typical weather comparison group. The EHE deaths are further subdivided
into heat-related (ICD-10 code X30), pending (ICD-10 code R99), and
non-heat-related subgroups (ICD-10 code not X30 or R99).