3.2 Specific chronic diseases
When all EHE deaths were compared with all typical weather deaths, the
OR [95% confidence interval] for those with schizophrenia was 3.07
[2.39, 3.94]. EHE deaths were also significantly increased among
those with chronic kidney disease and ischemic heart disease with ORs of
1.36 [1.18, 1.56] and 1.18 [1.00, 1.38], respectively. The
effect estimates for most chronic diseases were null (Figure 4; Table
S2). However, there were several conditions for which the odds of
mortality were significantly lower among EHE deaths, including angina,
hospitalized transient ischemic attack, dementia, and osteoporosis. For
example, the OR was 0.74 [0.63, 0.87] for dementia and 0.58 [0.47,
0.71] for angina (Figure 4; Table S2).
3.3 Burden of chronic
disease
The odds of EHE mortality were higher among those with more chronic
diseases (Figure 5; Table S3). The ORs were higher than 1.0 for those
with 3 or more chronic diseases, and most were statistically
significant. However, there was no clear trend of increasing ORs with
increasing burden of chronic disease; most estimates for 3 or more
chronic diseases were similar. The ORs were null for those with 1 and 2
chronic diseases.
3.4 Subgroup analysis
3.4.1 Heat-related deaths
When the 280 deaths already classified as heat-related (X30) were
compared with all typical weather deaths, odds of EHE mortality were
significantly increased among those with schizophrenia, chronic kidney
disease, depression, and diabetes (Figure 5A; Table S2). The ORs were
3.99 [2.62, 6.08] for schizophrenia, 1.45 [1.07, 1.96] for
chronic kidney disease, 1.86 [1.42, 2.44] for depression, and 1.42
[1.08, 1.86] for diabetes. The ORs were significantly less than 1.0
for those with angina and dementia. The ORs were increased for those
with 4 or more chronic diseases (Figure 5B; Table S3).
3.4.2 Deaths with pending cause
(R99)
When the 382 deaths with pending cause (R99) were compared with all
typical weather deaths, the odds of death during the EHE were
significantly increased for those with schizophrenia, substance use
disorder, and chronic obstructive pulmonary disease (Figure 5A; Table
S2). The ORs were 4.95 [3.46, 7.09] for schizophrenia, 1.51 [1.14,
2.01] for substance use disorder, and 1.33 [1.01, 1.75] for
chronic obstructive pulmonary disease. The ORs were significantly less
than 1.0 for those with dementia and angina. There was no clear effect
of higher chronic disease burden in this group (Figure 5B; Table S3).
3.4.3 Non-heat-related deaths (not X30 or
R99)
When the 952 non-heat-related (not X30 or R99) deaths were compared with
all typical weather deaths, the odds of EHE mortality were significantly
increased among those with schizophrenia, ischemic stroke, chronic
kidney disease, and ischemic heart disease (Figure 5A; Table S2). The
ORs were 1.66 [1.14, 2.43] for schizophrenia, 1.39 [1.07, 1.80]
for ischemic stroke, 1.39 [1.17, 1.64] for chronic kidney disease,
1.25 [1.03, 1.52], and for ischemic heart disease. The ORs were
significantly decreased among those with angina and osteoporosis, and
generally elevated for those with 6 or more chronic diseases (Figure 5B;
Table S3).