Abstract
Background
Heatwaves have been linked to increased risk of mortality and morbidity and are projected
to increase in frequency and intensity due to climate change. The current study uses emergency
department (ED) data from Australia, Botswana, Netherlands, Pakistan, and the
United States of America to evaluate the impact of heatwaves on ED attendances, admissions
and mortality.
Methods
Routinely collected time series data were obtained from 18 hospitals. Two separate thresholds
(4 and 7) of the acclimatisation excess heat index (EHIaccl) were used to define
“hot days”. Analyses included descriptive statistics, independent samples T-tests to determine
differences in case mix between hot days and other days, and threshold regression to
determine which temperature thresholds correspond to large increases in ED attendances.Findings
In all regions, increases in temperature that did not coincide with time to acclimatise resulted
in increases in ED attendances, and the EHIaccl performed in a similar manner. During hot
days in California and The Netherlands, significantly more children ended up in the ED,
while in Pakistan more elderly people attended. Hot days were associated with more patient
admissions in the ages 5–11 in California, 65–74 in Karachi, and 75–84 in The Hague. During
hot days in The Hague, patients with psychiatric symptoms were more likely to die. The current study did not identify a threshold temperature associated with particularly large
increases in ED demand.
Interpretation
The association between heat and ED demand differs between regions. A limitation of the
current study is that it does not consider delayed effects or influences of other environmental
factors. Given the association between heat and ED use, hospitals and governmental
authorities should recognise the demands that heat can place on local health care systems.
These demands differ substantially between regions, with Pakistan being the most heavily
affected within our study sample.