Heat Exposure and Emergency Department Visits for Sepsis in Phoenix, Arizona Open Access

Abstract

Purpose: As climate change and global warming continues, the frequency and severity of extreme heat events are likely to increase. High heat can lead to death and severe illnesses requiring emergency care. Sepsis is initially diagnosed and treated in emergency departments (EDs). Little is known about the potential impact of outdoor temperatures on risk of sepsis. To address this gap, we assessed the association between heat exposure and emergency department (ED) visits for sepsis patients in Phoenix, Arizona during 2016-2019.

Methods: We examined daily counts of ED visits for patients with a diagnosis of sepsis present on arrival at the ED and assessed focus of infection (FOI) sites for sepsis-related visits, using diagnosis code information. We estimated associations of these outcomes with daily population-weighted average (PWA) temperature exposure data from Daymet using Poisson time-series analysis. We controlled for long term time trends, vapor pressure as a proxy of dewpoint temperature, day of week, and federal holidays. We estimated rate ratios (RRs) and 95% confidence intervals (CI) for the primary model determining the association between sepsis-related ED visits and PWA maximum temperature. In secondary models, we assessed associations of sepsis-related ED visits for each focus of infection site and PWA maximum temperature, and estimated season-specific associations.

Results: In overall year-round models, we observed a positive association between same-day PWA maximum temperature and sepsis-related ED visits (RR of 1.014 95% CI (1.000 – 1.028) for a 5 degree increase in temperature from 24 – 29 degrees C). When stratifying by FOI-specific ED visits, associations of same-day maximum temperature and ED visits for sepsis infections at urogenital sites were positive. Associations were strongest for warm seasons, including Spring, Summer, and Autumn.

Conclusions: Results of this study suggest that outdoor heat exposure may be an important risk factor for sepsis, during the warm season and for urogenital-based infections. Exposure mitigation measures during times of high heat may reduce emergency care needs. Increases in emergency department preparedness during times of high heat may be needed to ensure positive outcomes for patients.

Table of Contents

 

Introduction ................................................................................................................................... 1

 

Study Design .................................................................................................................................. 2

 

1.    Emergency Department Visit Data Collection ................................................................. 2

 

2.    Meteorology Data .......................................................................................................... 4

 

3.    Statistical Methods/Analysis .......................................................................................... 5

 

Results ........................................................................................................................................... 6

 

4.    Descriptive Analysis Results ........................................................................................... 6

 

5.    Main Model Results ....................................................................................................... 8

 

6.    Secondary Analysis Results ............................................................................................ 9

 

Discussion ..................................................................................................................................... 14

 

Conclusion .................................................................................................................................... 18

 

References ..................................................................................................................................... 19

About this Master's Thesis

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School	Rollins School of Public Health
Department	Environmental Health
Degree	M.S.P.H.
Submission	Master's Thesis
Language	English
Research Field	Environmental Health Health Sciences, Epidemiology Climate Change
Keyword	Seasonality Heat exposure Climate Sepsis Focus of infection
Committee Chair / Thesis Advisor	Ebelt, Stefanie, Emory University

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