Study Finds Associations Between Extreme Heat and Asthma-Related Hospital Visits in Children

According to research presented at the 2024 American Thoracic Society International Conference, extreme heat events were associated with an increase in asthma-related hospital visits. The study demonstrates that the milder extreme heat temperatures in California, even if they do not meet the extremes of other regions, can significantly impact health in children.¹

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Extreme heat, according to the authors, has previously been associated with adverse health outcomes, particularly in pediatric patients. The study assesses the association between extreme heat and asthma exacerbation—as assessed by hospitalizations—among a pediatric population with asthma who were seeking care at the University of California San Francisco (UCSF) Benioff Children’s Hospital Oakland. The study authors noted that California—particularly the San Francisco Bay Area—were unique and considered an area of interest because the state is a coastal region that has a smaller prevalence of cooling units and air conditioners, according to the authors.^1,2

For this study, the investigators used electronic health record data from Benioff Children’s Hospital. This data included hospital visits due to asthma-related events, patient demographics, and the patients’ zip codes. Additionally, the daily maximum (or daytime heat wave) and minimum (nighttime heat waves) temperatures for each population-weighted centroid of each zip code were gathered. Temperatures gathered were from June to September for each year included in the analysis.²

Further, 18 different heat wave definitions—including where the temperature exceeded the 99th, 97.5th, and 95th percentiles of the total temperature distribution of the study period for 1, 2, or 3 days—were used to evaluate the potential range in effects of different heat wave measurements. The authors designed the study to allow them to determine the association between each heat wave definition and a hospital visit, then they repeated the analysis for the Central California and Bay Area zip codes.^1,2

The findings demonstrated that daytime heat waves were significantly associated with a higher risk of going to the hospital (OR: 1.21; 95% CI: 1.01, 1.45) and (OR: 1.79; 95% CI: 1.07, 2.99) for day 1 in the 95th percentile, and day 3 in the 99th percentile, respectively. Further, there was a positive association between heat and asthma-related hospital visits in the Bay Area (OR: 1.83; 95% CI: 1.08, 3.11); however, no associations were observed in Central California. Additionally, the authors did not observe any associations between nighttime heat waves and hospitalizations.²

“We found that both daily high heat events and extreme temperatures that lasted several days increased the risk of asthma hospital visits,” said corresponding author Morgan Ye, MPH, research data analyst, Division of Pulmonary and Critical Care Medicine, University of California, San Francisco School of Medicine, in a news release. “Understanding the impacts of climate-sensitive events such as extreme heat on a vulnerable population is the key to reducing the burden of disease due to climate change.”¹

Additionally, the authors note that there were conflicting findings regarding hospitalizations and emergency room visits. They also note that the study is unique because no prior research has investigated the effect of daily high temperatures, while also considered the effects of persistent extreme temperatures in a pediatric population with asthma.¹

“We continue to see global temperatures rise due to human-generated climate change, and we can expect a rise in health-related issues as we observe longer, more frequent, and severe heat waves. Our research suggests that higher temperatures and increased duration of these high heat days are associated with increased risk of hospital visits due to asthma. Children and families with lower adaptation capacity will experience most of the burden,” said Ye in the news release. “Therefore, it is important to obtain a better understanding of these heat-associated health risks and susceptible populations for future surveillance and targeted interventions.”¹

The authors note that the findings were more evident in populations more susceptible to the changing climate, such as children or people who are considered more vulnerable medically. According to the authors, the findings from this study can help lead to more equitable health outcomes while reducing racial or ethnic disparities that are often present in climate-sensitive events.¹

“These results can be used to inform targeted actions and resources for vulnerable children and alleviate health-related stress during heat waves,” the authors said in the news release.¹

References

1. American Thoracic Society. Extreme Heat Associated With Children's Asthma Hospital Visits. News release. May 13, 2024. Accessed May 23, 2024. https://www.newswise.com/articles/view/810781/?sc=sphr&xy=10026574

2. Ye, M, Ndovu, A, Nguyen, AV, Long, D, Benmarhnia, T, and Thakur, N. Extreme Heat and Asthma Hospitalizations in Children in California (2017-2020) (abstract). Am J Respir Crit Care Med 2024;209:A2728 doi:10.1164/ajrccm-conference.2024.209.1_MeetingAbstracts.A2728