Extreme heat linked to hospitalizations in children with asthma

According to a study published at the ATS 2024 International Conference, which took place May 17-22 in San Diego, California, extreme hot weather has been linked to increased hospitalizations due to asthma.

“We found that both daily hot days and extreme temperatures over multiple days increased the risk of hospitalizations due to asthma,” said the study's lead author. Morgan Yeh, MPH, is a data analyst in pulmonary and critical care medicine at the University of California, San Francisco School of Medicine.

"Understanding the impact of climate-related events, such as extreme heat, on vulnerable populations is key to reducing the burden of disease caused by climate change."

Ms. Yeh and her colleagues examined electronic health records from 2017 to 2020 from UCSF Benioff Children's Hospital in Oakland, which included data on asthma hospitalizations for hospital patients, some of whom were from Benioff Federally Qualified Health Care Center Oakland, and demographic information, including patient zip codes.

They used data from the PRISM Climate Group at Oregon State University to determine the timing of maximum (daytime heatwaves) and minimum (nighttime heatwaves) temperatures for each zip code. The researchers limited their analyzes to the region's warm season (June to September).

To estimate the potential range of effects of different heat wave measurements, they used 18 different heat wave definitions, including the 99th, 97.5th, and 95th percentiles of the total distribution over the study period of one, two, or three days.

They designed the study to determine the relationship between each heat wave definition and hospitalization. They repeated the analysis for zip codes in the San Francisco Bay Area and Central California.

The team found that daytime heat waves were significantly associated with a 19% increase in the likelihood of hospitalizations in children with asthma, and longer heat waves doubled the likelihood of hospitalizations. Nighttime heat waves showed no associations.

According to Ye, “We continue to see global temperatures rise due to man-made climate change, and we can expect to see more health problems as we see longer, more frequent and more severe heat waves.

"Our research shows that higher temperatures and longer durations of these hot days are associated with an increased risk of hospitalizations due to asthma. Children and families with less adaptive capacity will experience the greatest burden.

"It is therefore important to better understand these heat-related risks and vulnerable populations for future monitoring and targeted interventions."

The authors note that previous studies have suggested positive associations between extreme heat and asthma, but results regarding hospitalizations and emergency department visits have been inconsistent.

In addition, many other studies focused on respiratory hospitalizations, not specifically asthma hospitalizations, and did not include children.

This study is also unique in that it examined the effects of both daily high temperatures and prolonged extreme temperatures.

The San Francisco Bay Area, and California in general, are unique areas of interest because the state is considered a coastal region with less prevalence of cooling systems such as air conditioning. While temperatures may not reach the extremes seen in other parts of the country, this study demonstrates that even moderate extreme temperatures can have significant impacts on health.

These effects are more pronounced in climate-vulnerable populations, including children and those who are medically vulnerable, such as patients at the urban pediatric center involved in the study. The authors hope that the results of this study will lead to more equitable health outcomes and a reduction in racial/ethnic disparities seen in climate-sensitive events.

"These findings can be used to inform targeted interventions and resource allocation for vulnerable children and reduce health-related stress during heat waves," they conclude.