Heat Waves Might Ignite Health Issues

Heat stroke, septicemia and kidney failure hospitalizations increased in hot weather

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Extreme heat may spark more health problems than just heat stroke.

A new study found that the risk of hospitalization for a number of conditions, such as infection of the bloodstream and kidney failure, increased among older adults during heat waves.

Extreme heat can affect health when the body is unable to properly compensate for hot temperatures and cool itself, explained the Centers for Disease Control and Prevention (CDC). The CDC recommended a number of steps to stay safe during temperatures of extreme heat, such as drinking plenty of water and spending time in cool areas.

"Air-conditioning is the number one protective factor against heat-related illness and death," the CDC reports on its website. "During conditions of extreme heat, spend time in locations with air-conditioning such as shopping malls, public libraries, or public health sponsored heat-relief shelters in your area."

According to the authors of this new study, which was led by Francesca Dominici, PhD, of the Harvard School of Public Health in Boston, while it is known that extreme heat has been tied to health dangers, past studies have mainly focused on issues like heat stroke or heart problems.

Dr. Dominici and colleagues wanted to explore the relationship between extreme heat and hospital admissions for a wide range of conditions.

To do so, they looked at US Medicare data for the years 1999 to 2010. This included around 23.7 million adults aged 65 and older in 1,943 counties across the US.

Dr. Dominici and team obtained weather data from the National Climatic Data Center. These researchers looked at hospital admissions during heat waves — two or more days in a row of very high temperatures for that specific county — and compared the data to times when there was no heat wave.

The risk for hospitalization for several conditions increased somewhat during a heat wave, Dr. Dominici and team found. These conditions included septicemia (a serious condition where an infection has entered the bloodstream) and fluid and electrolyte disorders (which may be tied to dehydration and can affect the body's ability to properly function). However, the risk for congestive heart failure decreased slightly on these days.

Dr. Dominici and colleagues found 0.34 excess hospital admissions a day per 100,000 people at risk for fluid and electrolyte issues, 0.25 extra admissions for kidney failure, 0.24 for urinary tract infections, 0.21 for septicemia and 0.16 for heat stroke.

The risk for hospitalization tended to increase more during longer and more extreme heat waves. Risks were highest on the initial heat wave day but tended to remain at higher-than-normal levels for the following several days.

"By considering all causes of hospitalization rather than prespecifying a small number of individual diseases, our study provides new insights into previously unsuspected possible outcomes associated with heat exposure," Dr. Dominici and colleagues wrote.

This study looked at mostly rural counties and explored an association between heat and these hospitalizations — not necessarily that one caused the other. Further research is needed, these researchers said.

This study was published online Dec. 23 in JAMA.

Grants from a number of different organizations, such as the National Institute of Environmental Health Sciences and the National Cancer Institute, funded this research. The authors disclosed no conflicts of interest.

Review Date: 
December 23, 2014
Last Updated:
December 26, 2014