Extreme heat in US associated with increased risk of hospitalization among older adults

December 23, 2014

Between 1999 and 2010, periods of extreme heat in the U.S. were associated with an increased risk of hospitalization for older adults for fluid and electrolyte disorders, kidney failure, urinary tract infections, septicemia and heat stroke, according to a study in the December 24/31 issue of JAMA. The authors note that the absolute risk increase was small and of uncertain clinical importance.

Extreme heat is the most common cause of severe weather fatalities in the United States, and these weather-related outcomes are expected to escalate as heat waves become more frequent, more intense, and longer lasting with climate change. Although extreme heat is known to adversely affect multiple physiological processes, previous studies of the health effects have examined only a few major categories of health outcomes, such as cardiovascular and respiratory diseases or well-known heat-related diseases, such as heat stroke or dehydration, according to background information in the article.

Jennifer F. Bobb, Ph.D., of the Harvard School of Public Health, Boston, and colleagues used Medicare inpatient claims data to systematically examine possible ways in which exposure to heat waves might be associated with serious illness requiring hospitalization in older adults. The study included hospital admissions of Medicare enrollees (23.7 million fee-for-service beneficiaries [65 years of age or older] per year; 85 percent of all Medicare enrollees) for the period 1999 to 2010 in 1,943 counties in the United States, along with at least five summers of near-complete (>95 percent) daily temperature data. Heat wave periods, defined as two or more consecutive days with temperatures exceeding the 99th percentile of county-specific daily temperatures, were matched to non-heat wave periods by county and week.

Of 214 disease groups that accounted for 99.9% of hospitalizations, 5 diseases (fluid and electrolyte disorders, renal [kidney] failure, urinary tract infections, heat stroke, and septicemia [body-wide illness with toxicity due to invasion of the bloodstream by bacteria usually coming from a localized site of infection]) had statistically significantly elevated risk of hospitalization during heat wave days. These risks were larger when the heat wave periods were longer and more extreme and were largest on the heat wave day but remained elevated and statistically significant for 1 to 5 subsequent days.

Absolute risk differences were 0.34 excess daily admissions per 100,000 individuals at risk for fluid and electrolyte disorders, 0.25 for renal failure, 0.24 for urinary tract infections, 0.21 for septicemia, and 0.16 for heat stroke.

The researchers write that their analysis of hospitalization rates on days after a heat wave provides 2 additional insights. "For some diseases, risk of hospitalization remained elevated for up to 5 days following a heat wave day. This suggests that prevention and treatment of heat-related illnesses is critical not only during the heat wave itself but also on subsequent days. Additionally, quantifying the extra number of hospital admissions attributable to heat waves without consideration of a delayed effect may underestimate the health care burden of heat."
(doi:10.1001/jama.2014.15715; Available pre-embargo to the media at http://media.jamanetwork.com)

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

The JAMA Network Journals

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.