Heatstroke in temperate zones can be dangerous

By Megan Rauscher

NEW YORK (Reuters Health) - Based on data for patients hospitalized for heatstroke in Lyon, France, during the August 2003 heat wave, it appears that heatstroke is associated with poor patient outcomes in temperate urban areas. "This could be explained at least in part by our lack of experience," researchers note in the Archives of Internal Medicine.

"Classic heatstroke is the most severe heat-related illness," first author Dr. Laurent Argaud of Hospices Civils de Lyon and University Claude Bernard Lyon I noted in comments to Reuters Health. "The clinical course of heat stroke in urban areas of temperate countries is poorly documented."

Argaud and colleagues analyzed survival rates and outcomes for 83 patients (average age, 79.6 years) who were seen at a Lyon hospital for heatstroke during the 2003 heat wave that resulted in some 14,800 heat-related deaths in France.

The researchers found that over a 28-day and 2-year period, the mortality rates were 58 percent and 71 percent, respectively.

The patient's fever level and number of affected organ systems at admission influenced the overall mortality, according to the researchers.

Further analysis revealed that patients most likely to die more often came from an institution for the elderly (24 of 48 non-survivors vs. 7 of 35 survivors) and were more likely to have used antihypertensive medications long-term (33 of 48 who died versus 13 of 35 who survived).

Non-survivors, compared to survivors, also had a higher average body temperature on hospital admission (41.3 degrees Celsius/106.3 degrees Fahrenheit compared with 40.7 degrees Celsius/105.3 degrees Fahrenheit).

"We can speculate that providing aggressive cooling to patients with high risk of death at admission could improve the prognosis in the future," Argaud said.

The people who died were also more likely to have respiratory, cardiovascular or kidney dysfunction and to arrive at the hospital unable to urinate or in a coma.

Most surviving heatstroke victims exhibited a "dramatic alteration" in their functional status at 1 and 2 years, the investigators found.

"Climate models suggest that both the frequency and intensity of heat waves are almost certain to increase in temperate areas," Argaud warned, adding that Western temperate countries need to be more prepared for future heat waves.

SOURCE: Archives of Internal Medicine, November 12, 2007.