Heat waves are becoming more common, but according to this new study, the number of hospital admissions for heat stroke has declined significantly in the United States in recent years. In one of the largest studies of its kind, researchers examined data from more than 23 million Medicare beneficiaries in 1,916 U.S. counties between 1999-2010. They calculated the relative risk of heat stroke among older adults during heat wave days (defined as at least two consecutive days with daily mean temperature greater than the 97th percentile of temperatures in that county) compared to non-heat wave days. Researchers found that over time, the risk of heat stroke declined, with notable geographic differences. The risk was highest in the Northeast, while it was lower in the South and Southwest. They also found that heat waves early in the summer were more likely to result in heat stroke admissions than those later in the season.
The results of this study were published in Environmental Health and featured in the Harvard Chan School news.