Eugene, OR—Pharmacists hear it all the time: Patients on medication for respiratory illnesses complain that their condition worsens when severe thunderstorms are predicted and occur.

Is that just an old saw or is it true?

A new study in JAMA Internal Medicine points outs out that, not only does that seem to be the case, but that thunderstorm-related atmospheric changes are expected to increase in severity with rising global temperatures, so the problem might get worse.

“Although large-scale evidence is limited, vulnerable populations, such as older adults or those with common chronic respiratory diseases, like asthma or chronic obstructive pulmonary disease (COPD), are expected to be susceptible to negative health effects from these changes,” write authors of the University of Oregon–led study.

Researchers sought to determine whether increases in emergency department (ED) visits for acute respiratory illnesses occur among Medicare beneficiaries in the days before, during, and after thunderstorms in the continental United States.

To do that, the study team used publicly available atmospheric and lightning data from the U.S. National Oceanic and Atmospheric Administration covering all 3,127 counties in the continental U.S. from January 1999 to December 2012. That information was combined with insurance claims and comorbidity data from Medicare fee-for-service beneficiaries older than age 65 years to identify all ED visits with acute respiratory diagnoses.

Among more than 46 million Medicare beneficiaries, the mean (SD) age was 77.0 (7.4) years and more than half, 58.6%, were women. Slightly more than 10% had a chronic diagnosis of asthma, while 26.5% had chronic obstructive pulmonary disease and 6.6% had both asthma and COPD.

Researchers identified 22 million respiratory ED visits and 822, 095 county days with major thunderstorms, defined by lightning, precipitation, and above-median wind speed.

Results indicate that thunderstorms were associated with rises in temperature and particulate matter before the storm, followed by declining levels on the day of and the days following the storm. The study points out that pollen counts and levels of nitrogen dioxide, ozone, sulfur dioxide, and carbon monoxide were unchanged until dropping after the storm.

The authors describe how above-baseline ED visits peaked the day before major storms, with a mean 1.8 additional visits per million beneficiaries overall (95% CI, 1.4-2.1), 6.3 for those with asthma (95% CI, 4.1-8.6), 6.4 for those with COPD (95% CI, 5.0-7.8), and 9.4 for those with asthma and COPD (95% CI, 6.2-12.7), corresponding to increases of 1.2%, 1.1%, 1.2%, and 1.2%, respectively.

Overall, they add, in the 3 or more days surrounding the storms, there were 5.3 (95% CI, 3.8-6.8) additional visits per million beneficiaries overall, 22.6 (95% CI, 16.0-29.2) for patients with asthma, 22.4 (95% CI, 17.4-27.4) for those with COPD, and 33.8 (95% CI, 24.0-43.6) for those with both.

“Assuming an average 65 years or older population of 37.7 million Americans (based on census data), approximately 52, 000 additional respiratory ED visits were estimated to occur in the 3 or more days surrounding major storms during the 14-year study period,” the authors conclude.

Researchers suggest that one limitation of their study is that, because of the older study group, it might not generalize to younger populations for which allergic asthma is common.

“To our knowledge, this is the first large-scale study to evaluate the association between thunderstorms and emergency visits for respiratory illness,” according to the report. “Our findings suggest antecedent rises in particulate matter concentration and temperature may be the dominant mechanism of thunderstorm-associated acute respiratory disease in older Americans, which may contribute to strain on the health care system as storm activity increases with rising global temperatures.”

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