Even short-term exposure to rising temperatures was associated with an increased risk for COPD exacerbations in a newly reported study.
Researchers conducted a time-stratified, case-crossover analysis to explore the association between ambient temperature and COPD exacerbation risk.
After controlling for relative humidity, they found that each one-degree Celsius increase in ambient temperatures was associated with a 2% increased odds of having a COPD exacerbation two days later. While hotter weather has been linked to higher COPD mortality in previous studies, the new analysis is among the first to show an increased risk for disease exacerbations related to rising temperatures.
The findings were presented early this week at the virtual European Respiratory Disease Society International Congress by University of Washington pulmonary and critical care specialist Supaksh Gupta, MD.
“Other studies have shown a connection between extreme heat exposure and increased risk of health problems and death in people with COPD,” Gupta noted in a written press statement. “There are concerns that these problems will accelerate with the ongoing and worsening climate crisis. Therefore, it is important to quantify the health risks associated with changes in ambient temperature, while also determining who is most at risk to inform policy-makers and healthcare providers.”
The time-stratified analysis included 1,177 current and former smokers enrolled between 2010 and 2015 in the observational SubPopulations and InteRmediate Outcome Measures in COPD (SPIROMICS) study.
One aim of the ongoing SPIROMICS study is to examine the biology of COPD exacerbations by exploring predisposing baseline phenotypes, exacerbation triggers and host inflammatory responses.
In previously reported findings involving the cohort, researchers reported that long-term ambient ozone exposure was associated with worse respiratory outcomes and increased emphysema, independent of smoking or workplace exposures in smokers with or at risk for COPD.
All participants included in the newly presented analysis had experienced at least one COPD exacerbation since enrolling in the SPIROMICS study.
Using conditional logistic regression, with local ambient temperature as a continuous variable, Gupta and colleagues assessed the risk of COPD exacerbation based on ambient temperature at lag days 0 to 7.
The mean patient age was 63.7 years [SD 8.6]) and mean time to first exacerbation was 603 days [SD 523].
The analysis revealed that the risk for experiencing an exacerbation was elevated with increased temperatures during the preceding one to six days, with the observed risk peaking at the two-day lag period. After controlling for relative humidity, each one-degree Celsius increase in ambient temperature was significantly associated with 2% increased odds of COPD exacerbation two days following the elevated temperature (P=0.002).
“This study is one of the few to explore the impact of ambient temperature on the risk of COPD exacerbations in a group of people with established COPD for whom we have detailed medical information,” Gupta said. “Overall it contributes to the emerging body of knowledge regarding ambient temperature and risk of COPD-related health problems.”
Gupta noted that major study strengths were its large sample size and diverse geographic population of U.S. residents.
He added that the mechanisms driving heat-related increased risk for COPD exacerbations are not completely understood. One theory is that dynamic hyperinflation, which involves incomplete exhalation and inefficient breathing, could lead to increased pressure in the chest cavity and decreased blood flow to the heart.
Elderly people also have more problems adjusting their body temperatures and maintaining hydration during extremely hot weather, he said.
“Our findings raise concerns about the risk of increased exacerbations with climate change,” Gupta noted. “While not conclusive, the study suggests that those living with COPD may want to avoid exposure to adverse and extreme environmental conditions by limiting outdoor activities during periods of elevated temperatures relative to normal.”
Commenting on the study findings, Zorana Andersen of the University of Copenhagen, who is the chair of the European Respiratory Society Environment and Health Committee noted that the findings add to the urgency of addressing the worsening climate conditions.
“The climate emergency is proving to have far-reaching effects in areas of everyday life where it might not necessarily be expected to have an impact,” Andersen noted. “This study offers a fascinating insight into the way it could be affecting the lives of people living with COPD and is yet more proof of the urgent need to tackle climate change and the world’s rising temperatures.”
Even short-term exposure to rising temperatures was associated with an increased risk for COPD exacerbations.
After controlling for relative humidity, they found that each one-degree Celsius increase in ambient temperatures was associated with a 2% increased odds of having a COPD exacerbation two days later.
Salynn Boyles, Contributing Writer, BreakingMED™
This research was fundted by the U.S. National Health, Lung and Blood Institute and the COPD Foundation. Gupta reported no relevant disclosures related to this research.
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