Effects of ambient temperature on COPD symptoms and exacerbations in the SubPopulations and InteRmediate Outcome Measures In COPD Study (SPIROMICS) cohort

Heat exposures have been associated with increased respiratory mortality in patients with COPD, and there is concern that this problem will accelerate with a warming climate. We examined the association between risk of COPD exacerbations and ambient temperature in preceding days in a well-characterized cohort. We conducted a time-stratified case-crossover analysis of 1177 current and former smokers from SPIROMICS with at least one COPD exacerbation since study enrollment. Using conditional logistic regression, with local ambient temperature as a continuous variable, we assessed the risk of COPD exacerbation based on ambient temperature at lag days 0 to 7. Mean age of participants was 63.7 years [SD 8.6]) and mean time to first exacerbation was 603 days [SD 523]. The risk of exacerbation was elevated for 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, Figure 1). These findings suggest an increased risk of COPD exacerbations approximately 2 days following an increase in ambient temperature, raising concern for increased exacerbation risk with a changing climate.