Background and objective: Although the relationship between day-to-day temperature changes and COPD mortality is well established, it is not known whether temperature variation within one day, that is diurnal temperature range (DTR), is a risk factor for acute COPD death, independent of the absolute temperature level.
Methods: In a time-series study, the relationship between DTR and daily COPD mortality between 2001 and 2004 in Shanghai, China was assessed. A semi-parametric generalized additive model was used to allow for long-term and seasonable trends in COPD mortality, as well as variation in air pollution and weather.
Results: There was a significant association between DTR and daily COPD mortality. A 1 degrees C increase in the 4-day moving average for DTR corresponded to a 1.25% (95% confidence interval: 0.35-2.15) increase in COPD mortality.
Conclusion: These findings suggest that DTR is a novel risk factor for acute COPD death.