The relationship between diurnal temperature range and COPD hospital admissions in Changchun, China.

Diurnal temperature range (DTR) has been suggested to be an adverse health factor especially related to respiratory and cardiovascular diseases. In the current study, we investigated the association between DTR and chronic obstructive pulmonary disease (COPD) hospital admissions during 2009 to 2012 in northeast city of Changchun, China. Based on generalized additive model (GAM), the effects were expressed as relative risk (RR) values of COPD with 95% confidence intervals (CIs) with each 1 °C increase in DTR. And they were significantly increased with an increment of 1 °C in DTR, modified by season, age, and sex. The elderly were more vulnerable, with relative risk values of 1.048 (1.029, 1.066) in cold season and 1.037 (1.021, 1.053) in warm season. Regarding the gender, the DTR effect on females was greater during cold season and the RR value was 1.051 (1.033, 1.069) on the current day (lag 0). The greater estimates for males appeared at lag 7 days, with RR of 1.019 (0.998, 1.040). A season-specific effect was detected that the relative risk values with per 1 °C increase in DTR were greater in cold season than in warm season. These findings support the hypothesis of significant relationship between DTR and COPD in Changchun, one northeast city of China.