Temperature effects on outpatient visits of respiratory diseases, asthma, and chronic airway obstruction in Taiwan.

This study evaluated the risk of outpatient visits for respiratory diseases, asthma, and chronic airway obstruction not elsewhere classified (CAO) associated with ambient temperatures and extreme temperature events from 2000 to 2008 in Taiwan. Based on geographical and socioeconomics characteristics, this study divided the whole island into seven areas. A distributed lag non-linear model was used to estimate the area-disease-specific cumulative relative risk (RR), and random-effect meta-analysis was used to estimate the pooled RR of outpatient visits, from lag 0 to lag 7 days, associated with daily temperature, and added effects of prolonged extreme heat and cold for population of all ages, the elderly and younger than 65 years. Pooled analyses showed that younger population had higher outpatient visits for exposing to low temperature of 18 °C, with cumulative 8-day RRs of 1.36 (95% confidence interval (CI) 1.31-1.42) for respiratory diseases, 1.10 (95% CI 1.03-1.18) for asthma, and 1.12 (95% CI 1.02-1.22) for CAO. The elderly was more vulnerable to high temperature of 30 °C with the cumulative 8-day RR of 1.08 (95% CI 1.03-1.13) for CAO. Elevated outpatient visits for all respiratory diseases and asthma were associated with extreme heat lasting for 6 to 8 days. On the contrary, the extreme cold lasting more than 8 days had significant negative association with outpatient visits of all respiratory diseases. In summary, elderly patients of respiratory diseases and CAO are vulnerable to high temperature. Cold temperature is associated with all types of respiratory diseases for younger patients.