17 / 2021-06-03 18:29:26

Temperature variability and asthma hospitalisation in Brazil, 2000-2015: A nationwide case-crossover study

Temperature variability,asthma

Background: Both cold and hot temperature have been associated with the onset of asthma, but it remains largely unknown about the risk of asthma hospitalization associated with short-term temperature fluctuation or temperature variability (TV).

Objective: To explore the association between short-term exposure to TV and asthma hospitalization in Brazil.

Methods: Data for asthma hospitalization and weather conditions were collected from 1,816 Brazilian cities between 2000 and 2015. TV was calculated as the standard deviation of all daily minimum and maximum temperatures within 0-7 days prior to current day. A time-stratified case-crossover design was performed to quantify the association between TV and hospitalization for asthma.

Results: A total of 2,818,911 hospitalizations for asthma were identified during the study period. Each 1 ˚C increase in 0–7 days’ TV exposure was related to a 1.0% [95% confidence interval (CI): 0.7–1.4%] increase in asthma hospitalizations. The elderly were more vulnerable to TV than other age groups, while region and season appeared to significantly modify the associations. There were 159,305 (95% CI: 55,293–258,054) hospitalizations, $48.41 million (95% CI: $16.92–$78.30 million) inpatient costs at 2015 price and 450.44 thousand days (95% CI: 156.08–729.91 thousand days) associated with TV during the study period. The fraction of asthma hospitalizations attributable to TV increased from 5.32% in 2000 to 5.88% in 2015.

Conclusion: TV was significantly associated with asthma hospitalization and the corresponding substantial health costs in Brazil. Our findings suggest that preventive measures of asthma should take TV into account.