Ambient heat exposure and COPD hospitalisations in England: a nationwide case-crossover study during 2007-2018

BackgroundThere is emerging evidence suggesting a link between ambient heat exposure and chronic obstructive pulmonary disease (COPD) hospitalisations. Individual and contextual characteristics can affect population vulnerabilities to COPD hospitalisation due to heat exposure. This study quantifies the effect of ambient heat on COPD hospitalisations and examines population vulnerabilities by age, sex, and contextual characteristics.MethodsIndividual data on COPD hospitalisation at high geographical resolution (postcodes) during 2007-2018 in England was retrieved from the small area health statistics unit. Maximum temperature at 1 km×1km resolution was available from the UK Met Office. We employed a case-cross over study design and fitted Bayesian conditional Poisson regression models. We adjusted for relative humidity and national holidays, and examined effect modification by age, sex, green space, average temperature, deprivation and urbanicity.ResultsAfter accounting for confounding, we found a 1.47% (95% Credible Interval 1.19% to 1.73%), increase in the hospitalisation risk for every 1°C increase in temperatures above 23.2°C (lags 0-2 days). We reported weak evidence of an effect modification by sex and age. We found a strong spatial determinant of the COPD hospitalisation risk due to heat exposure, that was alleviated when we accounted for contextual characteristics. 1 851 (95% CrI 1 576 to 2 079) COPD hospitalisations were associated with temperatures above 23.2°C annually.ConclusionOur study suggests that resources should be allocated to support the public health systems, for instance through developing or expanding heat-health alerts, to challenge the increasing future heat-related COPD hospitalisation burden.Key MessagesWhat is the key question?What is the short-term effect of heat exposure on COPD hospitalisation and which contextual/societal factors affect population vulnerability?What is the bottom line?For every 1°C increase in summer temperatures higher than 23.2°C, the risk of COPD hospitalisation increases by 1.47%, and populations in the North and in the South East are more vulnerable.Why read on?This large nationwide study in England using individual data quantifies the effect of heat exposure on COPD hospitalisations; these findings inform future policies regarding preparedness and resilience of public health systems against the increasing COPD burden due to the increasing temperatures.