Is risk of dying in hospital from respiratory causes higher in the summer than winter?

A recent study conducted by the Barcelona Institute for Global Health (ISGlobal) and published in The Lancet Regional Health - Europe has shed light on how global warming, driven by climate change, could heighten the burden of inpatient mortality from respiratory diseases, particularly during warmer seasons.

The research team embarked on a mission to analyze the relationship between ambient temperature and in-hospital mortality attributed to respiratory diseases. The data uncovered a clear pattern: hospital admissions, including those resulting in death, peaked during the cold season and hit their lowest point during the warm season. Remarkably, while hospital admissions surged during the cold season, the maximum incidence of inpatient mortality occurred during the summer months, strongly correlated with high temperatures.

The study revealed that summer temperatures were linked to a substantial percentage of fatal hospitalizations from respiratory diseases in both Madrid and Barcelona. Significantly, the impact of heat was immediate, with most of the effects occurring within the initial three days of exposure to high temperatures.

The study further noted the effect of heat on acute bronchitis, bronchiolitis, pneumonia, and respiratory failure. Intriguingly, neither relative humidity nor air pollutants played a statistically significant role in the association of heat with mortality among patients admitted for respiratory diseases. Moreover, it was observed that women were more susceptible to the effects of heat than men due to distinct physiological differences in thermoregulation.

Reference: Achebak H, Garcia-Aymerich J, Rey G, Chen Z, Méndez-Turrubiates RF, Ballester J. Ambient temperature and seasonal variation in inpatient mortality from respiratory diseases: a retrospective observational study. Lancet Regional Health - Europe. Oct 2023. 10.1016/j.lanepe.2023.100757