Seasonality, ambient temperatures and hospitalizations for acute exacerbation of COPD: a population-based study in a metropolitan area

Almagro, Pere; Hernandez, Carme; Martinez-Cambor, Pable; Tresserras, Ricard; Escarrabill, Joan

The aim of our study was to assess the influence of temperature on the number of hospital admissions for COPD exacerbation in a well-defined geographic area and to assess the influence of humidity, comorbidity, influenza-like illness, and air pollution on these hospitalizations. Given the climate diversity in Catalonia, Spain, and in order to homogenize the sample according to temperature, we selected only those pertaining to Barcelona and its metropolitan area (600 km 2 and 3,000,000 inhabitants) with a homogeneous Mediterranean climate characterized by moderate temperatures with mild winters, hot summers, and a variable climate during spring and autumn. Regions with a Mediterranean climate are found between 31 and 40 degrees latitude north and south of the equator, on the western side of continents, and include areas of southern and southwestern Australia, central Chile, coastal California, the Western Cape of South Africa, and around the Mediterranean Sea. Since the temperature is usually a few degrees higher in the large cities than in the surrounding areas (urban heat island effect), we also compared the number of admissions and temperatures in the city of Barcelona with the rest of the metropolitan area.