Exacerbations of Chronic Obstructive Pulmonary Disease (COPD): An Ecological Study in the Basque Country, Spain (2000-2011)

Chronic obstructive pulmonary disease (COPD) is a prevalent condition in adults aged ≥40 years characterized by progressive airflow limitation associated with chronic inflammatory response to noxious particles in the airways and lungs. Smoking, genetics, air pollution, nutrition and other factors may influence COPD development. Most hospitalizations and deaths for COPD are caused by its acute exacerbations, which greatly affect the health and quality of life of COPD patients and pose a high burden on health services. The aims of this project were to identify trends, geographic patterns and risk factors for COPD exacerbations, as revealed by hospitalizations and deaths, in the Basque Country, Spain, over a period of 12 years (2000-2011). Hospitalization and mortality rates for COPD were 262 and 18 per 100,000 population, respectively, with clusters around the biggest cities. Hospital mortality was 7.4%. Most hospitalized patients were male (77.4%) and accounted for 72.1% of hospital mortality. Hospitalizations decreased during the study period, except for 50-64 year-old women, peaking significantly. Using a multivariate modeling approach it was shown that hospitalizations were positively correlated with increased atmospheric concentrations of NO2, CO, PM10, and SO2, and increased influenza incidence, but were negatively associated with increased temperatures and atmospheric O3 concentration. COPD exacerbations decreased in the Basque Country during 2000-2011, but not among 50-64-year-old women, reflecting the high smoking prevalence among Spanish women during the 1970-1990s. The main metropolitan areas were those with the highest risk for COPD exacerbations, calling attention to the role of heavy car traffic. Influenza virus, cold temperatures, and increased atmospheric NO2, CO, PM10, and SO2 (but decreased O3) concentrations were identified as potential contributors to the burden of COPD exacerbations in the community. These findings are important for both the understanding of the disease process and in providing potential targets for COPD-reducing initiatives and new avenues for research.