Characterization of circadian COPD symptoms by phenotype: Methodology of the STORICO observational study.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide. The symptoms of COPD are troublesome, variable, can occur during all parts of the 24-h day and have a substantial impact on patients' health status, quality of life and healthcare resource utilization. Reducing symptoms, improving health status and increasing physical activity are major goals in the management of stable COPD.