Study design and study cohort

The German COPD cohort COSYCONET (German COPD and Systemic Consequences – Comorbidities Network) is a prospective, observational, multicenter cohort study.13 A total of 2,741 subjects were recruited in 31 study centers across Germany between September 2010 and December 2013. After the baseline visit, participants were evaluated in follow-up visits at 6 and 18 months, and further ongoing visits. Data for the present analysis were drawn from the baseline examination (visit 1) and the 18-month follow-up (visit 3). Patients fulfilling enrolment inclusion criteria into the cohort were aged 40 years and older with a physician diagnosis of COPD (according to the GOLD criteria) or chronic bronchitis. Additionally, patients must have had availability for repeated study visits over at least 18 months. Patients were excluded if they experienced any of the following: having undergone major lung surgery (eg, lung volume reduction, lung transplant); moderate or severe exacerbation within the last four weeks; having a lung tumor; physical or cognitive impairment resulting in an inability to walk or understand the intention of the project.