The optimal control frequency of patients with COPD is unknown. COPD is a disease with fluctuating activity and complaints over time. There is a chance that patients are seen at a stable state at the regular outpatient clinical visits instead of moments when medical care is obligated. The regular management of the outpatient clinic will therefore result in an ineffective treatment of COPD patients. In this way general practitioners and even patients could suggest that visits to the outpatient pulmonary clinic are confounding less to a good treatment of COPD.