Method
Study design and participants
This cross-sectional study was conducted in ten general
practices throughout the Netherlands between June 2010
and April 2011. The study sample consisted of COPD patients who attended the participating general practices
and visited the practice nurses during consulting- hours.
The patients included in the study complied with the
following criteria: a diagnosis of mild COPD (GOLD I),
moderate COPD (GOLD II) or severe COPD (GOLD III). The GOLD (Global initiative for chronic Obstructive
Lung Disease) is a classification of severity of airflow limitation in COPD based on post-bronchodilator forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC). Furthermore, they had to be both physically and mentally able to complete the questionnaires. Patients were excluded if they had participated in another study or if they had a primary diagnosis of asthma. The Medical Research Ethics Committee (MREC) of the University Hospital Utrecht concluded that the Medical Research Involving Human Subjects Act (WMO) does not apply to this study; therefore, no WMO approval by the MREC was needed. The MREC ensured that the individuals involved in the study were adequately informed that their data would be used for research proposes. All participants provided written informed consent to participate in the study.