Anxiety and Depression in COPD; Prevalence, Detection and Prognosis

The current cohort study of 300 stable COPD patients aims to assess the following topics: * The prevalence of anxiety and depressive disorders in patients with COPD * The screening properties of Hospital Anxiety and Depression Scale in patients with COPD * The prognostic influence by anxiety or depressive symptoms and anxiety or depressive disorder. * whether characterization of 1) affective aspects of dyspnea symptoms or 2) persistent styles of thinking (worry or rumination) and metacognitions that drive these may improve the current recommendation of screening for anxiety and depression in COPD in relation to its clinical relevance on functional status and three year outcome