The prevalence of obstructive lung disease in a general population sample: The NICECOPD study

Background: There are little data available on the prevalence of chronic obstructive pulmonary disease (COPD) in the United Kingdom. The Northern Ireland Cost and Epidemiology of Chronic Obstructive Pulmonary Disease (NICECOPD) study is a two-stage survey to examine the prevalence of obstructive lung disease in a general population sample in the Greater Belfast area. Methods: In stage one 4000 subjects aged 40–69 years were selected at random from the general population. They were posted a short screening questionnaire concerning respiratory symptoms. Respondents were divided into ‚symptomatic’ and ‚asymptomatic’ groups according to their responses. In stage two, a sample of symptomatic and asymptomatic subjects completed a more intensive assessment that included a detailed questionnaire on medical history, spirometry, skin allergy testing and serial peak flow measurements. Spirometric criteria for airflow obstruction were FEV1/FVC ratio of