Usefulness of a compendium of respiratory standard questionnaires for adults (CORSQ).

Questionnaires are the most commonly used subjective instrument of measurement in respiratory epidemiology. The quality of the data collected by questionnaires is quantitatively expressed by validity and reliability, and may be reduced by bias. Validity, expressed as sensitivity and specificity, is assessed by comparing a questionnaire's results with independent measurements, while reliability, expressed as consistency, is measured by the agreement of responses between two administrations of the same questionnaire. Sources of potential bias include the mode of administration (e.g. by interviewer, self-administered), and the questionnaire itself (e.g. wording, back-translation). The standardization of the questionnaire aims at limiting bias, and maximizing validly and reliability. Most of the European and American respiratory standard questionnaires derive from the British Medical Research Council (BMRC) questionnaire, originally developed in the 1950s to investigate the epidemiology of chronic bronchitis and chronic airway obstruction. Among those, the National Heart and Lung Institute (NHLI), the Questionnaire for respiratory diseases recommended by the American Thoracic Society and the Division of Lung Diseases for use in epidemiology research of adults and children (ATS-DLS-78), and the International Union Against Tuberculosis and Lung Diseases (IUATLD) questionnaire are included. Within the Concerted Action on Chronic Obstructive Pulmonary Disease (CA-COPD) a Compendium of Respiratory Standard Questionnaires for adults (CORSQ) was developed, with the purpose of making available a synthetic reference of validated standard questions. The CORSQ, covering 18 topics, from general information to early life events, through respiratory symptoms and diseases, is intended as a reference of existing validated questions, and an example for possible new questions to be used in respiratory epidemiology.