Questionnaires and lung function

Questionnaires and lung function testing are important instruments of measurement in respiratory epidemiology.Questionnaires allow the investigation of large population samples through the collection of subjective data. Their basic methodological requirements are validity, reliability and bias. The first standardised respiratory questionnaire was developed by the British Medical Research Council in the 1950s, and was the basis of subsequent questionnaires developed in Europe and the USA. More recently, ad hoc questionnaires for specific studies have been produced, even though existing validated questionnaires still appear to be largely used.Lung function testing has several applications in respiratory epidemiology. Standardised procedures have been developed to minimise variability of lung function testing measurements, and updated reference equations have been derived to improve interpretation of results. Spirometry is the most frequently used test in population-based studies but other tests, including diffusing capacity or methacholine challenge test, have been shown to be applicable in respiratory epidemiology.