Quality control for spirometry in large epidemiologic studies: "breathing quality" into our work.

Spirometry is a time-honored, invaluable measurement for assessing lung function in individuals with chronic obstructive pulmonary disease (COPD) as well as for studying populations with COPD in epidemiologic studies.1,2 Indeed, the prognostic value of spirometry has been appreciated since the 1960s,3 and forced expiratory volume in the first second (FEV1) was more recently included in more comprehensive, multivariate prognostic indices for COPD (eg, the BODE index [body mass index, airflow obstruction, dyspnea, and exercise capacity]4). Also, spirometry has been an early, longstanding, and key measurement in assessing the natural history of lung function in population studies. For example, in 1977 Fletcher and Peto studied FEV1 changes in London transit workers to determine the impact of cigarette smoking on lung function.5