Parameter D: New measure of airflow obstruction

This study was undertaken to develop diagnostic thresholds for Parameter D, a novel metric for detection of airflow obstruction. Expiratory volume-time curves were calculated based on spirometry data in normal subjects included in the 2007–2008, 2009–2010 and 2011–2012 NHANES cohorts. Relationships between demographics and lung function were subsequently tested using generalized linear models from NHANES and the UK Biobank, with UK Biobank data collected using the Vitalograph Pneumotrac spirometer.