RT Journal Article
SR Electronic
T1 Grading the severity of airways obstruction: new wine in new bottles
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 505
OP 512
DO 10.1183/09031936.00086313
VO 43
IS 2
A1 Philip H. Quanjer
A1 Jeffrey J. Pretto
A1 Danny J. Brazzale
A1 Piotr W. Boros
YR 2014
UL http://erj.ersjournals.com/content/43/2/505.abstract
AB The objective of this study was to redesign the current grading of obstructive lung disease so that it is clinically relevant and free of biases related to age, height, sex and ethnic group. Spirometric records from 17 880 subjects (50.4% female) from hospitals in Australia and Poland, and 21 191 records (53.0% female) from two epidemiological studies (age range 18–95 years) were analysed. We adopted the American Thoracic Society(ATS)/European Respiratory Society (ERS) criteria for airways obstruction based on an forced expiratory volume in 1 s (FEV1)/(forced) vital capacity ((F)VC) ratio below the fifth percentile and graded the severity of pulmonary function impairment using z-scores for FEV1, which signify how many standard deviations a result is from the mean predicted value. Using the lower limit of normal for FEV1/(F)VC and z-scores for FEV1 of -2, -2.5, -3 and -4 to delineate severity grades of airflow limitation leads to close agreement with ATS/ERS severity classifications and removes age, sex and height related bias. The new classification system is simple, easily memorised and clinically valid. It retains previously established associations with clinical outcomes and avoids biases due to the use of per cent predicted FEV1. Combined with the Global Lung Function prediction equations it provides a worldwide diagnostic standard, free of bias due to age, height, sex and ethnic group. Using FEV1 z-scores to classify severity of airways obstruction is clinically valid and overcomes bias inherent in % pred http://ow.ly/pRyGI