Arithmetic Behind a Positive Bronchodilator Response.

The critical question as to what constitutes a positive bronchodilator response (BDR) has recently been revisited. 1 Stanojevic S. Kaminsky D.A. Miller M.R. et al. ERS/ATS technical standard on interpretive strategies for routine lung function tests. Eur Respir J. 2022; 602101499 Crossref Scopus (150) Google Scholar Per the 2005 American Thoracic Society/European Respiratory Society (ATS/ERS) recommendations, 2 Miller M.R. Hankinson J. Brusasco V. et al. ATS/ERS Task Force: standardisation of spirometry. Eur Respir J. 2005; 26: 319-338 Crossref PubMed Scopus (11913) Google Scholar , 3 Graham B.L. Steenbruggen I. Miller M.R. et al. Standardization of spirometry 2019 update: an Official American Thoracic Society and European Respiratory Society technical statement. Am J Respir Crit Care Med. 2019; 200: e70-e88 Crossref PubMed Scopus (1376) Google Scholar , 4 Culver B.H. Graham B.L. Coates A.L. et al. Recommendations for a standardized pulmonary function report: an official American Thoracic Society technical statement. Am J Respir Crit Care Med. 2017; 196: 1463-1472 Crossref PubMed Scopus (394) Google Scholar , 5 Pellegrino R. Viegi G. Brusasco V. et al. Interpretative strategies for lung function tests. Eur Respir J. 2005; 26: 948-968 Crossref PubMed Scopus (4350) Google Scholar a BDR (referred here as BDR2005) was considered positive if two criteria were met: (1) an absolute increase in FEV1 or FVC by 200 mL or more, and (2) a relative increase in FEV1 or FVC by 12% or more. 6 Brand P.L. Quanjer P.H. Postma D.S. et al. Interpretation of bronchodilator response in patients with obstructive airways disease: the Dutch chronic non-specific lung disease (CNSLD) Study Group. Thorax. 1992; 47: 429-436 Crossref PubMed Scopus (170) Google Scholar This relative change in volume is referred in this paper as BDRrelative, which can be written, using FEV1 as an example, as follows: BDR relative = ( post FEV 1 − prev FEV 1 ) / pre FEV 1 ( expressed in % , Equation 1 ) where “post” and “pre” refer to post-bronchodilation and pre-bronchodilation, respectively.