Abstract
Background Impulse oscillometry (IOS) allows an effort-independent evaluation of small airway function in asthma. Unfortunately, well-determined minimal clinically important differences (MCID) for IOS-measures are lacking. Here, we provide MCIDs for frequently used IOS-measures, namely frequency dependence of resistance (FDR) and area of reactance (AX) in patients with asthma.
Methods We performed IOS at baseline and 1 year later in adult patients with mild to severe asthma (n=235). In a two-step approach, we first applied a distribution-based method to statistically determine the MCID. Next, we validated the proposed MCID according to patient-reported outcome measures (PROMs) of Asthma Quality of Life Questionnaire (AQLQ), Asthma Control Questionnaire (ACQ) and Asthma Control Test (ACT). We used multivariable analyses to investigate the proposed MCIDs as predictors for improvements in PROMs in comparison to the established MCID of FEV1.
Results The proposed MCID was a decline of≥0.06 kPa·L−1·s−1 and≥0.65 kPa·L−1 for FDR and AX, respectively. Patients who had changes beyond the MCID for both FDR and AX showed greater improvements in all PROMs than those who had not. The mean improvements in PROMs were beyond the established MCID for ACQ and AQLQ and approximated the MCID for ACT score. Multivariable analyses demonstrated the MCID for both FDR and AX as independent predictors for the MCID of all PROMs. The MCID for FDR was a stronger predictor of all PROMs than the MCID for FEV1.
Conclusion This study provides MCIDs for IOS-derived measures in adult patients with asthma and emphasizes that small airway function is a distinguished endpoint beyond the conventional measure of FEV1.
Footnotes
This manuscript has recently been accepted for publication in the European Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article.
Conflicts of interest: Mustafa Abdo received travel support from Chiesi and consulting fees from AstraZeneca, all outside the submitted work.
Conflicts of interest: Anne-Marie Kirsten reports no relevant conflicts of interest.
Conflicts of interest: E. von Mutius reports personal fees from Pharmaventures, OM Pharma S. A., Springer-Verlag GmbH, Elsevier GmbH and Elsevier Ltd., Peptinnovate Ltd., Turun Yliopisto, Tampereen Yliopisto, Helsingin Yliopisto, European Respiratory Society, Deutsche Pharmazeutische Gesellschaft e. V., Massachusetts Medical Society, Chinese University of Hongkong, Böhringer Ingelheim, ProtectImmun GmbH. Faculteit Diergeneeskunde, Universität Salzburg, Georg Thieme Verlag, and Japanese Society of Pediatric Allergy and Clinical Immunology, and Universiteit Utrecht, all outside the submitted work.
Conflicts of interest: Matthias Kopp and Gesine Hansen report no relevant conflicts of interest.
Conflicts of interest: Klaus F. Rabe reports grants from Boehringer Ingelheim and Astra Zeneca as well as personal fees from Boehringer Ingelheim and Astra Zeneca, personal fees from Novartis, Roche, Chiesi Pharmaceuticals, Regeneron, Sanofi and Berlin Chemie.
Conflicts of interest: Henrik Watz reports no relevant conflicts of interest.
Conflicts of interest: Frederik Trinkmann received travel support from Actelion, Berlin Chemie, Boehringer Ingelheim, Chiesi, Novartis, Mundipharma, TEVA AstraZeneca, Berlin Chemie, Boehringer Ingelheim, Bristol-Myers Squibb, Chiesi, GlaxoSmithKline, Novartis and Roche, and Sanofi-Aventis, all outside the submitted work.
Conflicts of interest: Thomas Bahmer reports grants from BMBF: Unrestricted research grant for the German Center for Lung Research (DZL), during the conduct of the study; and personal fees from AstraZeneca, GlaxoSmithKline, Novartis, and Roche, outside the submitted work.
- Received September 14, 2022.
- Accepted January 26, 2023.
- Copyright ©The authors 2023. For reproduction rights and permissions contact permissions{at}ersnet.org
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