Introduction: Whole-breath oscillometry (OSC) is an effort-independent lung function test obtainable when spirometry is not. Intra-breath OSC (OSCIB), correlates better with symptoms than OSC or spirometry in adult asthma and IPF. The ability of OSCIB to predict COPD symptoms is unknown.
Hypothesis: OSC and OSCIB correlate the COPD Assessment Test (CAT) and the mMRC as strongly as spirometry.
Methods: 158 subjects with CAT, mMRC, biometrics, spirometry, OSC and OSCIB were included and underwent 3-5 measurements of OSC (tremoFlo C-100) yielding resistance (R) and reactance (X) parameters and then a 30-45s OSCIB measurement at 10 Hz yielding 10 Hz X from which novel X vs flow and volume parameters including the end-inspiratory X (XeI) were calculated. Groups included 1.COPD (?10 pack-year, post-bronchodilator FEV1/FVC<0.70), 2.preCOPD (COPD, but post-bronchodilator FEV1/FVC?0.70 and MMEF<65%predicted) and 3.Healthy. Kruskal-Wallis and post-hoc Dunn tests or ?2 tested between group differences, and Bonferroni-corrected Spearman rho, correlation strengths.
Results: Correlations strengths are shown below for 104 COPD, 31 preCOPD and 23 Healthy.
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Conclusion: Spirometry, OSC and OSCIB all demonstrated moderate correlations with CAT and mMRC. Of all parameters, the novel XeI showed the strongest correlation with symptoms. Both OSC and OSCIB may be viable alternatives to spirometry for assessing COPD symptoms.