Differences in Impulse Oscillometry Parameters Measured Using Different Devices

Background: Limited data exist regarding both the absolute values and the percentage of predicted values of impulse oscillometry (IOS) when measured using different devices. We aimed to compare IOS values and their percentages of predicted values obtained from the MasterScreen-IOS and the MostGraph-02 in individuals with chronic respiratory diseases. Methods: A retrospective analysis was conducted in subjects with COPD and asthma. IOS measurements were obtained from the same individuals using both the MasterScreen-IOS and the MostGraph-02. Thai reference values, previously derived from MasterScreen-IOS, were used to calculate percent predicted IOS parameters. Paired sample t test was used to compare IOS values derived from the two devices. Correlations between IOS values obtained from the two devices were analyzed using Pearson's correlation and Bland-Altman analysis was employed to determine the limits of agreement between the IOS values derived from these devices. Results: A total of 54 subjects (36 with asthma and 18 with COPD) with a mean age of 65.7 ± 10.8 years, of whom 33 (61.1%) were male, were included. The reactance values, including the absolute values and percent predicted values for resonant frequency (Fres) and the area under the reactance curve between 5 Hz and the resonant frequency (AX), were significantly higher with the MasterScreen-IOS compared with the MostGraph-02. Discrepancies in IOS measurements, particularly in percent predicted values for heterogeneity of resistance between R5 and R20 (R5-R20), Fres, and AX, were observed when comparing the two devices. Conclusion: Significant differences in IOS reactance values were found between the MasterScreen-IOS and MostGraph-02. Device-specific reference equations may contribute to differences in percent predicted values. Therefore, IOS measurements from these devices should be interpreted cautiously and not considered interchangeable for longitudinal assessments.