Measurement agreement between a portable and a conventional impulse oscillometry system: a two-centre...

Impulse oscillometry (IOS) enables tidal-breathing assessment of airway mechanics and is useful in patients with limited cooperation. With the growing use of portable IOS devices for bedside and community pulmonary function assessment, agreement with established laboratory systems requires evaluation.

To assess measurement agreement and clinical classification agreement between the portable IOS 600 and the conventional Jaeger MasterScreen-IOS.

In this prospective two-centre method-comparison study with randomised measurement-sequence allocation, adult and paediatric participants underwent IOS measurement using both devices during a single visit. Core parameters (respiratory impedance at 5 Hz (Z5), resistance at 5 Hz (R5), resistance at 20 Hz (R20), reactance at 5 Hz (X5), reactance area and resonant frequency (Fres)) and secondary parameters were analysed. Interdevice agreement was assessed using intraclass correlation coefficients (ICCs), Bland-Altman analysis and coefficients of variation. Clinical classification agreement for core parameters was evaluated using Gwet's agreement coefficient 1 (AC1).

Of 200 enrolled participants, 164 were included in the final paired analysis. Core IOS parameters showed high interdevice agreement, with ICCs ranging from 0.902 to 0.961. Bland-Altman analysis demonstrated small mean interdevice differences; however, proportional bias was observed for Z5, R5 and Fres, indicating that agreement at markedly abnormal values should be interpreted cautiously. Coefficients of variation did not differ significantly between devices. Clinical classification agreement was strong to almost perfect, with Gwet's AC1 values of 0.90, 0.92, 0.91 and 0.96 for Z5, R5, R20 and X5, respectively. Adult-only and exploratory disease-subgroup analyses showed generally consistent agreement estimates. Most secondary resistance parameters showed strong-to-almost-perfect agreement, whereas reactance at 15 Hz and reactance at 25 Hz showed lower agreement.

The portable IOS 600 demonstrated high measurement agreement and clinical classification agreement with the MasterScreen-IOS for core IOS parameters under standardised testing conditions. Because the final cohort was predominantly adult, these findings are primarily applicable to adult participants. IOS 600 may serve as a complementary tool for airway function assessment, although further validation is needed in paediatric, disease-specific, bedside, primary care and community settings.