Lung Function Monitoring; A Randomized Agreement Study.

Objective: To determine the agreement between devices and repeatability within devices of the forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF) and forced expiratory flow at 50% of FVC (FEF50) values measured using the four spirometers included in the study.

Methods: 50 (24 women) participants (20-64 years of age) completed maximum forced expiratory flow manoeuvres and measurements were performed using the following devices: MasterScreen, SensorMedics, Oxycon Pro and SpiroUSB. The order of the instruments tested was randomized and blinded for both the participants and the technicians. Re-testing was conducted on a following day within 72 hours at the same time of the day.

Results: The devices which obtained the most comparable values for all lung function variables were SensorMedics and Oxycon Pro, and MasterScreen and SpiroUSB. For FEV1, mean difference was 0.04 L (95% confidence interval; -0.05, 0.14) and 0.00 L (-0.06, 0.06), respectively. When using the criterion of FVC and FEV1 ≤ 0.150 L for acceptable repeatability, 67% of the comparisons of the measured lung function values obtained by the four devices were acceptable. Overall, Oxycon Pro obtained most frequently values of the lung function variables with highest precision as indicated by the coefficients of repeatability (CR), followed by MasterScreen, SensorMedics and SpiroUSB (e.g. min-max CR for FEV1; 0.27-0.46).

Conclusion: The present study confirms that measurements obtained by the same device at different times can be compared; however, measured lung function values may differ depending on spirometers used.