Changes in fractional exhaled nitric oxide, forced expiratory volume in one second, and forced oscillation technique parameters over three years in adults with bronchial asthma managed under Yokohama Seibu Hospital’s coordinated care system

Abstract

Abstract Background: In western Yokohama, our hospital and primary care clinics manage adult asthmatics via a coordinated care system. We investigated the changes in the fractional expired nitric oxide (FeNO), forced expiratory volume in 1 second (FEV1), and forced oscillation technique (FOT) parameters over 3 years in a cohort of patients in our collaborative system. Methods: From 288 adults with stable asthma managed under the Yokohama Seibu Hospital coordinated care system between January 2009 and May 2018, we selected 99 subjects to undergo spirometry, FeNO and FOT testing over 3 years and analyzed the changes in these parameters. Results: Of the 99 patients enrolled, 35 (35.3%) experienced exacerbations during the 3-year study period. There were no differences in FeNO, FEV1, or FOT parameters at baseline between patients with and without exacerbations. The FeNO decreased significantly over 3 years in all patients regardless of exacerbation status. The FEV1 levels decreased gradually, whereas the percent predicted FEV1 levels significantly increased. We also observed significant improvement in FOT parameters; specifically reactance at 5 Hz (R5), resonant frequency (Fres), and integral of reactance up to the resonant frequency (AX). The stable group (without exacerbations) demonstrated significant relationships between the change in FeNO and the change in FEV1 and between the change in FEV1 and the change in FOT parameters. No significant correlations emerged in the exacerbation group. Conclusion: The decrease in FeNO and increase in the percent predicted FEV1 we observed in all study participants suggest that the coordinated care system model benefits patients with bronchial asthma. Although predicting which patients will experience an exacerbation at baseline may be difficult, monitoring changes in FeNO and FEV1 is useful in managing adults with stable asthma. Furthermore, monitoring changes in R5, Fres, and AX via forced oscillation technique testing is useful for detecting airflow limitation.