Figure 4. Outcomes of True Filtration vs Sham Filtration, Stratified by Baseline Eosinophilic Airway Inflammation, as Indicated by Baseline Fractional Exhaled Nitric Oxide (FeNO) or Blood Eosinophil Count.
The FeNO cut point was 35 ppb. The blood eosinophil count cut point was 450 cells per μL (to convert to cells × 109, multiply by 0.001). For all outcomes except peak expiratory flow (PEF), the points and bars show mean and 95% CIs for outcome improvements when comparing the before-and-after filtration changes in outcome levels between true filtration and sham filtration. For PEF, the point and the bar show the means and 95% CIs when comparing PEF values measured during the true filtration period with PEF values measured during the sham filtration period. For all outcomes, positive values indicate improvements and negative values indicate deterioration. For FeNO data, the analysis was performed on log-transformed FeNO data, and the result was converted back to untransformed data for presentation in this figure. FEF25-75 indicates forced expiratory flow during 25% to 75% of forced vital capacity; FEV1, forced expiratory volume during the first second; Fres, resonant frequency; FVC, forced vital capacity; PEF, peak expiratory flow; R5, airway resistance measured at 5 Hz; R20, airway resistance measured at 20 Hz; R5-R20, the difference between R5 and R20, reflecting small airway resistance; X5, airway reactance measured at 5 Hz.