TABLE 3

Relationship between multiple-breath washout (MBW) test outcomes with inflammation and structural lung disease in children with cystic fibrosis when MBW outcomes were calculated from all trials obtained compared with the first two trials obtained in visits with three or more acceptable trials

Lung clearance indexFirst moment ratioSecond moment ratio
All trialsFirst two trialsAll trialsFirst two trialsAll trialsFirst two trials
MBW outcomes8.19±1.508.19±1.461.81±0.311.80±0.307.11±2.837.04±2.84
Pulmonary inflammation
 Total cell count0.35 (−0.04–0.75)0.40 (−0.01–0.80)0.06 (−0.02–0.14)0.08 (−0.01–0.17)0.50 (−0.21–1.22)0.65 (−0.11–1.41)
 Neutrophil cells0.38 (0.12–0.63)*0.40 (0.14–0.66)*0.07 (0.01–0.12)*0.07 (0.01–0.13)*0.55 (0.07–1.03)*0.58 (0.06–1.10)*
 Neutrophil elastase concentration0.28 (0.04–0.53)*0.29 (0.04–0.54)*0.06 (0.01–0.11)*0.07 (0.01–0.12)*0.49 (0.05–0.93)*0.56 (0.08–1.03)*
 Interleukin-8 concentration0.31 (0.08–0.53)*0.32 (0.09–0.55)*0.05 (0.01–0.10)*0.06 (0.01–0.11)*0.45 (0.04–0.87)*0.48 (0.04–0.93)*
Structural lung disease
 %Dis0.08 (−0.06–0.23)0.07 (−0.08–0.22)0.02 (−0.01–0.05)0.02 (−0.02–0.05)0.13 (−0.14–0.39)0.12 (−0.17–0.41)
 %Bx0.07 (−0.09–0.23)0.06 (−0.10–0.22)0.01 (−0.02–0.04)0.01 (−0.02–0.05)0.10 (−0.19–0.39)0.08 (−0.23–0.40)
 %TA0.03 (−0.02–0.08)0.04 (−0.01–0.09)0.01 (−0.01–0.01)0.01 (−0.01–0.02)0.05 (−0.04–0.14)0.06 (−0.03–0.16)

The raw MBW outcomes are presented, and the coefficients for the linear mixed effects model (adjusted for test centre) for associations with markers of pulmonary inflammation and structural lung disease are presented with 95% confidence intervals. %Dis: volume proportion of the lung with airway disease; %Bx: volume proportion of the lung with bronchiectasis; %TA: volume proportion of the lung with trapped air. *: p<0.05.