TABLE 4

Group comparisons for the relationship between multiple-breath washout test outcomes with inflammation and structural lung disease in children with cystic fibrosis when results from the first two trials of children who could perform three or more acceptable trials^# were compared with children who could perform two or more acceptable trials^¶

	Lung clearance index		First moment ratio		Second moment ratio
	Three or more acceptable trials	Two or more acceptable trials	Three or more acceptable trials	Two or more acceptable trials	Three or more acceptable trials	Two or more acceptable trials
Pulmonary inflammation
Total cell counts	0.40 (−0.01–0.80)	0.66 (0.34–0.98)***	0.08 (−0.01–0.17)	0.13 (0.06–0.20)***	0.65 (−0.11–1.41)	1.08 (0.49–1.68)***
Neutrophil cells	0.40 (0.14–0.66)*	0.44 (0.21–0.67)***	0.07 (0.01–0.13)*	0.08 (0.03–0.13)**	0.58 (0.06–1.10)*	0.72 (0.30–1.14)**
Neutrophil elastase concentration	0.29 (0.04–0.54)*	0.29 (0.10–0.48)***	0.07 (0.01–0.12)*	0.06 (0.02–0.10)**	0.56 (0.08–1.03)*	0.53 (0.19–0.86)**
Interleukin-8 concentration	0.32 (0.09–0.55)*	0.25 (0.08–0.42)**	0.06 (0.01–0.11)*	0.05 (0.01–0.08)**	0.48 (0.04–0.93)*	0.40 (0.10–0.71)**
Structural lung disease
%Dis	0.07 (−0.08–0.22)	0.09 (−0.01–0.19)	0.02 (−0.02–0.05)	0.02 (−0.01–0.04)	0.12 (−0.17–0.41)	0.14 (−0.05–0.33)
%Bx	0.06 (−0.10–0.22)	0.07 (−0.06–0.20)	0.01 (−0.02–0.05)	0.01 (−0.01–0.04)	0.08 (−0.23–0.40)	0.10 (−0.13–0.34)
%TA	0.04 (−0.01–0.09)	0.03 (−0.01–0.07)	0.01 (−0.01–0.02)	0.01 (−0.01–0.01)	0.06 (−0.03–0.16)	0.05 (−0.01–0.12)

The coefficient for the linear mixed effects model (adjusted for test centre) is 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. ^#: n=49; ^¶: n=71. *: p<0.05; **: p<0.01; ***: p<0.001.