TABLE 2

Analysis of association between covariates and repeated measurements of forced expiratory volume in 1 s % predicted, from multilevel models

Covariate	B coefficient (95% CI)^#	p-value	p-value from likelihood ratio test for interaction with age^¶	Patients included in analysis⁺
Sex	4.02 (−4.02–12.05)	0.33		108
BMI	0.31 (−0.17–0.79)	0.21		108
Age at diagnosis	0.001 (−0.35–0.35)	1.00		59
Nasal nitric oxide	0.10 (−0.01–0.22)	0.09		68
Ciliary beat frequency	6.47 (−15.76–2.82)	0.17		101
*Pseudomonas aeruginosa*	−0.37 (−2.37–1.63)	0.72		107
Ciliary ultrastructure by TEM		0.03^§	0.04	97
Normal or inconclusive	0.00
Outer±inner arm defect	3.90 (−7.01–14.80)
Microtubular defects	10.29 (−23.59–3.01)
Extent of bronchiectasis	−0.18 (−0.41–0.05)^ƒ	0.122	0.03	68
Severity of bronchial wall dilatation	−0.17 (−0.36–0.02)^ƒ	0.08	0.01⁺	68
Bronchial wall thickness	−0.29 (−0.56– −0.01)^ƒ	0.045	0.06⁺	68
Small airway plugging (continuous)	−0.29 (−0.46– −0.13)^ƒ	<0.001	0.196⁺	68
Large airway plugging	−0.63 (−1.08– −0.17)^ƒ	0.007	0.19⁺	68
Mosaicism	−0.26 (−0.46– −0.07)^ƒ	0.008	0.16⁺	68

BMI: body mass index; TEM: transmission electron microscopy. ^#: B coefficients are to be interpreted as the change in forced expiratory volume in 1 s (FEV₁) for each unit change of the covariate after adjusting for age at which the measurement was made; ^¶: tests for interaction with age assess whether these covariates affect how FEV₁ changes as patients get older; ⁺: patients included in each of these regression analyses had non-missing data for FEV₁, age at the time the FEV₁ measure was taken, the covariate under study, and ciliary ultrastructure where this was adjusted for; ^§: the p-value for this covariate relates to the covariate as a whole rather than one level or another; ^ƒ: after additionally adjusting for ciliary ultrastructure.