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

CovariateB coefficient
(95% CI)#
p-valuep-value from likelihood ratio test for interaction with agePatients included in analysis+
Sex4.02 (−4.02–12.05)0.33108
BMI0.31 (−0.17–0.79)0.21108
Age at diagnosis0.001 (−0.35–0.35)1.0059
Nasal nitric oxide0.10 (−0.01–0.22)0.0968
Ciliary beat frequency6.47 (−15.76–2.82)0.17101
Pseudomonas aeruginosa−0.37 (−2.37–1.63)0.72107
Ciliary ultrastructure by TEM0.03§0.0497
 Normal or inconclusive0.00
 Outer±inner arm defect3.90 (−7.01–14.80)
 Microtubular defects10.29 (−23.59–3.01)
Extent of bronchiectasis−0.18 (−0.41–0.05)ƒ0.1220.0368
Severity of bronchial wall dilatation−0.17 (−0.36–0.02)ƒ0.080.01+68
Bronchial wall thickness−0.29 (−0.56– −0.01)ƒ0.0450.06+68
Small airway plugging (continuous)−0.29 (−0.46– −0.13)ƒ<0.0010.196+68
Large airway plugging−0.63 (−1.08– −0.17)ƒ0.0070.19+68
Mosaicism−0.26 (−0.46– −0.07)ƒ0.0080.16+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.