Sample size n | Regression coefficient | 95% confidence interval | p-value | |
FEV1 z-score# | 161 | 0.151 | 0.05–0.25 | 0.002 |
FEV1/FVC | 162 | 1.113 | −0.23–2.46 | 0.104 |
Age of onset years | 247 | 0.028 | −0.03–0.08 | 0.311 |
Specific airway conductance kPa·s−1 | 78 | 0.132 | −0.16–0.42 | 0.366 |
Log exacerbations in previous year | 263 | −0.523 | −0.67– −0.38 | <0.001 |
ACT combined z-score | 196 | 0.730 | 0.63–0.83 | <0.001 |
BMI kg·m−2 | 261 | −0.036 | −0.06– −0.01 | 0.011 |
MARS total | 249 | −0.040 | −0.09–0.01 | 0.097 |
Hay fever diagnosed | 211 | −0.281 | −0.57–0.01 | 0.057 |
Eczema diagnosed | 225 | −0.116 | −0.42–0.19 | 0.452 |
Atopy | 225 | −0.070 | −0.34–0.2 | 0.612 |
Second-hand smoke | 257 | −0.022 | −0.33–0.29 | 0.890 |
White ethnicity | 263 | 0.346 | 0.04–0.66 | 0.028 |
Data represent linear regression analyses looking at the association between each factor and quality of life. Quality of life was assessed by the Paediatric Asthma Quality of Life Questionnaire (PAQLQ) or the Paediatric Asthma Caregiver's Quality of Life Questionnaire (PACQLQ). To allow the joint analysis of the PAQLQ and PACQLQ, data were transformed to improve symmetry and then z-scores were calculated. In order to make maximum use of the data, plethysmography (specific airway conductance), with 194 missing values, was excluded from joint modelling. Analysis was also performed for PAQLQ and PACQLQ separately (results in the online supplementary material). FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; ACT: Asthma Control Test; BMI: body mass index; MARS: Medication Adherence Report Scale. #: predictive lung function equations from Quanjer et al. [19] were used to generate z-scores.