Table. 3—

Rotated factor loadings for traditional# measures

VariableTraditional factor 1Traditional factor 2
FEV1 0.155 0.932
FVC 0.051 0.924
Mean morning PEF−0.032 0.842
Daytime salbutamol use (reversed+) 0.768 0.001
Per cent nights no waking 0.701−0.047
Night-time symptom score (reversed) 0.820−0.046
Daytime symptom score (reversed) 0.792−0.093
Night-time salbutamol use (reversed) 0.795 0.129
Per cent salbutamol-free 24 h 0.767−0.160
  • Table shows the rotated factor loading between each individual variable and the factors derived from principal component analysis. FEV1: forced expiratory volume in one second; FVC: forced vital capacity; PEF: peak expiratory flow. #: FEV1/FVC, log provocative dose of methacholine causing a 20% fall in FEV1, FEV1 % predicted, PEF % best, PEF % predicted and symptom-free days contributed little and were omitted from the final factor analysis for traditional variables; : Significant loadings, indicating the variables that clustered together, i.e. were strongly correlated with each other; +: values were reversed for parameters for which a higher raw score indicated worse asthma control.