TABLE 2

RV/TLC ratio as predicted from multiple regression analysis of the total dataset

MalesFemales
95% CI95% CI
CoefficientLower limitUpper limitp-valueCoefficientLower limitUpper limitp-value
FEV1 % pred−0.002280−0.002438−0.002122<0.001−0.002280−0.002494−0.002066<0.001
FVC % pred−0.002443−0.002596−0.002290<0.001−0.002433−0.002634−0.002231<0.001
Age years0.0023160.0020880.002545<0.0010.0029970.0027170.003277<0.001
Height cm−0.001607−0.001882−0.001333<0.001−0.000944−0.001297−0.000590<0.001
BMI kg·m−2−0.001989−0.002381−0.001598<0.001−0.001399−0.001812−0.000986<0.001
Constant term1.0285110.9735831.083439<0.0010.8822960.8165850.948006<0.001

Regression coefficients and 95% CI are obtained from the mixed model, including visits 1–5. The predicted value of RV/TLC can be calculated as follows: C1×FEV1 % pred+C2×FVC % pred+C3×age+C4×height+C5×BMI+constant term. RV: residual volume; TLC: total lung capacity; FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; BMI: body mass index.