Males | Females | |||||
Parameter | Equation | R^{2} | RSD | Equation | R^{2} | RSD |
FVC | Exp (−12.396+2.733 ln(H)−0.0000592 A^{2}) | 0.63 | 0.12 | Exp (−9.851+2.189 ln(H)−0.000143A^{2}+0.006439A | 0.68 | 0.13 |
FEV_{1} | Exp (−10.556+2.342 ln(H)−0.0000685 A^{2}) | 0.60 | 0.12 | Exp (−9.091+2.004 ln(H)−0.000163 A^{2}+0.007237A | 0.72 | 0.13 |
FEV_{1}/FVC | Exp (6.433−0.385 ln(H)−0.000923A) | 0.05 | 0.07 | Exp (5.403−0.185ln(H)−0.00115A) | 0.06 | 0.07 |
PEF L·s^{−1} | Exp (−6.632+1.731 ln(H)−0.000436A^{2}) | 0.16 | 0.23 | Exp (−7.726+1.808 ln(H)−0.000286A^{2}+0.022A) | 0.34 | 0.25 |
FEF_{25%–75%} L·s^{−1} | Exp (−3.764+1.037 ln(H)−0.000102A^{2}) | 0.26 | 0.27 | Exp (−6.442+1.474 ln(H)−0.000243A^{2}+0.01199A) | 0.41 | 0.30 |
Log AUC L× L·s^{−1} | Exp (−156.16+37.12ln(H)−0.184H−0.00012A^{2}) | 0.51 | 0.27 | Exp (−16.597+3.698 ln(H)−0.00041A^{2}+0.02408A) | 0.65 | 0.29 |
A: age in yrs
H: height in cm
Exp (x): e^{x}
FVC: forced vital capacity
FEV_{1}: forced expiratory volume in one second
PEF: peak expiratory flow
FEF_{25%–75%}: forced mid-expiratory flow
AUC: area under curve
The predicted value for FEV_{1} in a 20 yrs-old man with height 180 cm is computed as: FEV_{1}= e^{(−10.556 + 2.342×ln(180) – 0.0000685×400)} = e^{1.5785} =4.848
The lower limit of normal (LLN) is computed as: LLN FEV_{1} = e^{(predicted−1.645×RSD)} = e^{1.3811} = 3.979