Table 2

Coefficients from prediction equations for normal lung function measures by sex

b 0 b 1 b 2 b 3
Corresponding variableInterceptAA2ln H
ln FEV1 L
Males (R2=0.59; σ=0.14)
 Mean
  Age ≤25 yrs−10.411860.09569−0.002212.10839
  Age >25 yrs−9.376740.00183−0.000112.10839
 LLN
  Age ≤25 yrs−10.758200.10320−0.002312.10839
  Age >25 yrs−9.723080.00933−0.000212.10839
Females (R2=0.69; σ=0.14)
 Mean−8.497170.00422−0.000151.90019
 LLN−8.684670.00495−0.000181.90019
ln FVC L
Males (R2=0.52; σ=0.14)
 Mean
  Age ≤25 yrs−11.451460.09895−0.002162.32222
  Age >25 yrs−10.367060.00434−0.000112.32222
 LLN
  Age ≤25 yrs−11.632300.09795−0.002172.32222
  Age >25 yrs−10.547900.00334−0.000122.32222
Females (R2=0.62; σ=0.15)
 Mean−9.669990.00837−0.000172.14118
 LLN−9.849410.00772−0.000182.14118
ln FEV1/FVC
Males (R2=0.15; σ=0.08)
 Mean1.03981−0.003940.00002−0.21653
 LLN0.826210.00101−0.00005−0.21653
Females (R2=0.16; σ=0.08)
 Mean1.15822−0.004150.00002−0.23815
 LLN1.00699−0.00196−0.00001−0.23815

  • Model: mean lung function=eb0+b1A+b2A2+b3ln H

  • For example, a male aged 31 yrs with a height of 173 cm would have a predicted forced expiratory volume in one second (FEV1) of 4.53 L (from e−9.37674+(0.00183×31)−(0.00011×312)+2.10839ln173), and a predicted forced vital capacity (FVC) of 5.48 L (from e−10.36706+(0.00434×31)−(0.00011×312)+2.32222ln173)

  • R2: fraction of explained variance

  • σ: sd of residuals

  • LLN: lower limit of normal

  • A: age

  • H: height