Table 2

Coefficients from prediction equations for normal lung function measures by sex

 b 0 b 1 b 2 b 3 Corresponding variable Intercept A A2 ln H ln FEV1 L Males (R2=0.59; σ=0.14) Mean Age ≤25 yrs −10.41186 0.09569 −0.00221 2.10839 Age >25 yrs −9.37674 0.00183 −0.00011 2.10839 LLN Age ≤25 yrs −10.75820 0.10320 −0.00231 2.10839 Age >25 yrs −9.72308 0.00933 −0.00021 2.10839 Females (R2=0.69; σ=0.14) Mean −8.49717 0.00422 −0.00015 1.90019 LLN −8.68467 0.00495 −0.00018 1.90019 ln FVC L Males (R2=0.52; σ=0.14) Mean Age ≤25 yrs −11.45146 0.09895 −0.00216 2.32222 Age >25 yrs −10.36706 0.00434 −0.00011 2.32222 LLN Age ≤25 yrs −11.63230 0.09795 −0.00217 2.32222 Age >25 yrs −10.54790 0.00334 −0.00012 2.32222 Females (R2=0.62; σ=0.15) Mean −9.66999 0.00837 −0.00017 2.14118 LLN −9.84941 0.00772 −0.00018 2.14118 ln FEV1/FVC Males (R2=0.15; σ=0.08) Mean 1.03981 −0.00394 0.00002 −0.21653 LLN 0.82621 0.00101 −0.00005 −0.21653 Females (R2=0.16; σ=0.08) Mean 1.15822 −0.00415 0.00002 −0.23815 LLN 1.00699 −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