Table 3

Multiple linear regression predictive equations for lung function outcomes FVC, FEV₁, PEF, and FEF_75–25*

Variable	β	95% CI for β	p value
*Ethnic origin automatically included in the model. Other terms retained if p<0.05 (smoking p<0.10) or higher order term in covariate included.
Predictive equation for outcome FVC (l)
Constant	2.218	(−1.487 to 5.924)	0.24
Gender (additive effect of being female compared to male)	−0.075	(−0.127 to −0.024)	0.004
Ethnic origin (additive effect of being Asian compared to white)	−0.226	(−0.280 to −0.172)	<0.001
Standing height (m)	−3.337	(−8.872 to 2.198)	0.24
Standing height² (m²)	2.250	(0.182 to 4.318)	0.033
Chest volume calculated as a box (l)	0.053	(0.032 to 0.074)	<0.001
	n = 247; adjusted R² = 0.78

Predictive equation for outcome FEV₁ (l)
Constant	3.346	(−0.208 to 6.899)	0.065
Ethnic origin (additive effect of being Asian compared to white)	−0.179	(−0.231 to −0.128)	<0.001
Standing height (m)	−4.966	(−10.274 to 0.343)	0.067
Standing height² (m²)	2.769	(0.785 to 4.753)	0.006
Chest volume calculated as a box (l)	0.031	(0.011 to 0.500)	0.002
	n = 247; adjusted R² = 0.72

Predictive equation for outcome PEF (l/s)
Constant	−3.746	(−4.879 to −2.613)	<0.001
Ethnic origin (additive effect of being Asian compared to white)	−0.170	(−0.344 to 0.003)	0.055
Standing height (m)	4.835	(3.602 to 6.068)	<0.001
Chest height (cm)	0.0565	(0.006 to 0.107)	0.028
	n = 251; adjusted R² = 0.45

Predictive equation for outcome FEF_75–25 (l/s)
Constant	−1.797	(−2.641 to −0.952)	<0.001
Ethnic origin (additive effect of being Asian compared to white)	−0.195	(−0.344 to −0.046)	0.011
Standing height (m)	3.026	(2.414 to 3.637)	<0.001
Asthma	−0.228	(−0.415 to −0.041)	0.017
Mother smokes 1–10 cigarettes per day	−0.105	(−0.405 to 0.195)	0.49
Mother smokes 11+ cigarettes per day	−0.315	(−0.562 to −0.068)	0.013
	n = 263; adjusted R² = 0.30