TABLE 4.

Reference equations for men and women between 20 and 90 years of age for predicting normal FEV₁, FVC and FEV₁/FVC ratio (n=1656)

Sex	Parameter	Intercept	Age	Height	R2	SD of difference (SEE)*	Observations, n
Male	FEV1	−2.06961	−0.03167	0.04215	0.56010	0.50586	722
	FVC	−5.39383	−0.02286	0.06500	0.45720	0.63557	708
	FEV1/FVC	122.0893	−0.27977	−0.17794	0.35770	5.48656	703
Female	FEV1	−1.68697	−0.02773	0.03557	0.68390	0.36973	926
	FVC	−4.11886	−0.02124	0.05310	0.52160	0.49381	917
	FEV1/FVC	120.59691	−0.30805	−0.16531	0.39550	5.68808	916

Men: FEV₁ = 0.04215 × height (cm) – 0.03167A – 2.06961; FVC = 0.06500 × height (cm) – 0.02286A – 5.39383; FEV₁/FVC = −0.17794 × height (cm) −0.27977A + 122.0893; Women: FEV₁ = 0.03557 × height (cm) – 0.02773A – 1.68697; FVC = 0.05310 × height (cm) – 0.02124A – 4.11886; FEV₁/FVC = – 0.16531 × height (cm) – 0.30805A + 120.59691.

^*The 5th percentile lower limit of normal (LLN) of the population can be computed for these lung function parameters using the following formula: LLN = predicted value – (1.645 × SEE). FEV₁ Forced expiratory volume in 1 s; FVC Forced vital capacity; SEE Standard error of the estimate