Prediction equations for normal and low lung function from the Health Survey for England

E. Falaschetti; J. Laiho; P. Primatesta; S. Purdon

doi:10.1183/09031936.04.00055204

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Fig. 1.—
Age dependency of forced expiratory volume in one second (FEV₁) (a, c) and forced vital capacity (FVC) distribution (b, d) in males (a, b) and females (c, d). Each subject is represented by a dot (–––: smoothed values (lowess)).
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Fig. 2.—
Predicted mean (––––) and fifth percentile (═) for forced expiratory volume in one second (FEV₁) (a, d), forced vital capacity (FVC) (b, e) and FEV₁/FVC (c, f) in males (height 175 cm) (a–c) and females (height 165 cm) (d–f) by age.
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Fig. 3.—
Observed (▪) and predicted (•) mean forced vital capacity (FVC) in present study and European Coal and Steel Community reference values (▴) by age in a) males and b) females.
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Fig. 4.—
Comparison of mean predicted forced expiratory volume in one second (FEV₁) (a, c) and forced vital capacity (FVC) (b, d) by age in males (a, b) and females (c, d) in present study (▵) and studies of BrÄndli et al. 1 (▪), Langhammer et al. 13 (♦) and Hankinson et al. 14 (○).
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Fig. 5.—
Comparison of mean predicted forced expiratory volume in one second (FEV₁)/forced vital capacity (FVC) by age in a) males and b) females in the present study (▴) and studies of BrÄndli et al. 1 (▪), Langhammer et al. 13 (♦), Hankinson et al. 14 (•) and European Coal and Steel Community 4 (▾).

Tables

Figures

Table 1

Reference sample selection criteria and characteristics of the study sample

	Males	Females
Participants (White) interviewed n
Total	13883	16646
Less invalid spirometry data	11854	13554
Less ever smokers	4643	6845
Less nonhealthy subjects	3107	4195
Less irreproducible data	2497	3556
Age in years n
16–24	424	507
25–34	620	802
35–44	583	750
45–54	376	593
55–64	260	416
65–74	157	329
75–84	51	134
≥85	8	25
Age last birthday yrs	40±15.7	43±17.0
Height cm	176±6.8	162±6.4
FEV₁ L	4.1±0.81	2.9±0.65
FVC L	5.0±0.94	3.5±0.74
FEV₁/FVC	0.82±0.072	0.83±0.071

Data are presented as absolute values or mean±sem
FEV₁: forced expiratory volume in one second
FVC: forced vital capacity

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=e^b^{0+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

Table 3

Percentage of population with lung function below the lower limit of normal in “healthy” population for the Health Survey for England reference curves using different estimates of the 5^th percentile by sex and age group

Age yrs	Present model^#		Mean – 1.645σ
Age yrs	FEV₁	FVC	FEV₁	FVC
Males
16–24	4.0	5.0	4.5	4.0
25–34	5.8	5.0	5.0	3.9
35–44	6.3	6.0	5.3	6.3
45–54	3.5	5.1	4.3	6.6
55–64	3.1	3.8	6.9	6.9
65–74	6.4	6.4	12.1	10.8
≥75	5.1	5.1	8.5	15.3
All	5.0	5.2	5.6	5.9
Females
16–24	5.5	6.1	3.0	3.7
25–34	4.6	5.7	3.2	3.2
35–44	6.3	4.4	4.9	4.1
45–54	5.1	5.4	5.6	5.9
55–64	5.3	6.7	6.5	7.9
65–74	5.5	5.2	10.9	9.1
≥75	5.7	3.8	13.8	10.7
All	5.4	5.4	5.5	5.4

σ: sd of residuals
FEV₁: forced expiratory volume in one second
FVC: forced vital capacity
^#: lower limit of normal=e^b^{0+b1A+b2A2+b3ln H}
coefficient values given in table 2⇑

Table 4

Percentage of population defined as exhibiting lung function below the lower limit of normal (LLN) in “healthy” and whole populations using the Health Survey for England (HSE) and European Coal and Steel Community (ECSC) reference curves by sex and age group^#

Age yrs	HSE^¶				ECSC⁺
	Healthy		Whole		Healthy		Whole
	FEV₁	FVC	FEV₁	FVC	FEV₁	FVC	FEV₁	FVC
Males
18–24	4.9	4.6	7.4	7.7	4.3	3.0	5.8	5.1
25–34	5.8	5.0	8.8	7.4	3.1	2.6	5.5	4.5
35–44	6.3	6.0	12.5	8.8	2.6	2.6	6.3	4.5
45–54	3.5	5.1	15.1	10.2	0.5	1.6	8.3	5.4
55–64	3.1	3.8	17.7	12.7	1.2	1.5	12.0	8.9
65–70	7.5	7.5	22.8	17.1	5.7	3.8	18.1	13.0
All	5.2	5.2	13.4	10.0	2.6	2.4	8.4	6.2
Females
18–24	4.7	5.8	9.7	7.8	1.7	3.3	5.1	4.9
25–34	4.6	5.7	9.1	7.2	2.4	1.9	4.3	3.4
35–44	6.3	4.4	12.5	9.5	1.9	0.9	5.1	3.4
45–54	5.1	5.4	13.8	10.1	1.7	0.7	5.3	2.8
55–64	5.3	6.7	17.5	13.9	1.7	1.2	8.9	4.8
65–70	4.8	5.3	17.8	13.8	1.0	1.0	9.6	5.5
All	5.2	5.5	12.9	9.9	1.9	1.4	5.9	3.9

^#: range restricted to 18–70 yrs, as recommended for the ECSC prediction equations, to permit comparison
FEV₁: forced expiratory volume in one second
FVC: forced vital capacity
^¶: LLN computed from mean lung function=e^b^{0+b1A+b2A2+b3ln H}
coefficient values given in table 2⇑
⁺: LLN computed from mean – 1.645σ

Table 5

Mean differences and mean differences squared between values observed in the present study and predicted by various prediction equations

First author [ref.]	Age yrs	Males				Females
First author [ref.]	Age yrs	Subjects n	Mean DIFF	Mean DIFF %	Mean squared DIFF	Subjects n	Mean DIFF	Mean DIFF %	Mean squared DIFF
FEV₁
Present study	16–94	2479	0.04	0.86	0.28	3556	0.03	0.87	0.14
BrÄndli 1	18–60	2056	0.00	0.04	0.29	2755	−0.01	−0.33	0.15
Langhammer 13	20–80	2249	−0.06	−1.56	0.29	3249	−0.06	−2.09	0.15
Hankinson 14	16–80	2459	0.07	1.64	0.29	3489	0.02	0.69	0.15
ECSC 4	18–70	2250	0.25	6.01	0.35	3129	0.20	6.77	0.19
FVC
Present study	16–94	2479	0.04	0.88	0.44	3556	0.03	0.97	0.23
BrÄndli 1	18–60	2056	−0.14	−2.77	0.48	2755	−0.11	−3.00	0.26
Langhammer 13	20–80	2249	−0.05	−0.92	0.46	3249	−0.07	−2.06	0.24
Hankinson 14	16–80	2459	−0.04	−0.81	0.45	3489	−0.04	−1.09	0.24
ECSC 4	18–70	2250	0.34	6.62	0.57	3129	0.35	9.73	0.37
FEV₁/FVC
Present study	16–94	2479	0.0016	0.19	0.0043	3556	0.0048	0.57	0.0042
Brändli 1	18–60	2056	0.0225	2.73	0.0045	2755	0.0210	2.51	0.0044
Langhammer 13	20–80	2249	−0.0026	−0.32	0.0045	3249	0.0056	0.68	0.0044
Hankinson 14	16–80	2459	0.0223	2.72	0.0048	3489	0.0156	1.87	0.0045
ECSC 4	18–70	2250	0.0199	2.43	0.0046	3129	0.0229	2.74	0.0046

FEV₁: forced expiratory volume in one second
FVC: forced vital capacity
ECSC: European Coal and Steel Community
DIFF: difference