Impacts of Different Spirometry Reference Equations and Diagnostic Criteria on the Frequency of Airway Obstruction in Adult People of North China

Figures & data

Table 1 Participants’ Spirometric and Anthropometric Characteristics

	Total	Age 18–44	Age 45–59	Age 60–80
Subjects, n	57,888	12,134	19,977	25,777
Age, years	55.50±13.72	34.65±7.20	52.75±4.37	67.45±5.50
Sex (male, %)	58.18	48.82	56.01	64.26
Height, cm	163.37±8.17	165.17±8.38	163.52±7.97	162.41±8.07
Weight, kg	65.90±12.29	66.65±13.95	66.92±11.76	64.76±11.75
BMI, kg/m^2	24.64±3.93	24.33±4.18	24.98±3.75	24.52±3.92
FEV1, L	2.36±0.87	2.98±0.84	2.44±0.81	2.00±0.73
FVC, L	3.14±0.94	3.74±0.95	3.26±0.88	2.78±0.80
VC, L	3.26±0.93	3.82±0.94	3.37±0.88	2.92±0.80
FEV1/FVC	0.7397±0.1354	0.7959±0.1086	0.7415±0.1312	0.7181±0.1414

Note: Data are presented as mean ± standard deviation and n or n (%)

Abbreviations: BMI, Body Mass Index; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; VC, vital capacity.

Figure 1 Flowchart of the selection of the study population.

Table 2 The Comparison Between Zhongshan-2011 and GLI-2012 Reference Values

	Zhongshan-2011	GLI-2012	P-value
FEV1 pred, L	2.85±0.58	2.84±0.59	<0.001
Males	3.19±0.41	3.13±0.52	<0.001
Females	2.36±0.41	2.45±0.43	<0.001
FVC pred, L	3.40±0.70	3.55±0.71	<0.001
Males	3.85±0.45	3.94±0.58	<0.001
Females	2.76±0.44	3.00±0.46	<0.001
FEV1/FVC pred	0.8177±0.0253	0.8020±0.0253	<0.001
Males	0.8112±0.0233	0.7927±0.0225	<0.001
Females	0.8269±0.0250	0.8140±0.0231	<0.001
FEV1 LLN, L	2.31±0.53	2.32±0.58	<0.001
Males	2.59±0.41	2.63±0.49	<0.001
Females	1.91±0.40	1.80±0.39	<0.001
FVC LLN, L	2.80±0.62	2.97±0.68	<0.001
Males	3.21±0.39	3.37±0.54	<0.001
Females	2.24±0.39	2.42±0.43	<0.001
FEV1/FVC LLN	0.7465±0.0207	0.7038±0.0312	<0.001
Males	0.7394±0.0189	0.6965±0.0305	<0.001
Females	0.7565±0.0188	0.7141±0.0291	<0.001

Notes: The data was the predicted value and LLN of the participants. Data are presented as mean ± standard deviation. Zhongshan-2011, the reference value published by Zhongshan hospital 2011.

Abbreviations: FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GLI-2012, Global Lung Function Initiative 2012 equations; LLN, lower limits of normal; VC, vital capacity.

Figure 2 Bland-Altman spot of LLN and predicted values of GLI-2012 and Zhongshan-2011.

Abbreviations: Δ, difference of GLI-2012 data minus Zhongshan-2011 data; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GLI-2012, Global Lung Function Initiative 2012 equations; LLN, lower limits of normal.

Note: Zhongshan-2011, the reference value published by Zhongshan hospital 2011.Panels A, C and E illustrate the comparisons of LLN of FEV1, FVC and FEV1/FVC between GLI-2012 and Zhongshan-2011; Panels B, D and F illustrate the comparisons of predicted values of FEV1, FVC and FEV1/FVC between GLI-2012 and Zhongshan-2011. 

Table 3 The Influence of Diagnostic Criteria and Reference Equations on the Frequency of Airway Obstruction

Subjects, n(%)	All	Zhongshan-2011		P	GLI-2012		P
		FEV1/FVC<LLN	FEV1/FVC<92% pred		FEV1/FVC<LLN	FEV1/FVC<92% pred
All	57,888	22,715(39.24%)	23,874(41.24%)	<0.001	16,345(28.24%)	21,076(36.41%)	<0.001
Age 18–44	12,134	3842(31.66%)	3954(32.59%)	0.124	2853(23.51%)	3685(30.37%)	<0.001
Age 45–59	19,977	7761(38.85%)	8088(40.49%)	<0.001	5644(28.25%)	7067(35.38%)	<0.001
Age 60–80	25,777	11,112(43.11%)	11,832(45.90%)	<0.001	7848(30.45%)	10,324(40.05%)	<0.001

Notes: Data are presented as n or n (%). Zhongshan-2011, the reference value published by Zhongshan hospital in 2011.

Abbreviations: FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GLI-2012, Global Lung Function Initiative 2012 equations; LLN, lower limits of normal.

Table 4 Numbers of Concordant and Discordant Pairs When Using FEV1/FVC<LLN as Diagnostic Criterion Between GLI-2012 and Zhongshan-2011 to Diagnose Airway Obstruction

Subjects, n(%)	GLI-2012		Total
	No	Yes
All
Zhongshan-2011
No	35,172 (60.76%)	1 (0.00%)	35,173
Yes	6371 (11.01%)	16,344 (28.23%)	22,715
Total	41,543	16,345	57,888
Age 18–44
Zhongshan-2011
No	8291 (68.33%)	1 (0.01%)	8292
Yes	990 (8.16%)	2852 (23.50%)	3842
Total	9281	2853	12,134
Age 45–59
Zhongshan-2011
No	12,216 (61.15%)	0 (0.00%)	12,216
Yes	2117 (10.60%)	5644 (28.25%)	7761
Total	14,333	5644	19,977
Age 60–80
Zhongshan-2011
No	14,665 (56.89%)	0 (0.00%)	14,665
Yes	3264 (12.66%)	7848 (30.45%)	11,112
Total	17,929	7848	25,777

Note: Data are presented as n or n (%).

Abbreviations: FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GLI-2012, Global Lung Function Initiative 2012 equations; LLN, lower limits of normal.

Table 5 Numbers of Concordant and Discordant Pairs When Using FEV1/FVC<92% Pred as Diagnostic Criterion Between GLI-2012 and Zhongshan-2011 to Diagnose Airway Obstruction

Subjects, n(%)	GLI2-012		Total
	No	Yes
All
Zhongshan-2011
No	33,734 (58.27%)	280 (0.04%)	34,014
Yes	3078 (5.32%)	20,796 (35.92%)	23,874
Total	36,812	21,076	57,888
Age 18–44
Zhongshan-2011
No	8035 (66.22%)	145 (1.19%)	8180
Yes	414 (3.41%)	3540 (29.17%)	3954
Total	8449	3685	12,134
Age 45–59
Zhongshan-2011
No	11,810 (59.12%)	79 (0.39%)	11,889
Yes	1100 (5.51%)	6988 (34.98%)	8088
Total	12,910	7067	19,977
Age 60–80
Zhongshan-2011
No	13,889 (53.88%)	56 (0.22%)	13,945
Yes	1564 (6.07%)	10,268 (39.83%)	11,832
Total	15,453	10,324	25,777

Note: Data are presented as n or n (%).

Abbreviations: FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GLI-2012, Global Lung Function Initiative 2012 equations.