The Relationship Between BMI and Lung Function in Populations with Different Characteristics: A Cross-Sectional Study Based on the Enjoying Breathing Program in China

Figures & data

Figure 1 Flow chart for participants included in the analysis of relationship between BMI and lung function.

Table 1 Characteristics of Participants Included in the Analysis of Relationship Between BMI and Lung Function

	Total	Not at Risk	At Risk	p value (at Risk vs Not at Risk)	Normal Spirometry	PRISm	Obstructive Spirometry	p value (PRISm vs Normal)	p value (Obstructive vs Normal)
Number (n)	32,033	16,166	15,867		18,828	6325	6880
Age (year, mean±SD)	58.75±12.04	52.35±11.29	65.27±8.87	<0.001	56.83±12.06	58.54±12.10	64.20±10.15	<0.001	<0.001
Sex				<0.001				<0.001	<0.001
Male (n, %)	17,802 (55.57%)	7510 (46.46%)	10,292 (64.86%)		9422 (50.04%)	3655 (57.79%)	4725 (68.68%)
Female (n, %)	14,231 (44.43%)	8656 (53.54%)	5575 (35.14%)		9406 (49.96%)	2670 (42.21%)	2155 (31.32%)
BMI (kg/m^2, mean±SD)	24.11±3.50	24.92±3.38	23.30±3.43	<0.001	24.38±3.37	24.41±3.56	23.12±3.62	0.495	<0.001
Smoker (n, %)	13,914 (43.44%)	4649 (28.76%)	9265 (58.39%)	<0.001	7263 (38.58%)	2774 (43.86%)	3877 (56.35%)	<0.001	<0.001
Symptom
Cough (n, %)	10,406 (32.49%)	2007 (12.41%)	8399 (52.93%)	<0.001	5233 (27.79%)	2033 (32.14%)	3140 (45.64)	<0.001	<0.001
Breathlessness (n, %)	15,926 (49.72%)	4622 (28.59%)	11,304 (71.24%)	<0.001	7979 (42.38%)	3272 (51.73%)	4675 (67.95%)	<0.001	<0.001
Biofuel exposure (n, %)	19,570 (61.09%)	9836 (60.84%)	9734 (61.35%)	0.355	11,646 (61.85%)	3927 (62.09%)	3997 (58.10%)	0.742	<0.001
Family history (n, %)	6384 (19.93%)	1817 (11.24%)	4567 (28.78%)	<0.001	3452 (18.33%)	1296 (20.49%)	1636 (23.78%)	<0.001	<0.001
COPD-SQ (score, mean±SD)	14.81±6.88	9.28±3.95	20.44±4.08	<0.001	13.22±6.29	14.66±6.59	19.30±6.69	<0.001	<0.001
Lung function
FEV1 (l, mean±SD)	2.25±0.82	2.49±0.77	2.00±0.80	<0.001	2.65±0.67	1.81±0.56	1.54±0.73	<0.001	<0.001
FVC (l, mean±SD)	2.93±2.07	3.13±0.95	2.72±2.77	<0.001	3.26±0.82	2.27±0.73	2.62±4.11	<0.001	<0.001
FEV1/FVC (mean±SD)	0.77±0.12	0.80±0.09	0.73±0.14	<0.001	0.81±0.06	0.81±0.10	0.59±0.09	0.003	<0.001

Abbreviations: BMI, body mass index; COPD-SQ, the COPD Screening Questionnaire; COPD, Chronic Obstructive Pulmonary Disease; PRISm preserved ratio impaired spirometry; FEV1, the predicted forced expiratory volume in one second; FVC, the Predicted forced vital capacity.

Table 2 The Relationship Between BMI and Lung Function According to COPD-SQ Scores

Participants	BMI	FEV1		FVC		FEV1/FVC
		Unadjusted	Adjusted	Unadjusted	Adjusted	Unadjusted	Adjusted
People not at risk of COPD	BMI<18.5	−0.10 (−0.25, 0.06)	−0.49 (−0.68, −0.29)	−0.01 (−0.13, 0.11)	−0.26 (−0.43, −0.09)	−2.36 (−3.50, −1.22)	−2.97 (−4.11, −1.84)
	18.5≤BMI<23.9	Ref	Ref	Ref	Ref	Ref	Ref
	24.0≤BMI<27.9	−0.06 (−0.10, −0.02)	0.04 (−0.02, 0.10)	−0.06 (−0.10, −0.03)	−0.04 (−0.09, 0.00)	0.30 (−0.07, 0.68)	1.22 (0.83, 1.61)
	28.0≤BMI<34.9	−0.15 (−0.21, −0.09)	−0.07 (−0.15, 0.00)	−0.14 (−0.19, −0.09)	−0.15 (−0.22, −0.09)	0.17 (−0.32, 0.67)	1.21 (0.70, 1.72)
	BMI≥35.0	−0.38 (−0.67, −0.10)	−0.42 (−0.76, −0.07)	−0.25 (−0.48, −0.01)	−0.29 (−0.59, 0.01)	−0.45 (−2.69, 1.79)	0.32 (−1.96, 2.60)
People at risk of COPD	BMI<18.5	−0.59 (−0.67, −0.51)	−0.63 (−0.73, −0.54)	−0.45 (−0.52, −0.38)	−0.51 (−0.59, −0.43)	−2.38 (−2.82, −1.95)	−2.47 (−2.94, −2.01)
	18.5≤BMI<23.9	Ref	Ref	Ref	Ref	Ref	Ref
	24.0≤BMI<27.9	0.13 (0.08, 0.17)	0.33 (0.27, 0.38)	0.00 (−0.01, 0.01)	0.01 (−0.01, 0.03)	1.34 (1.07, 1.62)	2.23 (1.93, 2.53)
	28.0≤BMI<34.9	0.04 (−0.04, 0.11)	0.31 (0.22, 0.39)	−0.09 (−0.15, −0.03)	0.01 (−0.02, 0.03)	1.69 (1.26, 2.13)	2.70 (2.24, 3.15)
	BMI≥35.0	−0.30 (−0.69, 0.09)	0.09 (−0.35, 0.53)	−0.39 (−0.72, −0.05)	−0.15 (−0.54, 0.24)	1.08 (−1.22, 3.38)	2.28 (−0.03, 4.59)

Notes: Adjusted model: sex, age, smoke, cough, breath shortness, biofuel use and family history.

Abbreviations: BMI, body mass index; COPD-SQ, the COPD Screening Questionnaire; COPD, Chronic Obstructive Pulmonary Disease; FEV1, the predicted forced expiratory volume in one second; FVC, the Predicted forced vital capacity.

Figure 2 The relationship between BMI and lung function according to COPD-SQ scores. (A) The relationship between BMI and lung function in people at risk of COPD. (B) The relationship between BMI and lung function in people not at risk of COPD.

Table 3 The Relationship Between BMI and Lung Function According to Lung Function Test

Participants	BMI	FEV1		FVC		FEV1/FVC
		Unadjusted	Adjusted	Unadjusted	Adjusted	Unadjusted	Adjusted
People with normal spirometry	BMI<18.5	−0.25 (−0.38, −0.12)	−0.24 (−0.44, −0.04)	−0.19 (−0.30, −0.08)	−0.17 (−0.33, 0.01)	−1.03 (−2.42, 0.37)	−1.79 (−2.18, 0.60)
	18.5≤BMI<23.9	Ref	Ref	Ref	Ref	Ref	Ref
	24.0≤BMI<27.9	0.06 (0.01, 0.10)	0.01 (−0.06, 0.08)	0.02 (−0.02, 0.06)	−0.05 (−0.11, 0.01)	1.04 (0.55, 1.52)	1.06 (0.56, 1.55)
	28.0≤BMI<34.9	−0.04 (−0.11, 0.03)	−0.22 (−0.33, −0.11)	−0.08 (−0.13, −0.02)	−0.26 (−0.34, −0.17)	1.40 (0.72, 2.08)	1.29 (0.59, 1.98)
	BMI≥35.0	−0.56 (−0.95, −0.18)	−0.97 (−1.60, −0.33)	−0.49 (−0.80, −0.18)	−0.76 (−1.25, −0.28)	1.67 (−1.71, 5.05)	1.22 (−2.32, 4.76)
People with PRISm	BMI<18.5	−0.50 (−0.73, −0.27)	−0.56 (−0.86, −0.26)	−0.33 (−0.50, −0.15)	−0.33 (−0.55, −0.11)	−0.12 (−1.49, 1.25)	−0.03 (−1.34, 1.28)
	18.5≤BMI<23.9	Ref	Ref	Ref	Ref	Ref	Ref
	24.0≤BMI<27.9	0.13 (0.03, 0.23)	0.22 (0.08, 0.36)	0.09 (0.01, 0.16)	0.12 (0.02, 0.22)	0.14 (−0.42, 0.70)	0.17 (−0.40, 0.73)
	28.0≤BMI<34.9	0.10 (−0.04, 0.23)	0.22 (0.02, 0.42)	0.08 (−0.02, 0.18)	0.16 (0.02, 0.30)	−0.35 (−1.18, 0.49)	−0.38 (−1.23, 0.47)
	BMI≥35.0	0.27 (−0.34, 0.88)	0.18 (−0.70, 1.05)	0.25 (−0.22, 0.72)	0.21 (−0.43, 0.85)	−1.33 (−5.50, 2.85)	−1.27 (−5.65, 3.10)
People with obstructive spirometry	BMI<18.5	−0.76 (−0.91, −0.61)	−0.80 (−0.97, −0.63)	−0.50 (−0.59, −0.40)	−0.53 (−0.64, −0.42)	−2.84 (−3.65, −2.03)	−2.75 (−3.60, −1.90)
	18.5≤BMI<23.9	Ref	Ref	Ref	Ref	Ref	Ref
	24.0≤BMI<27.9	0.21 (0.14, 0.28)	0.27 (0.18, 0.36)	0.00 (−0.01, 0.01)	0.00 (−0.01, 0.01)	2.38 (1.74, 3.01)	2.44 (1.78, 3.11)
	28.0≤BMI<34.9	0.17 (0.06, 0.29)	0.26 (0.12, 0.40)	0.00 (−0.04, 0.03)	0.00 (−0.03, 0.03)	3.80 (2.71, 4.88)	3.90 (2.77, 5.03)
	BMI≥35.0	0.32 (−0.17, 0.82)	0.51 (−0.08, 1.11)	0.00 (−0.05, 0.06)	0.01 (−0.04, 0.06)	7.41 (1.43, 13.39)	8.19 (2.11, 14.26)

Notes: Adjusted model: sex, age, smoke, cough, breath shortness, biofuel use and family history.

Abbreviations: BMI, body mass index; COPD-SQ, the COPD Screening Questionnaire; COPD, Chronic Obstructive Pulmonary Disease; PRISm preserved ratio impaired spirometry; FEV1, the predicted forced expiratory volume in one second; FVC, the Predicted forced vital capacity.

Figure 3 The relationship between BMI and lung function according to lung function test. (A) The relationship between BMI and lung function in people with normal spirometry. (B) The relationship between BMI and lung function in people with PRISm. (C) The relationship between BMI and lung function in people with obstructive spirometry.