Association of Body Mass Index with Risk of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

Figures & data

Figure 1. Flowchart of the selection of studies included in the meta-analysis.

Table 1. Subgroup analysis of underweight and risk of COPD.

Subgroup	Category	I² (%)	P for I²	OR (95% CI)	P for OR	N
Year	≤2013	17.3	0.085	2.29 (2.03-2.59)	<0.01	12
	>2013	60.4	0.092	1.78 (1.60-1.97)	<0.01	15
	Total	67.3	<0.01	1.96 (1.78–2.17)	<0.01	27
Study type	Cross-section	26.1	0.138	2.10 (1.86–2.37)	<0.01	21
	Cohort	89.1	<0.01	1.79 (1.52–2.12)	<0.01	5
	Total	68.6	<0.01	1.97 (1.78–2.19)	<0.01	26
Gender	Female	82.1	<0.01	2.05 (1.37–3.07)	<0.01	5
	Male	72.3	0.013	3.94 (1.60–9.71)	<0.01	4
	Total	79.3	<0.01	2.22 (1.76–2.80)	<0.01	9
Smoking status	Never smoked	48.3	0.05	2.42 (1.87–3.14)	<0.01	9
	Smoked	0.0	0.827	1.58 (1.26–1.97)	<0.01	4
	Total	53.3	0.011	2.08 (1.67–2.58)	<0.01	13
COPD assessment	GOLD	35.8	0.104	2.08 (1.72–2.52)	<0.01	15
	LLN	39.2	0.200	2.96 (1.32–6.74)	<0.01	2
	Total	77.4	0.028	1.96 (1.78–2.17)	<0.01	19
COPD reported	Spirometry	32.2	0.019	2.13 (1.89–2.41)	<0.01	19
	Questionnaires	0.0	0.635	1.79 (1.54–2.07)	<0.01	4
	Others	88.0	<0.01	1.96 (1.78–2.17)	<0.01	4
	Total	67.3	<0.01	2.00 (1.80–2.23)	<0.01	27
Continent	NA	37.1	0.174	1.87 (1.48–2.38)	<0.01	5
	Asia	74.4	<0.01	1.99 (1.76–2.24)	<0.01	19
	Europe	0.0	0.859	1.85 (1.48–2.30)	<0.01	2
	Total	67.4	<0.01	1.95 (1.77–2.16)	<0.01	26
BMI criteria	China	71.1	<0.01	2.09 (1.81–2.42)	<0.01	13
	WHO	43.0	0.081	1.94 (1.65–2.29)	<0.01	9
	Asia	36.6	0.209	1.61 (1.20–2.16)	<0.01	2
	Others	0.0	0.437	1.80 (1.44–2.26)	<0.01	3
	Total	67.3	<0.01	1.96 (1.78–2.17)	<0.01	27

BMI, body mass index; COPD, chronic obstructive pulmonary disease; GOLD, global initiative for chronic obstructive lung disease; LLN, lower limit of normal; N, number of studies; NA, north America; OR, odds ratio; WHO, World Health Organization.

Figure 2. Forest plot of the odds ratio (ORs) with corresponding 95% confidence intervals (CIs) of the association between underweight and risk of COPD.

Figure 3. Forest plot of the odds ratio (ORs) with corresponding 95% confidence intervals (CIs) of the association between overweight and risk of COPD.

Figure 4. Forest plot of the odds ratio (ORs) with corresponding 95% confidence intervals (CIs) of the association between obesity and risk of COPD.

Table 2. Subgroup analysis of overweight and risk of COPD.

Subgroup	Category	I² (%)	P for I²	OR (95% CI)	P for OR	N
Year	≤2013	38.5	0.087	0.77 (0.70–0.85)	<0.01	14
	>2013	87.4	<0.01	0.81 (0.71–0.91)	<0.01	20
	Total	83.8	<0.01	0.80 (0.73–0.87)	<0.01	34
Study type	Cross-section	83.9	<0.01	0.76 (0.65–0.89)	<0.01	25
	Cohort	85.2	<0.01	0.85 (0.75–0.95)	<0.01	8
	Total	83.7	<0.01	0.79 (0.72–0.87)	<0.01	33
Gender	Female	83.4	<0.01	1.08 (0.88–1.32)	0.447	3
	Male	0.0	0.604	0.91 (0.85–0.98)	<0.01	3
	Total	85.4	<0.01	1.01 (0.88–1.17)	0.865	6
Smoking status	Never smoked	82.1	<0.01	0.88 (0.73–1.05)	0.163	11
	Smoked	45.4	0.139	0.75 (0.66–0.85)	<0.01	4
	Total	85.9	<0.01	0.83 (0.72–0.97)	0.020	15
COPD assessment	GOLD	68.2	<0.01	0.65 (0.54–0.78)	<0.01	14
	LLN	0.0	0.679	0.83 (0.63–1.10)	0.198	2
	Total	63.5	<0.01	0.67 (0.57–0.80)	<0.01	16
COPD reported	Spirometry	67.8	<0.01	0.68 (0.59–0.78)	<0.01	21
	Questionnaires	85.6	<0.01	0.95 (0.85–1.07)	0.853	7
	Others	25.7	0.250	0.94 (0.88–1.01)	0.118	6
	Total	83.8	<0.01	0.80 (0.73–0.87)	<0.01	34
Continent	NA	82.6	<0.01	0.98 (0.85–1.13)	0.798	9
	Asia	71.3	<0.01	0.76 (0.68–0.85)	<0.01	20
	Europe	94.2	<0.01	0.58 (0.38–0.88)	0.010	4
	Total	84.3	<0.01	0.80 (0.73–0.87)	<0.01	33
BMI criteria	China	77.5	<0.01	0.74 (0.64–0.87)	<0.01	13
	WHO	87.2	<0.01	0.86 (0.75–0.99)	0.039	12
	Asia	0.0	0.831	0.91 (0.79–1.04)	0.162	2
	Others	85.6	<0.01	0.73 (0.52–1.02)	0.067	7
	Total	83.8	<0.01	0.80 (0.73–0.87)	<0.01	34
Controls	Non-overweight	94.2	<0.01	0.75 (0.53–1.05)	0.090	7
	Normal weight	67.6	<0.01	0.80 (0.74–0.87)	<0.01	27
	Total	83.8	<0.01	0.80 (0.73–0.87)	<0.01	34

BMI, body mass index; CC, case-control; COPD, chronic obstructive pulmonary disease; CS, cross-section; GOLD, global initiative for chronic obstructive lung disease; LLN, lower limit of normal; NA, north America; OR, odds ratio.

Table 3. Subgroup analysis of obesity and risk of COPD.

Subgroup	Category	I² (%)	P for I²	OR (95% CI)	P for OR	N
Year	≤2013	85.9	<0.01	0.87 (0.69–1.10)	0.245	13
	>2013	89.2	<0.01	0.84 (0.66–1.07)	0.152	12
	Total	89.4	<0.01	0.86 (0.73–1.02)	0.065	25
Study type	Cross-section	89.7	<0.01	0.85 (0.66–1.11)	0.235	18
	Cohort	89.1	<0.01	0.80 (0.63–1.03)	0.091	6
	Total	89.1	<0.01	0.84 (0.70–1.00)	0.046	24
Gender	Female	82.7	0.016	1.66 (0.92–3.00)	0.089	2
	Male	0.0	0.384	0.86 (0.75–1.00)	0.043	2
	Total	90.1	<0.01	1.26 (0.89–1.78)	0.199	4
COPD reported	Spirometry	70.8	<0.01	0.72 (0.61–0.85)	<0.01	17
	Questionnaires	89.1	<0.01	1.08 (0.76–1.53)	0.671	4
	Others	76.6	<0.01	1.43 (0.99–2.05)	0.054	4
	Total	89.4	<0.01	0.86 (0.73–1.02)	0.065	25
Continent	NA	85.2	<0.01	1.27 (0.91–1.76)	0.160	6
	Asia	82.9	<0.01	0.74 (0.62–0.89)	<0.01	16
	Europe	94.5	<0.01	0.79 (0.33–1.87)	0.587	2
	Total	88.7	<0.01	0.86 (0.72–1.01)	0.065	24
BMI criteria	China	85.7	<0.01	0.71 (0.57–0.90)	<0.01	12
	WHO	94.7	<0.01	0.89 (0.59–1.34)	0.578	6
	Others	78.1	<0.01	1.20 (0.82–1.75)	0.342	6
	Total	89.1	<0.01	0.86 (0.73–1.02)	0.086	24
Controls	Non-overweight	79.9	<0.01	1.06 (0.44–2.57)	0.898	3
	Normal weight	89.6	<0.01	0.83 (0.70–0.99)	0.043	22
	Total	89.4	<0.01	0.86 (0.73–1.02)	0.065	25

BMI, body mass index; CC, case-control; COPD, chronic obstructive pulmonary disease; CS, cross-section; GOLD, global initiative for chronic obstructive lung disease; LLN, lower limit of normal; NA, north America; OR, odds ratio.

Figure 5. Influence analysis of the odds ratio (ORs) with corresponding 95% confidence intervals (CIs) of the association between BMI and risk of COPD. (a) underweight. (b) overweight. (c) obesity.

Figure 6. Funnel plot of the odds ratio (ORs) with corresponding 95% confidence intervals (CIs) of the association between BMI and risk of COPD. Each dot represents a different study. (a) Underweight, (b) overweight, (c) obesity.