Table 3. Meta-analysis of the association between COPD and risk of BPF after lung cancer surgery.

Groups of outcomes	N	Enrolled samples			Heterogeneity (I2, P)	Model	OR with 95% CI	P value	Publication bias		Conclusion
		Total	COPD	BPF					Begg (P)	Egger (P)
Overall	8	4,149	1,127	163	39.0%, 0.12	Fixed	2.03 (1.44–2.86)	<0.001	0.90	0.89	Significant
Statistical analysis1
Univariate analysis	8	4,149	1,127	163	20.9%, 0.26	Fixed	1.91 (1.35–2.69)	<0.001	0.90	0.79	Significant
Multivariate analysis	3	1,296	315	83	0.0%, 0.42	Fixed	3.18 (1.95–5.19)	<0.001	0.30	0.19	Significant
Operative modes
Pneumonectomy	6	2,444	686	131	49.4%, 0.08	Random	2.11 (1.15–3.87)	0.016	0.71	0.76	Significant
Lobectomy	Given up because of the scarcity of available data
The origins of patients
Asian	2	2,145	603	57	0.0%, 0.65	Fixed	1.48 (0.85–2.57)	0.16	1.0	NI	Not significant
Non-Asian	6	2,004	524	106	45.8%, 0.10	Random	2.36 (1.18–4.73)	0.016	1.0	0.77	Significant

¹, all the included studies reported demographics or statistics derived from univariate analysis. The OR with 95% CI from multivariate analysis was reported in Ref (16,20,21). BPF, bronchopleural fistula; CI, confidence interval; COPD, chronic obstructive pulmonary disease; N, reference count; NI, no information; OR, odds ratio.