Table 4. Exploration of heterogeneity on 30-day postoperative mortality and postoperative complications proportions. Meta-regression results (P values and reduction in I²) from studies concerning the impact of perioperative management on postoperative outcome of patients operated for primary lung cancer (first meta-analysis).

Postoperative outcome	Number of studies	P value	Initial I2 (%)	Residual I2 (%)
30 days mortality (%)
Mean age	12	0.761	64.00	66.07
% males	13	0.571	64.68	67.34
% squamous	11	0.001	82.75	24.15
% adenocarcinoma	11	0.323	82.75	83.34
% pneumonectomy	13	0.868	75.39	72.91
% lobectomy	13	<0.001	79.77	18.21
% p-N0 or N1	6	0.178	8.07	0.00
Complications (%)
Mean age	13	0.130	96.43	95.51
% males	14	0.296	96.19	95.77
% squamous	11	0.631	94.80	95.05
% adenocarcinoma	11	0.785	94.80	94.32
% pneumonectomy	13	0.724	96.26	96.53
% lobectomy	10	0.789	97.55	97.13
% p-N0 or N1	8	0.373	85.53	84.19