Table 7. Exploration of heterogeneity on 3- and 5-year survival probabilities. Meta-regression results (P values and reduction in I²) from studies concerning the impact of combined or staged surgical procedures on postoperative outcome of patients operated for both primary lung cancer and heart disease co-morbidity (second meta-analysis).

Postoperative outcome	Number of studies	P value	Initial I2 (%)	Residual I2 (%)
3-year survival (%)
Mean age	7	0.454	71.24	72.52
% males	7	0.200	71.24	61.59
% squamous	8	0.221	80.24	81.49
% adenocarcinoma	7	0.336	82.08	80.32
% pneumonectomy	6	0.768	82.40	85.83
% lobectomy	8	0.965	80.24	82.77
% p-N0 or N1	6	0.643	72.00	77.52
% p-T1 or T2	7	0.551	82.08	85.00
% extracorporeal circulation	8	0.121	80.24	77.94
% CABG	8	0.856	80.24	82.87
5-year survival (%)
Mean age	7	0.046	85.63	76.56
% males	7	0.305	85.63	81.97
% squamous	6	0.300	87.67	85.78
% adenocarcinoma	6	0.183	87.67	87.40
% pneumonectomy	4	0.407	72.67	73.09
% lobectomy	7	0.009	85.63	50.51
% p-N0 or N1	3	0.373	79.62	75.87
% extracorporeal circulation	7	0.726	85.63	86.49
% CABG	7	0.901	85.63	87.67

CABG, aorto-coronary bypass grafting.