Comparison 1. Patch versus no patch: perioperative complications < 30 days.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Any stroke: fatal and non‐fatal	8	1769	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.57 [0.31, 1.03]
1.1 Venous patch	3	346	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.38 [0.08, 1.72]
1.2 Synthetic patch	3	837	Peto Odds Ratio (Peto, Fixed, 95% CI)	1.23 [0.50, 3.07]
1.3 Synthetic or venous patch	2	586	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.29 [0.11, 0.74]
2 Stroke‐related death	7	1441	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.47 [0.05, 4.56]
2.1 Venous patch	3	346	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.91 [0.06, 14.73]
2.2 Synthetic patch	2	509	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.0 [0.0, 0.0]
2.3 Synthetic or venous patch	2	586	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.13 [0.00, 6.46]
3 Stroke ipsilateral to endarterectomy site	7	1201	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.31 [0.15, 0.63]
3.1 Venous patch	3	349	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.39 [0.09, 1.75]
3.2 Synthetic patch	1	100	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.53 [0.05, 5.19]
3.3 Synthetic or venous patch	3	752	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.27 [0.11, 0.62]
4 Death from all causes	9	1869	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.62 [0.18, 2.09]
4.1 Venous patch	3	346	Peto Odds Ratio (Peto, Fixed, 95% CI)	1.79 [0.18, 17.57]
4.2 Synthetic patch	3	837	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.14 [0.00, 7.15]
4.3 Synthetic or venous patch	3	686	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.48 [0.10, 2.24]
5 Any stroke or death	8	1769	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.58 [0.33, 1.01]
5.1 Venous patch	3	346	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.55 [0.13, 2.25]
5.2 Synthetic patch	3	837	Peto Odds Ratio (Peto, Fixed, 95% CI)	1.10 [0.45, 2.69]
5.3 Synthetic or venous patch	2	586	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.34 [0.15, 0.78]
6 Occlusion of the artery operated on	7	1435	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.18 [0.08, 0.41]
6.1 Venous patch	2	255	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.12 [0.01, 1.99]
6.2 Synthetic patch	2	428	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.33 [0.06, 1.95]
6.3 Synthetic or venous patch	3	752	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.16 [0.06, 0.42]
7 Rupture/haemorrhage of endarterectomy site	9	2031	Peto Odds Ratio (Peto, Fixed, 95% CI)	1.24 [0.61, 2.54]
7.1 Venous patch	3	429	Peto Odds Ratio (Peto, Fixed, 95% CI)	6.86 [0.14, 346.63]
7.2 Synthetic patch	3	850	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.92 [0.39, 2.14]
7.3 Synthetic or venous patch	3	752	Peto Odds Ratio (Peto, Fixed, 95% CI)	2.32 [0.56, 9.57]
8 Infection of the endarterectomy site	7	1563	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.38 [0.09, 1.54]
8.1 Venous patch	3	429	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.0 [0.0, 0.0]
8.2 Synthetic patch	2	522	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.38 [0.09, 1.54]
8.3 Synthetic or venous patch	2	612	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.0 [0.0, 0.0]
9 Cranial nerve palsy	4	1047	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.78 [0.36, 1.69]
9.1 Venous patch	1	126	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.77 [0.17, 3.50]
9.2 Synthetic patch	2	522	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.75 [0.24, 2.35]
9.3 Synthetic or venous patch	1	399	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.85 [0.19, 3.71]
10 Complication with return to theatre	7	1281	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.35 [0.16, 0.79]
10.1 Venous patch	3	429	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.98 [0.06, 15.64]
10.2 Synthetic patch	1	100	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.53 [0.05, 5.19]
10.3 Synthetic or venous patch	3	752	Peto Odds Ratio (Peto, Fixed, 95% CI)	0.29 [0.12, 0.73]