1. Risk of death and stroke or death within 30 days after surgery, by the degree of carotid stenosis.

	NASCET 1991		ECST 1998		VACSP 1991		Total		P* value
Outcome: stroke or death
< 50% stenosis	43/663	6.5% (4.7 to 8.6)	73/1044	6.9% (5.4 to 8.6)	0/0	‐	116/1707	6.7% (5.6 to 8.0)	0.52
50% to 69% stenosis	30/421	7.1% (4.8 to 10.0)	37/371	10.0% (6.9 to 13.1)	2/20	10.0% (1.2 to 3.2)	69/812	8.4% (6.6 to 10.5)	0.16
> 70% stenosis	14/261	5.4% (3.0 to 8.8)	17/249	6.8% (4.0 to 10.7)	5/71	7.0% (2.3 to 15.7)	36/581	6.2% (4.4 to 8.5)	0.58
Near‐occlusion	5/70	7.1% (2.4 to 15.0)	3/78	3.8% (0.8 to 10.8)	0/0	‐	8/148	5.4% (2.4 to 10.4)	0.48
Total	92/1415	6.5% (5.3 to 7.9)	130/1742	7.5% (6.3 to 8.8)	7/91	7.7% (3.1 to 15.2)	229/3248	7.1% (6.3 to 8.1)	0.30
Outcome: death
< 50% stenosis	7/663	1.1% (0.4 to 2.2)	10/1044	0.9% (0.5 to 1.7)	0/0	‐	17/1707	1.0% (0.6 to 1.6)	0.80
50% to 69% stenosis	6/421	1.4% (0.5 to 3.1)	6/371	1.5% (0.6 to 3.3)	0/20	0% (0 to 16.8)	12/812	1.4% (0.8 to 2.5)	0.83
> 70% stenosis	1/261	0.4% (0 to 2.1)	1/249	0.4% (0 to 12.2)	3/71	4.2% (0.8 to 11.9)	5/581	0.9% (0.3 to 2.0)	0.97
Near‐occlusion	1/70	1.4% (0 ‐ 7.7)	0/78	0% (0 ‐ 4.6)	0/0	‐	1/148	0.7% (0 ‐ 3.7)	0.29
Total	15/1415	1.1% (0.6 to 1.7)	17/1742	1.0% (0.6 to 1.6)	3/91	3.3% (0.7 to 9.3)	35/3248	1.1% (0.8 to 1.5)	0.86

Data are number of events/number of patients, and percentage risk (95% confidence interval)
*Heterogeneity