Ten trials, with about 7,000 patients, were included, but the three smallest trials did not contribute to the analyses. The trials ranged in size from 23 (104 for the fourth trial) to 2,502 patients. Five of the 10 trials were rated as free of bias; two were at risk from one source of bias, and three were at risk from more than one source. The fail-safe N was 17 for stroke and seven for myocardial infarction. Follow-up ranged from 30 days to 66 months.
Nine trials reported strokes within 30 days, but there was moderate statistical heterogeneity (Ι²=49.8%). Four trials reported a high use of cerebral protection devices and meta-analysis of these found that open carotid surgery reduced the rate of stroke at 30 days (RR 0.50, 95% CI 0.38 to 0.67), with no evidence of statistical heterogeneity (Ι²=0). The number needed to treat was 37 (95% CI 29 to 55).
Six trials reported myocardial infarctions within 30 days. Open carotid endarterectomy increased the risk of myocardial infarction at 30 days, compared with stenting (RR 2.16, 95% CI 1.32 to 3.54), with no evidence of statistical heterogeneity (Ι²=0). The number needed to harm was 96 (95% CI 341 to 44).
Seven trials reported deaths within 30 days. There was no difference in the risk of death between the two treatment groups (RR 0.72, 95% CI 0.42 to 1.24; using a random-effects model). There was no evidence of statistical heterogeneity (Ι²=2%).