Fifty-one studies (17,105 operations) were included: 19 prospective and 32 retrospective.
The overall mortality estimate (based on 17,105 operations) was 1.62% (95% CI: 1.3, 1.9) for patients with symptomatic stenosis. The overall risk of stroke and/or death in this group of patients (based on 15,956 operations) was 5.64% (95% CI: 4.4, 6.9). However, significant heterogeneity in the reported risk of stroke and/or death was observed (p<0.001). Among the rest of the included patients, the risk of fatal stroke was 0.86% (95% CI: 0.70, 1.02) and the risk of non-stroke death was 0.7% (95% CI: 0.56, 0.84).
Risks varied systematically with the methods and authorship of the study. The risk of stroke and/or death was highest in studies in which patients were assessed by a neurologist after study, and lowest in studies with a single author affiliated with a department of surgery.
After correcting for differences in study methodology and authorship in a multiple regression analysis, there was no temporal trend in the risk of stroke and/or death between 1980 and 1995.