Meta-analysis and trial sequential analysis of local vs. general anaesthesia for carotid endarterectomy

Controversy exists regarding the best choice of anaesthesia for carotid endarterectomy. We aimed to evaluate the peri-operative outcomes of local vs. general anaesthesia for carotid endarterectomy. We conducted a systematic search of electronic information sources and applied a combination of free text and controlled vocabulary searches adapted to thesaurus headings, search operators and limits in each of the electronic databases. We defined peri-operative stroke, transient ischaemic attack, mortality and myocardial infarction as the primary outcome measures. We identified 12 randomised controlled trials and 21 observational studies reporting a total of 58,212 patients undergoing carotid endarterectomy under local or general anaesthesia. Analysis of observational studies demonstrated that local anaesthesia was associated with a significantly lower incidence of stroke (odds ratio (OR (95% CI) 0.66 (0.55-0.80), p < 0.0001), transient ischaemic attack (0.52 (0.38-0.70), p < 0.0001), myocardial infarction (0.55 (0.41-0.75), p = 0.0002) and mortality (0.72 (0.56-0.94), p = 0.01) compared with general anaesthesia. Analysis of randomised controlled trials did not find a significant difference in the risk of stroke (0.92 (0.67-1.28), p = 0.63), transient ischaemic attack (2.20 (0.48-10.03), p = 0.31), myocardial infarction (1.25 (0.57-2.72), p = 0.58) or mortality (0.61 (0.35-1.05), p = 0.07) between local and general anaesthesia. On trial sequential analysis of the randomised trials, the Z-curve did not cross the α-spending boundaries or futility boundaries for stroke, mortality and transient ischaemic attack, suggesting that more trials are needed to reach conclusive results. Our meta-analysis of observational studies suggests that local anaesthesia for carotid endarterectomy may be associated with lower peri-operative morbidity and mortality compared with general anaesthesia. Although randomised studies have not confirmed any advantage for local anaesthesia, this may be due to a lack of pooled statistical power in these trials.