A total of 141 RCTs (9,559 patients) were included.
Neuraxial blockade significantly reduced overall post-operative mortality within 30 days of randomisation; the OR was 0.70 (95% CI: 0.54, 0.90, P=0.006). No clear difference was observed between different surgical groups. No significant heterogeneity was found (P=0.50.
Spinal and epidural anaesthesia were compared directly in 7 trials that found no difference in mortality (the event rates were very low). The authors then reported indirect comparisons which may be seriously misleading. The results for neuraxial blockade continued post-operatively versus not continued, and for neuraxial blockade combined with general anaesthesia versus neuraxial blockade alone, also appear to be based on indirect comparisons of groups of patients treated in different trials.
Venous thrombosis, cardiac events and stroke.
Deep vein thrombosis (18 RCTs) was significantly reduced with neuraxial blockade (OR 0.56, 95% CI: 0.43, 0.72). Pulmonary emboli (23 RCTs) were significantly reduced with neuraxial blockade (OR 0.45, 95% CI: 0.29, 0.69). Myocardial infarction (30 RCTs) was reduced with neuraxial blockade (OR 0.67, 95% CI: 0.45, 1.00), but the reduction did not reach statistical significance. There was no significant difference in stroke (OR 0.85, 95% CI: 0.46, 1.57).
Bleeding.
Peri-operative transfusion requirements (16 RCTs) significantly reduced with neuraxial blockade; the OR for peri-operative transfusion of greater than 2 units was 0.50 (95% CI: 0.39, 0.66). Post-operative bleeds requiring transfusion (12 RCTs) were significantly reduced with neuraxial blockade (OR 0.45, 95% CI: 0.29, 0.70). No clear differences were found across surgical groups.
Post-operative infection. There was no significant difference in wound infection (14 RCTs); the OR was 0.79 (95% CI: 0.47, 1.33). Pneumonia (28 RCTs) was significantly reduced with neuraxial blockade (OR 0.61, 95% CI: 0.48, 0.76; heterogeneity P=0.05). There was no significant difference in death from other infective causes (6 RCTs); the OR was 0.33 (95% CI: 0.10, 1.07).
Other events.
Respiratory failure (8 RCTs) was significantly reduced with neuraxial blockade (OR 0.41, 95% CI: 0.23, 0.73). There was no significant difference in renal failure (10 RCTs); the OR was 0.57 (95% CI: 0.32, 1.00). Other results were also reported.
The testing of the influence of methodological problems and the type of anaesthesia was hampered by the lack of power to detect even moderate differences.