Eight studies (n=661) were included in the review: 2 randomised controlled trials (RCTs; n=161), 1 non-randomised prospective study (n=42) and 5 non-randomised retrospective studies (n=458). Three studies reported and analysed anastomotic events, while it appears that the remaining studies reported and analysed events by patient. The meta-analyses were based on all anastomotic events (n=712).
The methodological quality of the included studies was reported. The scores ranged from 5 to 9, with 5 studies scoring 7 points or more.
Short-term complications: anastomotic leak rates were significantly higher for EEA compared with OAC (6 studies; OR 4.37, 95% CI: 1.3, 14.72); there was no significant heterogeneity between the studies. There were no significant differences for any other short-term outcomes.
Post-operative hospital stay: there were no significant differences between the groups (4 studies; WMD 0.88, 95% CI: -1.43, 3.2), although there was significant heterogeneity for this outcome.
Long-term complications: there were no significant differences between the groups for perianastomotic recurrence (3 studies: HR 1.23, 95% CI: 0.52, 2.92) or the need for reoperation (4 studies: HR 1.76, 95% CI: 0.81, 3.83).
Sensitivity analyses showed that in studies reporting on side-to-side anastomosis compared with EEA, a significant difference favouring side-to-side was observed in anastomotic leak (OR 4.37, 95% CI: 1.3, 14.72), overall post-operative complications (OR 2.64, 95% CI: 1.49, 4.67) and post-operative hospital stay (WMD 2.81, 95% CI: 0.79, 4.84). Studies reporting on anastomosis after ileocolonic resection showed a significantly reduced rate of anastomotic leaks (OR 3.8, 95% CI: 1.01, 14.29) for OAC compared with EEA, while no differences were found for other outcomes. Analyses of high-quality studies and of more recent studies (since 2000) did not change the findings.
Evidence of publication bias was identified graphically.