Eight RCTs (656 patients) and 10 non-randomised studies (4,904 patients) were included. Five trials had a Jadad score of three and one scored two (two trials were abstracts only and did not provide enough information for assessment).
Post-ERCP pancreatitis: Stent placement significantly reduced the odds of pancreatitis (OR 0.22, 95% CI 0.12 to 0.38; eight trials with minimal heterogeneity Ι²=0.3%). There was no evidence of publication bias.
Severity of pancreatitis: All studies used the Cotton et al. criteria for assessing the severity of pancreatitis. Stent placement significantly reduced the odds of mild (OR 0.39, 95% CI 0.20 to 0.76; seven trials with Ι²=0%) as well as moderate pancreatitis (OR 0.19, 95% CI 0.07 to 0.51; seven trials with Ι²=0%). However, although a trend was noted stent placement did not significantly affect severe pancreatitis.
Hyperamylasaemia: Pancreatic stent placement significantly reduced the mean levels of amylase compared with control (weighted mean difference -309.22, 95% CI -350.95 to -267.49; four trials with no significant heterogeneity.
Adverse events: Two trials reported on complications with pancreatic stents. One reported one patient with cholangitis, two with pancreatitis after stent removal and one with guidewire perforation (graded as severe). The other trial did not report any complications.
No significant differences between groups were seen in any subgroup analyses and sensitivity analyses showed similar results to the main analysis. The cumulative meta-analysis showed the efficacy of pancreatic stent placement was established by the publication of the second trial and remained constant with later trials.
Non-randomised studies: All studies except one included high-risk patients and sample sizes varied from 28 to 2,861 patients (further details of the 10 studies were tabulated in the paper). A statistically significant reduction in the incidence of post-ERCP pancreatitis was reported in five studies.