A Cochrane review included 2 studies with a total of 126 subjects. The outcome measure was symptomatic response. In 49 patients studied, sphincterectomy was more effective than placebo in treating patients with an elevated pressure (OR 9.08, 95% CI 2.97 to 277.77). In 77 patients studied, sphincterectomy was no better than placebo in treating patients with a normal basal pressure (OR 1.28, 95% CI 0.52 to 3.13).
Comment: The quality of evidence is downgraded by imprecise results (few patients and wide confidence intervals).