Sphincterotomy for biliary sphincter of Oddi disorder and idiopathic acute recurrent pancreatitis: the RESPOnD longitudinal cohort.

Objective: Sphincter of Oddi disorders (SOD) are contentious conditions in patients whose abdominal pain, idiopathic acute pancreatitis (iAP) might arise from pressurisation at the sphincter of Oddi. The present study aimed to measure the benefit of sphincterotomy for suspected SOD.

Design: Prospective cohort conducted at 14 US centres with 12 months follow-up. Patients undergoing first-time endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy for suspected SOD were eligible: pancreatobiliary-type pain with or without iAP. The primary outcome was defined as the composite of improvement by Patient Global Impression of Change (PGIC), no new or increased opioids and no repeat intervention. Missing data were addressed by hierarchal, multiple imputation scheme.

Results: Of 316 screened, 213 were enrolled with 190 (89.2%) of these having a dilated bile duct, abnormal labs, iAP or some combination. By imputation, an average of 122/213 (57.4% (95% CI 50.4% to 64.4%)) improved; response rate was similar for those with complete follow-up (99/161, 61.5% (54.0% to 69.0%)); of these, 118 (73.3%) improved by PGIC alone. Duct size, elevated labs and patient characteristics were not associated with response. AP occurred in 37/213 (17.4%) at a median of 6 months post ERCP and was more likely in those with a history of AP (30.9% vs 2.9%, p<0.0001).

Conclusion: Nearly 60% of patients undergoing ERCP for suspected SOD improve, although the contribution of a placebo response is unknown. Contrary to prevailing belief, duct size and labs are poor response predictors. AP recurrence was common and like observations from prior non-intervention cohorts, suggesting no benefit of sphincterotomy in mitigating future AP episodes.