Feature Study
EPISOD study: treatment in patients with suspected Sphincter of Oddi Dysfunction

Dr. Peter B. Cotton is MUSC's Principal Investigator in the NIH-funded study on a treatment for suspected over-activity of the sphincter, a painful dysfunction that can occur following gall bladder surgery.

The sphincter of Oddi is a valve controlling the flow of bile and pancreatic juices into the duodenum. Over-activity of the sphincter can cause recurrent attacks of pain, that feels like the gall bladder pain. Diagnosis and management of this condition is controversial.

Many patients are referred to tertiary centers for Endoscopic Retrograde Cholangiopancreatography (ERCP) with manometry. However, the results of manometry-guided sphincterotomy are not proven and there are significant risks.

The EPISOD study (Evaluating Predictors of Interventions in Sphincter of Oddi Dysfunction), enrolled 214 patients in seven centers in USA (MUSC, Seattle, Minneapolis, Indianapolis, St. Louis, Dallas, and Yale. It was funded by a grant from the National Institutes of Health.

The patients were mainly those previously labeled as "type III SOD", meaning that they had biliary-type pain but no abnormalities detected on imaging of liver blood tests. The goal of the study was to see whether cutting the sphincter at ERCP (sphincterotomy) helped to relieve the pain. To assess this scientifically, the patients (after full education and consent) were assigned randomly (by computer) to undergo sphincterotomy (of the bile duct or pancreatic duct, or both) or no sphincterotomy (sham treatment).

Many patients did improve over the following 12 months of follow-up, but, somewhat to our surprise, those getting sphincterotomy did no better that those with sham treatment. Furthermore, we could not identify any clinical characteristics that predicted a better outcome, and the results of sphincter manometry were also not helpful.

Also noteworthy was the fact that about 15% of patients suffered attacks of acute pancreatitis immediately after the ERCP (all done by experts), emphasizing the known risks.

This study was published in the Journal of the American Medical Association in May 2014 (JAMA. 2014 May 28;311(20):2101-9. doi: 10.1001/jama.2014.5220), and should result in a major change in practice.

There is no doubt that these patients have debilitating pain, but there is no indication for ERCP in this context. Further research is needed to establish the cause and effective treatment.