Suspected sphincter of Oddi dysfunction type II: empirical biliary sphincterotomy or manometry-guided therapy?

Abstract

Sphincter of Oddi manometry is considered to be the gold standard for diagnosing sphincter of Oddi dysfunction (SOD). Elevated basal sphincter pressures are found in about half of the patients with findings consistent with biliary type II SOD, and most of these patients will symptomatically improve after endoscopic sphincterotomy. Since manometric sphincter evaluation is not widely available, a decision analysis was used to compare the overall costs and outcomes of manometry-directed therapy with "empirical" sphincterotomy in patients with suspected biliary type II SOD. A decision analysis model was constructed using a software program. In a hypothetical cohort of 100 patients with suspected type II SOD, the following strategies were evaluated: a). endoscopic retrograde cholangiopancreatography (ERCP) with manometry followed by biliary sphincterotomy only if an elevated sphincter of Oddi basal pressure was found; and b). "empirical" biliary sphincterotomy without manometry. Data on the probability of an elevated sphincter of Oddi basal pressure at the time of ERCP in patients with suspected biliary SOD type II, the proportion of patients who improved after biliary sphincterotomy (with and without elevated basal pressures), the proportion of patients who improved without biliary sphincterotomy, complications, and death were obtained from the literature and from our center. The procedural and hospitalization costs represented the average Medicare reimbursement at our institution. The expected overall costs and numbers of patients improving with each strategy were compared.[nl] The strategy of ERCP with manometry resulted in total costs of US dollars 2790 per patient, whereas a strategy of "empirical" biliary sphincterotomy resulted in total costs of US dollars 2244. In a cohort of 100 patients with suspected SOD, 55 % of patients would be expected to improve if manometry were performed, compared to 60 % of patients improving with "empirical" biliary sphincterotomy. Univariate sensitivity analyses demonstrated that "empirical" biliary sphincterotomy continued to be a cost-saving strategy in comparison with ERCP with manometry as long as the probability of spontaneous improvement in patients with "normal" manometry was less than 41 %, the probability of complications associated with manometry was greater than 6 %, and the probability of complications due to biliary sphincterotomy was less than 19 %. For patients with suspected biliary SOD type II, empirical biliary sphincterotomy performed by experienced endoscopists appears to be cost-saving in comparison with a strategy based on the results of manometry.