Prospective evaluation of the accuracy of the intraductal secretin stimulation test in the diagnosis of chronic pancreatitis

Background & Aims: The standard secretin stimulation test (SST) is the accepted gold standard for pancreatic function testing. The intraductal secretin stimulation test (IDST) performed at the time of endoscopic retrograde cholangiopancreatography (ERCP) has been proposed as a more feasible way to evaluate pancreatic function. The accuracy of the IDST for the diagnosis of chronic pancreatitis (CP) has not been well defined. Methods: We prospectively evaluated patients with suspected CP. The IDST, SST, and ERCP were performed in each of the 19 study patients. The SST and ERCP were used as independent diagnostic standards against which the results of the IDST were compared directly to determine the sensitivity, specificity, and accuracy of the IDST. Results: When the SST was used as a diagnostic standard for CP, the sensitivity of the IDST was 80% (95% confidence interval [Cl], 44%-97%), the specificity was 22% (95% Cl, 2%-.60%), and the overall accuracy was 52% (95% Cl, 28%-75%). The positive predictive value was 53% and the negative predictive value was 50%. When the pancreatogram was used as the diagnostic standard, the sensitivity of the IDST was 100% (95% Cl, 69%-100%), the specificity was 55% (95% Cl, 21%-86%), and the overall accuracy was 79% (95% Cl, 54%-93%). Receiver operator curves showed that there was no optimal cut-off value for peak bicarbonate concentration that led to acceptable sensitivity and specificity. Conclusions: The IDST is not accurate for the diagnosis of CP.