Prospective comparison of radial and linear endoscopic ultrasound for diagnosis of chronic pancreatitis

BACKGROUND AND STUDY AIMS

Linear endoscopic ultrasonography (EUS) is currently favored by many endosonographers for the evaluation of pancreatic pathology. However, radial EUS was used in early studies validating EUS for chronic pancreatitis. Radial and linear EUS have never been compared for the diagnosis of chronic pancreatitis. The aim of this study was to compare radial and linear EUS for the diagnosis of chronic pancreatitis using the secretin-stimulated endoscopic pancreatic function test (ePFT) as the reference standard.

PATIENTS AND METHODS

One hundred consecutive patients evaluated for pain of possible pancreatic origin underwent combined radial EUS, linear EUS, and secretin ePFT during a single endoscopic session. EUS images were acquired on videotape and blindly scored by three reviewers. The main outcome measure was diagnostic accuracy.

RESULTS

The accuracy of radial EUS and linear EUS (cutpoint > or = 4 criteria) was 84 % and 74 %, respectively. The statistical test for noninferiority was significant ( P < 0.001) suggesting that the accuracy of radial EUS is as good as or superior to linear EUS. The ratio of accuracy (pi (radial)/pi (linear)) was 1.14 (95 % confidence interval [CI] 0.99 to 1.28). No statistically significant differences were found between radial and linear EUS in terms of sensitivity, specificity, or overall discriminative ability (area under receiver operating characteristic curve 0.84 vs. 0.76, P = 0.10). Interobserver variability was similar for radial (Fleiss' kappa = 0.61, 95 %CI 0.43 to 0.79) and linear EUS (kappa = 0.50, 95 %CI 0.28 to 0.72).

CONCLUSIONS

The accuracy of radial EUS is as good as linear EUS for the diagnosis of chronic pancreatitis.

A randomized controlled crossover study comparing synthetic porcine and human secretins with biologically derived porcine secretin to diagnose Zollinger-Ellison Syndrome

BACKGROUND

Although biologically-derived porcine secretin is approved for the diagnosis of Zollinger-Ellison Syndrome, it is no longer available in the United States. Pure human and porcine secretins have now been synthesized and new drug applications have been filed with the Federal Drug Administration (FDA).

METHODS

In the current study we compared secretin testing results in six confirmed Zollinger-Ellison Syndrome patients using the biologically-derived product and both synthetic products (human and porcine) in a three-way, randomized, single-blind Latin-squares crossover study.

RESULTS

Using the FDA-approved criterion for positive secretin testing (i.e. a serum gastrin concentration increase of > 110 pg/mL), there was complete agreement between all three agents for all patients. With the more stringent NIH criterion (i.e. a serum gastrin concentration increase of > 200 pg/mL), positive results persisted in five out of six, six out of six and four out of six patients using biologically-derived secretin, synthetic porcine secretin, and synthetic human secretin, respectively (six out of six, six out of six and four out of six if a positive test was defined as a 50% increase in serum gastrin concentration). The time to peak serum gastrin concentration after secretin injection occurred within 15 min in all studies (in 94% by 10 min and in 77% by 5 min). Three-way comparisons of serum gastrin concentrations showed a single statistically significant difference (the change from baseline at 15 min between synthetic human and synthetic porcine secretin, P=0.0274). Statistically significant changes from baseline occurred at 1, 2 and 5 min for biologically-derived porcine secretin and at 2 and 5 min for both synthetic porcine and synthetic human secretin, in keeping with the expected time curve for positive tests. All three agents were well-tolerated.

CONCLUSIONS

These data suggest that either synthetic secretin product, when released onto the United States market, can be used to confirm Zollinger-Ellison Syndrome.

Evaluation of basket and paddle dissolution methods using different performance standards

Dissolution studies using both basket and paddle methods were carried out to evaluate two prednisone standards. Results of the experiments showed that the USP prednisone calibrator is sensitive to perturbations by the basket method but not to perturbations by the paddle method. However, the National Center for Drug Analysis (NCDA) prednisone performance standard is sensitive to perturbations by the paddle method but not to perturbations by the basket method. These results suggest that no single standard can predict the suitability of the dissolution equipment by the basket and paddle methods.