Evaluation of the secretin-cholecystokinin test for chronic pancreatitis by discriminant analysis.

Discriminant analysis was used to interpret the results of the secretin-cholecystokinin (CCK) test in the diagnosis of chronic pancreatitis. An allocation rule based on the use of two test variables--mean chymotrypsin concentration and peak bicarbonate output--was constructed to distinguish between 63 patients with chronic pancreatitis and 68 patients without organic disease. These latter patients had signs and symptoms similar to those of the patients with chronic pancreatitis and were used as controls. The allocation rule was applied to a larger set of individuals, including 105 patients with various other diseases. The sensitivity of the test was 83%, and the specificity was 89%. With a prevalence of chronic pancreatitis of 27% in this set of individuals, the positive predictive value was 73%, the negative predictive value was 93%, and the accuracy rate 87%. This diagnostic performance of the secretin-CCK test gives the test a meaningful place in the examination of patients suspected of having chronic pancreatitis.