Value of combinations of pancreatic function tests to predict mild or moderate chronic pancreatitis

Pancreatic function tests share an insufficient accuracy concerning the detection of mild or moderate forms of chronic pancreatitis. It was evaluated here whether by combination of different assays the prediction or exclusion of chronic pancreatitis could be improved.

62 patients with chronic abdominal pain and suspected chronic pancreatitis underwent an endoscopic retrograde pancreaticography. The duct alterations were classified according to the Cambridge criteria. In all individuals the pancreolauryl test in serum (PLT-S) and urine (PLT-U) was performed and elastase 1-immunoreactivity (E) as well as chymotrypsin (Chy) activity in stool were measured. Sensitivities, specificities, receiver-operator-curves as well as cut-off points at optimal accuracies were calculated for each single assay and all test combinations. Cut offs were optimized by a mathematical model to achieve highest accuracies.

In 30 patients the pancreatic duct was normal and in 32 patients alterations of the duct system were found. These were classified as mild in 10 patients, as moderate in 8 patients and as severe in 14 patients. In those with mild and moderate disease all pancreatic function tests showed sensitivities/specificities of 60-65% and 65-70%, respectively. Only in severe chronic pancreatitis elastase was superior to the other tests. Combinations of function tests did not lead to improved accuracy. After mathematical optimization the accuracy (sensitivity 80%, specificity 80%) was best for the combination of PLT-S (cut off 4.7 micrograms/ml) and E (cut off 500 micrograms/g). Both parameters had to be below these newly defined cut offs to diagnose chronic pancreatitis.

The accuracy of pancreatic function tests may be improved by use of altered cut offs and a combination of serum pancreolauryl test and elastase. These newly defined cut offs will have to be evaluated in a much larger study.