The prognostic value of serum and urine amylase levels and blood count parameters in assessing the risk of post-endoscopic pancreatitis development

Introduction
Detection of post-endoscopic pancreatitis (PEP) in the first hours after endoscopic retrograde cholangiopancreatography (ERCP) can limit its consequences, while excluding it can provide safe discharge of the patient. Therefore, a simple, clinically available test is needed for this purpose. Aim: The assessment of the risk of PEP development based on serum and urine amylase levels and parameters included in blood counts 4 h after ERCP.

Material and methods
The study included 398 patients after therapeutic ERCP. Four hours after the procedure was completed, serum and urine amylase levels and blood count parameters were analysed.

Results
The optimal serum amylase level for PEP detection was 516 UI/l, with ACC = 0.94, sens. 77.8%, spec. 0.95; positive predictive value (PPV) 0.412, negative predictive value (NPV) 0.98, positive likelihood factor (LR+) 14.93, and negative likelihood factor (LR–) 0.23. The serum amylase level for exclusion of PEP was 184 UI/l with ACC 0.79, sens. 0.83, spec. 0.79, PPV 0.16, NPV 0.99, and LR– 0.21. The optimal urine amylase level for detection and exclusion (based on Youden index) was 575 UI/l, sens. 83.33%, spec. 81.3%, PPV 0.172, NPV 0.99, LR+ 4.44, and LR– 0.20.

Conclusions
Serum amylase levels above 516 UI/l at 4 h after ERCP should be an indication for further observation in hospital, and levels below 184 UI/l may justify safe discharge of the patient. Additional determinations of urine amylase levels and parameters included in blood counts do not improve the diagnostic capacity for the detection or exclusion of PEP risk.