A Model to Predict the Severity of Acute Pancreatitis Based on Serum Level of Amylase and Body Mass Index

Abstract

Background & aims: Most patients with acute pancreatitis (AP) develop mild disease, but up to 20% develop severe disease. Many clinicians monitor serum levels of amylase and lipase in an attempt to predict the disease course, but this strategy has not been recommended by practice guidelines. We performed a retrospective analysis to determine whether the percentage changes in amylase and lipase were associated with the severity of disease that developed in patients with AP.

Methods: We analyzed data collected from 182 consecutive patients with AP (21 with severe AP) admitted to the Cleveland Clinic from January 2008 through May 2010 (discover cohort). The association between 11 different factors and the severity of AP were assessed by univariable analysis; multivariable models were explored through stepwise selection regression. The percentage change in the serum level of amylase was calculated as follows: ([amylase day 1 - amylase day 2]/amylase day 1) × 100. The percentage change in amylase and body mass index (BMI) were combined to generate a z-score (z = -5.9 + [0.14 × BMI] + [0.01 × percentage change in amylase]), which was converted into a probability distribution called the change in amylase and BMI (CAB) score. The CAB score was validated using the AP database at the University of Pittsburgh Medical Center (140 patients, 35 with severe AP); we calculated p-scores for each patient and estimated the area under the receiver operating characteristics curve values.

Results: Univariable analysis identified the percentage change in the serum level of amylase and other factors to be associated significantly with the severity of AP (P = .017). The CAB score was best at identifying patients who developed severe AP, with an area under the receiver operating characteristics curve value of 0.79 in the discovery cohort (95% confidence interval, 0.71-0.87) and 0.731 in the validation cohort (95% confidence interval, 0.61-0.84).

Conclusions: We developed a model to identify patients most likely to develop severe AP based on the percentage changes in serum level of amylase during the first 2 days after admission to the hospital and BMI.

Keywords: Inflammation; Pancreas; Prognosis; Risk Factor; Scoring System.