Early Serum Biomarkers for Severity Stratification in Patients with Acute Pancreatitis: A Review

Abstract

Roughly one patient in five with acute pancreatitis develops severe disease, and mortality in that group approaches thirty per cent. Identifying them on the first day is the point of severity stratification. Decades of biomarker work have produced a large literature and, on the evidence reviewed here, no marker that clearly outperforms a routine blood urea nitrogen measurement. Objectives: To review the published evidence on early serum biomarkers for severity stratification in acute pancreatitis: what C-reactive protein, procalcitonin and the cytokines achieve, how they compare with routine laboratory values and with established multifactor scores, and why the timing of measurement determines the answer. Material and Methods: Narrative review of prospective cohorts, comparative accuracy studies, pooled analyses and consensus classifications indexed in PubMed and the major gastroenterology and critical care journals. Studies were eligible if they reported the accuracy of a serum marker or clinical score for predicting severity, organ failure, infected necrosis or mortality in a defined population with acute pancreatitis. No new patient data were generated; every estimate quoted is one published by the original investigators. Results: In 410 prospectively enrolled patients, the rise in blood urea nitrogen at 24 hours predicted mortality with an area under the curve of 0.842 and persistent multiorgan failure at 0.828, comparable to the BISAP score (0.836 and 0.850) and better than APACHE-II (0.756 and 0.741). For severe pancreatitis specifically, BISAP outperformed both, at 0.873 against 0.756 for the urea rise and 0.761 for APACHE-II. Rise in urea was the only variable independently associated with mortality on multivariable analysis, with an odds ratio of 12.7 (95% CI 4.2-16.6). C-reactive protein has a conventional threshold of 150 mg/L at 48 hours, but its discrimination is poor before 72 hours and improves substantially only afterwards, by which time the clinical
question has usually answered itself. Conclusion: The constraint in this field is timing rather than the choice of analyte. The inflammatory markers with the best reported accuracy become informative at 48 to 72 hours, while the decision they are meant to inform is made on admission. Routine values available within the first day perform as well as more elaborate alternatives and should be used in preference to waiting. Abbreviations: AP – Acute Pancreatitis, SAP – Severe Acute Pancreatitis, BUN – Blood Urea Nitrogen, CRP – C-Reactive Protein, PCT – Procalcitonin, IL-6 – Interleukin 6, BISAP – Bedside Index of Severity in Acute Pancreatitis, APACHE-II – Acute Physiology and Chronic Health Evaluation II, CTSI – Computed Tomography Severity Index, PASS – Pancreatitis Activity Scoring System, HAPS – Harmless Acute Pancreatitis Score, AUC – Area Under the Receiver Operating Characteristic Curve, POF – Persistent Organ Failure.