The "Two-Step" approach for classifying the severity of acute pancreatitis: a retrospective study.

BACKGROUND The Revised Atlanta Classification (RAC) and Determinant-Based Classification (DBC) are currently two widely adopted systems for evaluating the severity of acute pancreatitis (AP). This study aimed to overcome the inaccuracies and limitations that existed in them. METHODS We retrospectively analyzed 298 patients with AP. The "Two-Step" approach was divided into an early organ failure (OF) assessment: (I) none, (II) transient, (III) single persistent, and (IV) multiple persistent; and a later local complications assessment: (A) none, (B) sterile, and (C) infectious. Patients with AP who died before the second step were classified into category X. The "Two-Step" approach was then compared to the RAC and DBC. RESULTS As the patients' grades increased (I to IV), organ support treatment rates, intensive care unit lengths of stay, and mortalities increased. Invasive intervention rates displayed increasing trends with local complications aggravated (A to C). Patients in category X were older and had higher Marshall scores with the highest grades of severity. CONCLUSIONS By combining the early OF grades and the late local complications, the "Two-Step" approach represents an accurate classification system required for stratified studies of AP, and introduces the category X as the severest forms of AP.