Acute pancreatitis (AP) is a disease characterized by dysfunction of pancreatic acinar cells, improper activation of trypsin, and subsequent destruction of pancreatic self-defense mechanisms, further exacerbating injury and damage of pancreatic cells. It is a rapidly developing inflammatory process of the pancreas, and the most common reasons are alcohol and gallstones.

As one of the most common gastrointestinal diseases in hospitalized patients, the incidence of AP has gradually increased and is 4.9 to 73.4 cases per 100,000 people worldwide in the past few decades, imposing a heavy burden on the health system and leading to long-term hospitalization, most medical costs, and significant mortality.

Up to 10% to 20% of AP patients will develop SAP, and the leading cause of poor prognosis in patients with AP is a vital organ (cardiovascular organs, lung, and kidney) failure and pancreatic necrosis . In clinical practice, varieties of scoring systems are available and have been gradually confirmed, such as the Ranson score, Glasgow score, Acute Physiology and Chronic Health Evaluation (APACHE II), BISAP, and computed tomography severity index (CTSI) . These systems are cumbersome and take a long time to operate, requiring a lot of parameters that are not routinely collected in the early stages of the disease. For example, the BISAP score is characterized by high specificity, but its sensitivity to SAP is not satisfied. Therefore, their early prediction power is not good.

In AP, inflammation first activates a series of inflammatory cytokines, proteolytic enzymes, and anaerobic radioactive nucleic acids to destroy the tissue. The degree of neutrophils decrease is related to the improvement of prognosis of AP, while the degree of lymphocyte increase is related to the severity of the disease. The neutrophil-lymphocyte ratio (NLR) is a more comprehensive biomarker that used neutrophil and lymphocyte counts to respond rapidly to the extent of inflammatory progression and serves as a useful predictive marker to identify the severity of AP. It is well known that AP is a fast-onset inflammation of the pancreas, and an effective prediction of the severity of AP can guide AP patients to receive adequate treatment earlier, contributing to a better prognosis.

Inclusion Criteria:

• patients with acute pancreatitis

Exclusion Criteria:

• Patients with acute abdomen with diagnosis other than AP
• Patients with AP who are under age of 18 years old
• Patient's refusal

Any patient who is above age of 18 years old and diagnosed to have AP. Patients were diagnosed with acute pancreatitis if more than 2 of the following conditions were satisfied: 1) abdominal pain consistent with acute pancreatitis (acute onset of a persistent, severe, epigastric pain often radiating to the back); 2) serum amylase and/or lipase level at least 3 times greater than the upper limit of the normal value; and 3) characteristic manifestation of acute pancreatitis on contrast-enhanced computed tomography, magnetic resonance imaging, or transabdominal ultrasonography

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