The following characteristics between the two groups did not differ significantly (P > 0.05): (1) Patient demographics: sex, age, BMI, smoking and drinking histories, history of AP, and pancreatitis aetiology; (2) The severity of illness: CTSI, BISAP, maximum size in cross section of WON, WBC and CRP at baseline; and (3) Preoperative relevant data: previous invasive intervention (ETD/PCD), the culture of blood and cystic fluid. The gene discussed is CRP; the disease is alkaline phosphatase measurement.