AIM:To determine if serum inter-cellular adhesion molecule 1(ICAM-1)is an early marker of the diagnosis and prediction of severe acute pancreatitis(SAP) within 24 h of onset of pain,and to compare the sensitivity,specificity and prognostic value of this test with those of acute physiology and chronic health evaluation(APACHE)Ⅱscore and interleukin-6(IL-6). METHODS:Patients with acute pancreatitis(AP)were divided into two groups according to the Ranson’s criteria:mild acute pancreatitis(MAP)group and SAP group.Serum ICAM-1,APACHEⅡand IL-6 levels were detected in all the patients.The sensitivity,specificity and prognostic value of the ICAM-1,APACHEⅡscore and IL-6 were evaluated. RESULTS:The ICAM-1 level in 36 patients with SAP within 24 h of onset of pain was increased and was significantly higher than that in the 50 patients with MAP and the 15 healthy volunteers(P<0.01).The ICAM-1 level(25 ng/mL)was chosen as the optimum cutoff to distinguish SAP from MAP,and the sensitivity,specificity,positive predictive value,negative predictive value(NPV),positive likelihood ratio and negative likelihood ratio were 61.11%,71.42%,0.6111,0.7142, 2.1382 and 0.5445,respectively.The area under the curve demonstrated that the prognostic accuracy of ICAM-1(0.712)was similar to the APACHE-Ⅱscoring system(0.770)and superior to IL-6(0.508)in distinguishing SAP from MAP. CONCLUSION:ICAM-1 test is a simple,rapid and reliable method in clinical practice.It is an early marker of diagnosis and prediction of SAP within the first 24 h after onset of pain or on admission.As it has a relatively low NPV and does not allow it to be a stand-alone test for the diagnosis of AP,other conventional diagnostic tests are required. AIM: To determine if serum inter-cellular adhesion molecule 1 (ICAM-1) is an early marker of the diagnosis and prediction of severe acute pancreatitis (SAP) within 24 h of onset of pain, and to compare the sensitivity, specificity and prognostic value of this test with those of acute physiology and chronic health evaluation (APACHE) IIscore and interleukin-6 (IL-6). METHODS: Patients with acute pancreatitis (AP) were divided into two groups according to the Ranson’s criteria: mild acute pancreatitis (MAP) group and SAP group. Serum ICAM-1, APACHE II and IL-6 levels were detected in all the patients. Sensitivity, specificity and prognostic value of the ICAM-1, APACHE II scale and IL- -1 level in 36 patients with SAP within 24 h of onset of pain was increased and was significantly higher than that in the 50 patients with MAP and the 15 healthy volunteers (P <0.01). The ICAM-1 level (25 ng / mL ) was chosen as the optimum cutoff to distinguish SAP from MAP, and the sensitivity, spec positive predictive value, negative predictive value (NPV), positive likelihood ratio and negative likelihood ratio were 61.11%, 71.42%, 0.6111,0.7142, 2.1382 and 0.5445, respectively. The area under the curve demonstrated that the prognostic accuracy of ICAM- 1 (0.712) was similar to the APACHE-II scoring system (0.770) and superior to IL-6 (0.508) in distinguishing SAP from MAP. CONCLUSION: ICAM-1 test is a simple, rapid and reliable method in clinical practice. an early marker of diagnosis and prediction of SAP within the first 24 h after onset of pain or on admission. As it has a relatively low NPV and does not allow it to be stand-alone test for the diagnosis of AP, other conventional diagnostic tests are required.