ObjectiveTo investigate correlation of bedside index for severity in acute pancreatitis(BISAP) and computed tomography severity index(CTSI), modified computed tomography severity index(MCTSI), or extra-pancreatic inflammation on CT(EPIC) score, respectively, in assessing severity of acute pancreatitis. MethodsForty-five patients confirmed SAP from July 2015 to November 2015 in West China Hospital of Sichuan University were prospectively included into this study. Contrast-enhanced multi-detector-row CT scan was performed for all the patients. The abnormal imaging features, such as pancreatic and peri-pancreatic inflammatory changes, involvement of other organs and local complications, were observed and used to calculate three CT severity indexes(CTSI, MCTSI, and EPIC). The clinical data were also colle-cted to calculate BISAP and as compared with CT severity indexes. Correlation between the CT indexes points and BISAP score was estimated using the Spearman test. Interobserver agreement for CTSI, MCTSI or EPIC was calculated using the Kappa statistic. ResultsThe results of BISAP score were as follows: 4 cases gradeⅠ, 22 cases gradeⅡ, 19 cases gradeⅢ. The results of CTSI score were as follows: 6 cases gradeⅠ, 22 cases gradeⅡ, 17 cases gradeⅢ. The results of MCTSI score were as follows: 1 case gradeⅠ, 13 cases gradeⅡ, 31 cases gradeⅢ. The results of EPIC score were as follows: 6 cases gradeⅠ, 11 cases gradeⅡ, 28 cases gradeⅢ. The score of BISAP, CTSI, MCIST, or EPIC was 2.41±0.82, 6.02±1.96, 7.91± 2.11, and 5.57±1.52, respectively. Interobserver agreements for CTSI, MCTSI, and EPIC were good(CTSI: Kappa=0.748, 95% CI 0.000-0.076, P < 0.01; MCTSI: Kappa=0.788, 95% CI 0.000-0.076, P < 0.01; EPIC: Kappa=0.768, 95% CI 0.000-0.076, P < 0.01). Spearman statistic showed there was a positive correlation between CTSI score(rs=0.439, P=0.003), MCTSI score(rs=0.640, P=0.000), or EPIC(rs=0.503, P=0.001) and BISAP score. ConclusionThere is a positive correlation between MCTSI or EPIC and BISAP score, and MCTSI is more strongly correlated with BISAP as compared with EPIC.