Obesity increases the severity of acute pancreatitis: performance of APACHE-O score and correlation with the inflammatory response.

Background: Obese patients appear to be at risk for complications of acute pancreatitis (AP). APACHE-O score has been suggested to improve APACHE-II accuracy in predicting severe outcome in AP.

Aims: To determine if APACHE-O adds any predictive value to APACHE-II score and to test the hypothesis that obese patients are at increased risk of severe AP (SAP) because of a more intense inflammatory response to pancreatic injury.

Methods: 102 AP patients were prospectively studied. Using a body mass index (BMI) >30, 28% of the subjects were obese. Nineteen patients developed organ dysfunction and were classified as SAP. Receiver-operating curves for prediction of SAP were calculated using admission APACHE-II and APACHE-O scores. Binary logistic regression was performed to assess if obesity is a risk for SAP and to determine the clinical factors associated with severe disease. Serum levels of IL-6, MCP-1 and CRP as well as Ranson's scores were compared between obese and non-obese patients.

Results: Admission APACHE-O (area under the curve AUC 0.895) and APACHE-II (AUC 0.893) showed similar accuracy in predicting severe outcome. BMI was identified as a significant risk for SAP (OR 2.8, p = 0.048) and mortality (OR 11.2, p = 0.022). CRP levels were significantly higher in obese AP patients (p = 0.0001) as well as Ranson's score (p = 0.021). IL-6 and MCP-1 levels were higher in obese patients but did not reach statistical significance.

Conclusions: Obesity is an independent risk for SAP. Admission APACHE-O score is not more accurate than APACHE-II. Our study results suggest that obesity increases the severity of AP by amplifying the immune response to injury.