Serum amyloid A is a better early predictor of severity than C-reactive protein in acute pancreatitis

Background: Serum amyloid A (SAA) is an early and sensitive marker of the extent of tissue trauma and inflammation. The aim of this study was to compare the early prognostic accuracy of SAA with that of serum C-reactive protein (CRP) in acute pancreatitis. Methods: In a prospective multicentre trial, plasma SAA and CRP levels were measured in patients with severe and mild acute pancreatitis, and in a control group with acute abdominal pain. Plasma samples were collected on admission and at 6-h intervals for 48 h, every 12 h between 48 and 72 h, then daily for 5 days. Plasma SAA was measured by a new enzyme-Linked immunosorbent assay and CRP was measured by immunoturbidometry. Results: There were 137 patients with mild and 35 with severe acute pancreatitis, and 74 control patients. SAA levels were significantly higher in patients with severe acute pancreatitis than in those with mild acute pancreatitis, on admission, at 24 h or less after symptom onset, and subsequently. Whereas plasma CRP concentration was also significantly higher in patients with severe acute pancreatitis on admission, it failed to distinguish mild from severe acute pancreatitis until 30-36 h after symptom onset. SAA levels predicted severity (sensitivity 67 per cent, specificity 70 per cent, negative predictive value 89 per cent, mean(s.d.) area under curve 0.7(0.05)) significantly better than CRP (57 per cent, 60 per cent, 84 per cent, 0.59(0.06) respectively) on admission (P = 0.02) and at 24 h following symptom onset (area under curve 0.65(0.09) versus 0.58(0.09) respectively; P less than or equal to 0.02). Conclusion: Plasma SAA concentration is an early marker of severity in acute pancreatitis and is superior to CRP estimation on hospital admission and at 24 h or less after symptom onset. This study suggests that plasma SAA concentration is clinically useful, with the potential to replace CRP in the management of acute pancreatitis.