Several different factors estimate the risk of a severe course and death in patients with acute pancreatitis, and they fall into clinical, laboratory and radiological groups. None of them is accurate on its own, so they are read together.
Among the clinical predictors, older age is consistent but imprecise: different studies use cutoffs from 55 to 75, and the older the patient, the higher the chance of death during the first two weeks after the attack. Alcohol-associated pancreatitis, a short interval between the onset of symptoms and admission, and obesity also raise the risk. Early and prolonged organ failure is the clinically useful one: in one study the presence of organ failure within 72 hours of admission was associated with a higher mortality rate and more pancreatic complications, and what matters most is its persistence — persistent or even deteriorating organ failure carries a higher risk of mortality, while improving organ failure is associated with a 0% mortality rate. It is therefore better to say that early and persistent or deteriorating organ failure predicts severity and mortality.
The laboratory predictors mostly reflect the haemoconcentration and inflammatory response of the disease:
- Haemoconcentration — acute pancreatitis causes significant third-space volume loss, which raises the haematocrit and concentrates the blood, so it is one of the laboratory predictors of severity.
- CRP — one cutoff discriminates mild from severe disease: 150 mg/L at 48 hours after admission.
- BUN — for every 5 mg/dL rise during the first 24 hours of admission, the odds ratio for mortality increases by 2.2.
- Serum creatinine — a low or normal level during the first 48 hours of admission has a high negative predictive value for pancreatic necrosis.
Among the radiological predictors, pleural effusion, pulmonary infiltrate, or both during the first 24 hours of admission are associated with a higher risk of pancreatic necrosis and organ failure. CT is the imaging modality most often used to assess patients suspected of severe acute pancreatitis.
Several scoring systems have been built from these predictors, but they share two problems: they can be applied only 48 hours after admission, and they assess severity imperfectly, with wide variation between institutions in how they are used. Ranson’s criteria is one of the first, with 11 factors split between those measured at admission and those measured after 48 hours. The most widely studied system is APACHE II, an ICU score for critically ill patients that uses 12 points for different physiological values and has a good negative but only modest positive predictive value for severity.