ESTES PARK, COLO. – With acute pancreatitis now accounting for more than 300,000 hospital admissions per year, it behooves physicians to be adept at early clinical diagnosis and familiar with the newer, user-friendly tools for estimating case severity.
These tasks have been made much easier as a result of the simplified Atlanta consensus diagnostic criteria of 2012 and the development of a couple of quick triage tools – the HAPS and BISAP – which are far better suited for this purpose than the old Ranson criteria and APACHE-II (Acute Physiology and Chronic Health Examination) score, Dr. Peter R. McNally said at a conference on internal medicine sponsored by the University of Colorado.
Dr. Peter R. McNally
"Since we solved the riddle of H. pylori and peptic ulcer disease, acute pancreatitis has become the number one GI diagnosis for admission to the hospital," noted Dr. McNally, chief of gastroenterology at Evans Army Hospital in Fort Carson, Colo.
The revised criteria for clinical diagnosis of acute pancreatitis developed by an international panel meeting in Atlanta (Gut 2013;62:102-11) require that two of three criteria be met: typical pain; a serum amylase and/or lipase level at least three times the upper limit of normal; and demonstration of the characteristic findings of acute pancreatitis on imaging, with computed tomography getting the nod as the best imaging modality. However, there are sound reasons for delaying CT imaging until at least the 48-hour mark in most cases. Thus, as a practical matter, early diagnosis requires both typical pain and enzyme elevations.
"The pancreas is located deep in the retroperitoneum. It sits on thoracolumbar vertebrae T12/L1. I want to emphasize that if you have pancreatitis, you have back pain. If you don’t have back pain, just anterior abdominal pain, it’s not pancreatitis," Dr. McNally said.
The classic picture of acute pancreatitis is acute onset of 10/10 pain. When the physician walks into the examination room, the patient is typically in the fetal position in order to relieve the excruciating back pain.
Eighty percent of cases of acute pancreatitis are mild and usually edematous. The other 20% are severe and usually necrotic. Mortality is 3% or less with edematous cases and 15%-25% or more with necrotic pancreatitis.
The HAPS and BISAP scores are enormously helpful in assessing severity early on, unlike the Ranson criteria and APACHE-II score, which are tedious and complicated, and take up to 48 hours to complete, the gastroenterologist observed.
The HAPS (Harmless Acute Pancreatitis Score) can be measured within 30 minutes of hospital admission. There are three criteria for a "harmless" HAPS score: a normal hematocrit, normal serum creatinine, and absence of rebound tenderness. The presence of all three criteria has 96% specificity and 99% positive predictive value for a nonsevere disease course (Pancreatology 2011;11:464-8).
"These are patients you can keep on the general medicine ward or perhaps even on observation status," according to Dr. McNally.
The BISAP (Bedside Index for Severity in Acute Pancreatitis) awards 1 point each for the presence of five possible findings: a urea nitrogen level in excess of 25 mg/dL, indicative of third spacing; impaired mental status defined by a Glasgow Coma Score of even a single point less than the normal 15; age over 60; pleural effusion; and the presence of systemic inflammatory response syndrome, or SIRS.
Sixty percent of patients with acute pancreatitis have SIRS on admission. It resolves within 24 hours in half of cases. Persistent or worsening SIRS is associated with an 11%-25% mortality rate. SIRS is defined by two or more of the following: tachycardia, tachypnea, hypocarbia, fever, and either an elevated or depressed white blood cell count.
A patient with a BISAP score of 1 has less than a 2% risk of mortality. In contrast, a BISAP score of 3 is associated with a 22% mortality rate (Am. J. Gastroenterol. 2009;104:966-71).
"If you’re in Hays, Kan., or Rifle, Colo., and you’re seeing a patient at time zero who already has a BISAP of 3, you probably ought to raise the white flag and ship that patient because you’re going to have a lot of problems otherwise," the gastroenterologist advised.
When the diagnosis of acute pancreatitis is uncertain or the triage tools indicate severe disease, the single best imaging modality for looking at the pancreas is CT using what is known among radiologists as the Balthazar pancreatic protocol. It is utilized to assess pancreatic necrosis, the extent of which predicts mortality. There’s no need for CT in a SIRS-negative patient with mild acute pancreatitis.