TEXT
Acute pancreatitis is an acute inflammatory process of the pancreatic gland. According to the Atlanta classification system, there are two forms of acute pancreatitis: mild acute pancreatitis, characterized by interstitial edema, which is self-limiting and severe acute pancreatitis characterized by local complications such as necrosis, abscesses, pseudocysts and the presence of organ dysfunction [1]. The mortality due to severe pancreatitis is about 25%-50% and is due mainly to infection of the necrosis[2]. Early identification of patients with severe acute pancreatitis is essential for the correct care of the disease and the avoidance of complications.
Over the past 20 years, many schemes have been proposed for identifying severe pancreatitis. The aim of this paper is to review the current criteria for the early assessment of severity of acute pancreatitis.
CLINICAL CRITERIA
Bank et al[3] analyzed the incidence of cardiac, pulmonary, kidney, hematological, metabolic and neurological complications in 75 patients with acute pancreatitis and they reported a mortality rate of 56% if one or more complications were present. Subsequently, Agarwall and Pitchumoni[4]conducted a retrospective study involving 76 patients and proposed a scheme comprised of simplified clinical criteria. In both studies, a 48-hour observation period was necessary for the clinical criteria. Furthermore, these clinical assessments depend on the experience of the clinical team and are difficult to standardize.
CLINICAL AND LABORATORY CRITERIA
Ranson et al[5] identified a series of 11 criteria evaluated in 100 patients with acute pancreatitis in 1974. The Ranson score is still widely used at present in judging severity. Five of the 11 criteria are considered upon hospital admission and 6 in the following 48 h. They reported that most patients with less than two positive items survived; in those with 3 or 5 positive items, the mortality rate was about 20%, and in those with 6 or more positive items, the mortality reached about 50%. There is a correlation between 3 or more Ranson positive criteria and the high incidence of pancreatic necrosis and systemic complications. Later studies confirmed a sensitivity from 40% to 90%[4,6]. The Ranson score has been recently criticized for the following reasons: a good assessment of severity requires the determination of all items and requires 48 h of observation for the judgement of severity, thus delaying the proper treatment after the onset of pain. Talamini et al[7] have simplified the original Ranson score by evaluating only the items considered on admission and concluded that this simplified system is of little use for predicting severity. Finally, this criteria correlate to the severity of acute pancreatitis only at the opposite ends of the scheme (< 2 and > 6 items) but not between 3 and 5 positive items. Twelve to 24 h after the onset of pain, the score is completely useless. It can be applied only to biliary pancreatitis and the same authors have therefore proposed a new modified score[8].
Imrie et al[9] have proposed a score called the Glasgow score which seems to be more precise than that of Ranson, with a sensibility for the assessment of severe acute pancreatitis of 56%-85%[10,11].
Another simplified score has been set up by Fan et al[12], utilizing only two biochemical parameters (azotemia and glycemia). This score system has a sensitivity of about 75% in the assessment of the severity of acute pancreatitis.
More recently the APACHE II score[13] which takes into consideration age, presence of chronic associated diseases and some biochemical parameters has been proposed for the assessment of the severity of acute pancreatitis. Wilson et al[14] have reported a score of 6.3 in patients with mild acute pancreatitis, of 9.4 in those with severe pancreatitis and of 14.1 in those with fulminant pancreatitis.
BIOCHEMICAL CRITERIA
The search for a marker able to evaluate the severity of acute pancreatitis at the early stage is the aim of the present research in the field of pancreatology. The evaluation of the severity of acute pancreatitis by means of serum pancreatic enzyme determination has been a boon[15-17]. We recently evaluated serum amylase and lipase in 66 patients with acute pancreatitis[15]. Most of these patients were studied within 24 h from the onset of pain. Twenty patients had no alterations of the pancreatic gland at imaging, 36 had pancreatic edema and 10, pancreatic necrosis. The elevation of the serum pancreatic enzyme s overlapped in the three groups.
The determination of serum C-reactive protein[18] is at present widely used for the assessment of the severity of acute pancreatitis. Serum levels of t his protein greater than 100 mg/L indicate a severe acute pancreatitis in about 60%-80% of the cases. The determination of the C-reactive protein is easy to perform and inexpensive. However, its sensitivity is good only after the first 48 h from the onset of pain[6,19].
Granulocyte elastase has been evaluated in the search for biochemical markers able to evaluate the severity of acute pancreatitis even earlier than the C-reactive protein determination. This protein is released by activated neutrophils and it is able to damage cellular membranes and the extracellular matrix. Gross et al[20] and Dominguez-Munoz et al[21] have reported that 70%-80% of the patients with severe acute pancreatitis studied within 48 h from the onset of the pain were correctly identified using this protein. More recently interleukin 6, released by activated macrophages and the interleukin 8 released by neutrophils have been proposed as markers of the severity of acute pancreatitis. These two cytokines are released rapidly in severe forms of acute pancreatitis (within 24 h from the onset of pain) and have a specificity greater than that of C reactive protein (80%-100%)[22-24].
The soluble receptor of interleukin 2, which is released by the activated lymphocytes is able to identify 70% of the patients with severe acute pancreatitis studied within 24 h from the onset of pain[25]. We have demonstrated[26] that the human pancreatic secretory trypsin inhibitor, produced by the pancreatic acinar cells and the hepatocytes is able to correctly identify 70% of the cases studied within 24 h from the onset of pain. All these studies demonstrate that the immune system is early activated at an early phase during the course of acute pancreatitis. However, the determination of these proteins, except for C-reactive protein and granulocyte elastase, is not feasible for routine use. We hope that in the near future simple techniques for the determination of these proteins will be developed.
RADIOLOGICAL CRITERIA
Balthazar et al[27] have demonstrated that contrast enhanced computed tomography is able to assess the severity of acute pancreatitis. They divided the severity of acute pancreatitis into 5 categories. In 83 patients with acute pancreatitis, they found that the mortality was nil in stages A, B and C, and re ached 17% in those of grade E. The findings of left-sided or bilateral effusion s on chest radiograph within 24 h of admission were associated with a severe outcome[28].
RADIOLOGICAL AND BIOCHEMICAL CRITERIA
Serum creatinine greater than 152.6 μmol/L and/or the presence of pathological chest radiographs (pulmonary densification and/or pleural effusions) are capable of identifying, within 24 h of admission t o the hospital, subgroups of both patients at higher risk of adverse clinical outcome and of patients with necrotizing pancreatitis[29].
CONCLUSION
In conclusion, the Ranson, Glasgow and Fan criteria are at present useful in clinical practice for their simplicity and low costs. The APACHE II score gives useful information in patients with a more severe form of acute pancreatitis. Serum determination of interleukins may play a role in the assessment of the severity of acute pancreatitis only when rapid techniques for their determination are developed. At present, C-reactive protein is the marker which is the easiest to perform and which has the lowest cost. The evaluation of both chest radiographs and serum creatinine is also simple to carry out in the Emergency Room.
