CT assessment in pancreatitis strongly correlates with patient outcomes [Classics Series]

This study summary is an excerpt from the book 2 Minute Medicine’s The Classics in Medicine: Summaries of Landmark Trials

1. In patients with acute pancreatitis, the presence and degree of pancreatic necrosis was correlated with mean length of hospital stay, complications and mortality.

2. By combining an existing acute pancreatitis grading system with computed tomography (CT) assessment of pancreatic necrosis, the authors generated a CT severity index that was strongly correlated with patient outcomes.

Original publication date: February 1990

Summary of the study: Acute pancreatitis is a common condition involving inflammation of the pancreas. Although most patients have a mild course without associated complications, some develop severe disease associated with high rates of morbidity and mortality. Many attempts have been made to estimate patient prognosis in acute pancreatitis, including attempts to correlate imaging findings with patient outcomes using computed tomography. However, due to the limitations of early CT technology, pancreatitis grading scales suffered from poor sensitivity and specificity and were not widely used. In this trial, the study authors attempted to build on this previous work by using contrast-enhanced computed tomography to assess the presence and degree of pancreatic necrosis as a prognostic indicator for acute pancreatitis. Using a prospective cohort of patients at a single institution, the study authors demonstrated a strong and positive relationship between pancreatic necrosis and patient outcomes. Compared with those who had a normal-appearing pancreas on CT, patients with necrosis had significantly longer hospital stays and higher rates of complications. All deaths in the study cohort were in patients with pancreatic necrosis. By combining this information with the rating scales described previously, the authors were then able to generate the CT Severity Index (CTIS), a numerical scale to predict the risk of complications and death. Applying this scale to the study cohort, morbidity and mortality were strongly correlated with the CTIS score. The main limitations of this study included the modest sample size and associated low mortality rate. Later work on pancreatitis imaging extended to this landmark trial, the results of which remain in modern clinical practice as modified CTIS.

Click to read the study in Radiology

In depth [randomized control trial]: Eighty-eight patients (mean age, 52 years) with signs and symptoms of acute pancreatitis were included. All patients were initially managed with standard medical therapy, including nasogastric suction, analgesia, and intravenous fluids. Surgical intervention was continued in patients with sepsis refractory to medical management. All patients underwent CT imaging of the abdomen with intravenous and oral contrast for assessment of pancreatic necrosis at admission, and a subset of patients received subsequent additional CT imaging (mean number of CT/patients, 2.9). The scans were blindly interpreted and assessed for two specific characteristics: the patient’s five-point grade of pancreatitis, based on previously published data; and the qualitative degree of decrease in pancreatic parenchyma enhancement. This latter variable was taken to represent the presence of pancreatic necrosis and was reported as one of four possible severities. Additional data collected included Ranson score, length of hospital stay, morbidity – defined as pancreatic abscess or pseudocyst formation – and mortality. At the end of the trial, 66 patients (75.0%) had uncomplicated outcomes and recovered with medical treatment alone, while 22 patients (25.0%) required surgery. Five (5.7%) patients died. In total, pancreatic necrosis was detected in 18 (20.5%) patients. The mean length of stay was 109 days in patients with > 50% necrosis, versus 25 days in those with no evidence of necrosis at presentation. The mean Ranson score (a marker of severity, maximum score 11) was 1.9 in those without necrosis and 5.5 in those with > 50% necrosis. Patients with CT signs of necrosis had morbidity and mortality rates of 82% and 23%, respectively, compared to rates of 6% and 0%, respectively, in those without necrosis. The positive predictive value of abscess formation was 77% in patients with necrosis, and the negative predictive value of abscess formation in those without necrosis was 97%. By combining the grade of pancreatitis and the CT extent of pancreatic necrosis, a CT severity index was created with a maximum score of 10 (highest severity). Among study patients with CTSI 0-3, there was 3% mortality and 8% morbidity; among patients with CTSI 7-10, mortality and morbidity were 17% and 92%, respectively.

Balthazar EJ, Robinson DL, Megibow AJ, Ranson JH. Acute pancreatitis: interest of CT in establishing the prognosis. Radiology. 1990 Feb 1;174(2):331–6.

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