Chapter 12

• Decision analysis is a formal process used to determine the preferred course of action from two or more potential approaches to clinical management.
• Decision analysis is most appropriate when there is both some uncertainty about the preferred course of action and a meaningful trade-off of risks and benefits for the alternative management strategies.
• A decision tree or decision diagram is the underlying structure of the clinical situation, including all uncertainties and choices, as well as all outcomes.
• The expected utility is the estimated typical or average outcome for a population of patients managed with a particular strategy.
• Substituting a range of values for a particular probability in a decision tree and determining the impact on the expected utility is referred to as a sensitivity analysis.

A 50-year-old man presented to his physician with a high fever and severe abdominal pain. This patient occasionally worked as a house painter, and although he reported heavy use of alcohol, he had been in generally good health. There was no history of exposure to toxic substances or intravenous drug use. On physical examination, the patient was jaundiced, and he had severe tenderness to palpation in the right upper quadrant of his abdomen. Laboratory examination revealed leukocytosis accompanied by elevations in the serum levels of bilirubin, alkaline phosphatase, and serum glutamic oxaloacetic transaminase (SGOT, aspartate aminotransferase). It was considered that the patient had either alcoholic hepatitis or cholangitis (inflammation of a bile duct). It is necessary to differentiate cholangitis, which requires surgery, from alcoholic hepatitis, in which surgery is contraindicated. In fact, the postoperative mortality for alcoholic hepatitis is very high. The issue for the medical decision-maker is to choose the alternative that will carry the greatest benefit for the patient with the lowest achievable risk.

Cholangitis, an infection of the biliary ductal system, classically presents with a triad of fever, jaundice, and pain in the right upper quadrant of the abdomen. The clinical illness arises in the presence of bacterial colonization of the bile, most commonly because of obstruction of biliary tract flow. Historically, the most common underlying cause of obstruction was blockage of the biliary tract by stones, although malignant strictures have become increasingly important contributors in recent years. The increased pressure within the bile ducts resulting from obstruction produces bacterial reflux into the hepatic veins and perihepatic lymphatics, with subsequent bacterial spread into the circulating bloodstream. The bacteria associated with cholangitis include Escherichia coli, Klebsiella species, and the enterococci, with a shift more recently to include Enterobacter and Pseudomonas species. Infections typically involve multiple species of organisms.

The clinical manifestations of cholangitis range from asymptomatic illness to severe toxic symptoms, including septic shock. Fever is present in almost all patients, typically accompanied by chills. Jaundice and abdominal pain in the right upper quadrant of the abdomen are part of the classical description of presenting symptoms, although they may not be present in the absence of obstructive stones. Complications of ...

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