A cost analysis of long term antibiotic prophylaxis for spontaneous bacterial peritonitis in cirrhosis

The aim of this study was to perform a cost analysis of different strategies of long term antibiotic prophylaxis for spontaneous bacterial peritonitis (SBP) in patients with cirrhosis and ascites. The study involved a cost analysis using a decision analysis model and patients with cirrhosis and ascites who are at risk for developing SBP.

Two different strategies of antibiotic prophylaxis were compared with a "no prophylaxis" strategy in patients with cirrhosis and ascites using a decision analysis model. In strategy I, antibiotic prophylaxis was administered in all patients with cirrhosis and ascites and in strategy II, patients were stratified into a low risk and a high risk group on the basis of serum bilirubin and ascitic fluid protein levels; only patients in the high risk group received antibiotic prophylaxis. The cost per patient treated for 1 yr was the outcome measure compared in the different strategies. Clinical input probabilities and ranges used were obtained by searching the MEDLINE database for English language articles. Cost estimates were obtained from a university hospital setting. Cost analysis was done with a societal perspective, and only direct costs were taken into account. Sensitivity analyses were performed to evaluate the effect of variations in the key clinical probabilities and cost estimates ranging from a best case to a worst case scenario on the outcome measure.

The estimated cost per patient treated in strategy I, strategy II, and strategy III (the strategy of "no prophylaxis") were $1311, $1123, and $3509, respectively. Over a broad range of clinical and cost variables, the strategy of risk stratification and restriction of antibiotic prophylaxis to the subgroup of patients with cirrhosis and ascites who were at high risk for SBP (as identified by serum bilirubin >2.5 mg/dl and ascitic fluid protein <1 g/dl) was the most favored strategy. However, when the cost of prophylaxis was low or the probability of a primary episode of SBP was at the lower end of the range reported in the literature, administering antibiotic prophylaxis to all patients with cirrhosis and ascites was the least costly strategy.

This cost analysis indicates that antibiotic prophylaxis particularly when restricted to a subgroup of patients who, by simple laboratory parameters, are identified to be at high risk for SBP, is very cost-effective in the prevention of SBP in patients with cirrhosis and ascites.