DECISION-ANALYSIS TO ASSESS COST-EFFECTIVENESS OF LOW-OSMOLALITY CONTRAST-MEDIUM FOR INTRAVENOUS UROGRAPHY

Decision analysis was used to compare the cost-effectiveness of a conventional ionic high-osmolality contrast medium with that of a nonionic low-osmolality contrast medium when used for i.v. urography. The patient populations considered in the model were those with a low risk and those with a high risk of contrast medium-associated adverse effects. Mean toxicity rates for the contrast media were obtained from the literature. To estimate the average cost of adverse effects, the probability of a patient in each population developing a mild, moderate, or severe reaction was multiplied by the respective estimated cost for each level of severity, and the products were summed. The incremental cost of the low-osmolality medium per case of adverse effects prevented was calculated by dividing the difference between the average costs of the two media by the difference between the frequencies of toxicity associated with the agents. According to the 1990 cost data used, combined mean drug and toxicity costs were $68 and $13 for the low- and high-osmolality contrast media, respectively, per high-risk patient and $67 and $10 per low-risk patient. The incremental costs of the low-osmolality medium per case of severe adverse effects prevented was $17,974 in the high-risk population and $77,027 in the low-risk population. Sensitivity analysis showed the results to be stable over a range of data used in the model. Decision analysis suggested that a low-osmolality contrast medium, when being considered for use in i.v. urography, should be used only for high-risk patients and that the marginal costs for universal use would be unacceptably higher than the marginal benefits.