Purpose: To compare the cost-effectiveness of different imaging strategies in the diagnosis of pediatric appendicitis by us�ing a decision analytic model.
Materials and methods: Approval for this retrospective study based on literature review was not required by the institutional Research Eth�ics Hoard. A Markov decision model was constructed by using costs, utilities, and probabilities from the literature. The risk of radiation-induced cancer was modeled by using the Biological Effects of Ionizing Radiation VII report, which is based primarily on data from atomic bomb survi�vors. The three imaging strategies were ultrasonography (US), computed tomography (CT), and US followed by CT if the initial US study was negative. The model simulated the short-term and long-term outcomes of the patients, calculating the average quality-adjusted life span and health care costs.
Results: For a single abdominal CT study in a 5-year-old child, the lifetime risk of radiation-induced cancer would be 26.1 per 100 000 in female and 20.4 per 100 000 in male patients. In the base-case analysis, US followed by CT was the most costly and most effective strategy, CT was the second-most costly and second-most effective strategy, and US was the least costly and least effective strategy. The incremental cost-effectiveness ratios (ICERs) of CT to US and of US followed by CT to US were both well below the societal willingness-to-pay threshold of $50 000 (in U.S. dollars). The ICER of US followed by CT to CT was less than $10 000 in both male and female patients.
Conclusion: In a Markov-based decision model of pediatric appendici�tis, the most cost-effective method of imaging pediatric appendicitis was to start with a US study and follow each negative US study with a CT examination