Objectives: The suspicion of IBD in patients presenting with nonspecific abdominal pain and diarrhea results in the extensive use of invasive diagnostic testing in patients likely to have a functional GI disorder. Noninvasive serodiagnostic tests, however, accurately identify IBD and may serve as effective screening tools. The objective of this study was to examine the cost-effectiveness of initial serodiagnostic screening followed by standard invasive testing, compared to standard invasive testing alone, in patients presenting with uninvestigated symptoms suggestive of IBD.
Methods: Decision analysis was performed to compare the costs and outcomes of competing diagnostic strategies. Probability estimates were derived from the medical literature and expert opinion. Costs estimates were obtained from the Medicare Fee schedule and the cost-analysis was done from a third party payer perspective. The target population was patients with uninvestigated symptoms suggestive of IBD. The outcome measure was cost per correct diagnosis in competing strategies and was assessed at 1 yr.
Results: In the base case analysis, the serodiagnostic strategies were dominant; they were less costly and more accurate than the standard invasive strategies. Sequential serodiagnostic strategies resulted in the largest cost savings ($550 per average patient) with an average cost per correct diagnosis of $1640 compared to $2188 for standard invasive testing. Cost savings were attributable to a 39% reduction in the use of invasive tests. The results were robust to varying model estimates over prespecified ranges in the sensitivity analyses. When costs of invasive testing are reduced by 80% or the prevalence of IBD is at least 83%, serodiagnostic strategies are no longer the most cost-effective.
Conclusions: Initial serodiagnostic screening strategies may represent a cost-effective alternative to standard invasive diagnostic strategies. The economic benefits seem to be achieved by avoiding invasive evaluations in patients without IBD. Confirmation of these findings in a prospective comparative trial seems to be warranted.