Occult OGIB remains a diagnostic challenge. New technologies such as CE and DBE allow examination of the entire small bowel. It is unclear how these new diagnostic and therapeutic strategies should be incorporated into our current armamentarium. This cost-minimization analysis suggests that the optimal strategy to manage patients with occult OGIB depends on whether endoscopic or surgical intervention is required versus visual diagnosis of lesions. For patients in whom endoscopic or surgical intervention is necessary, a strategy that employs DBE as the initial test may be optimal. However, if only visual diagnosis of a lesion is necessary, a strategy employing initial CE is preferred. Additionally, it is recognized that capacity for performance of DBE in most practice settings is insufficient to allow it to be conducted in every patient with OGIB. In this case, CE appears to be the optimal initial test.
Despite the increased interest in CE and DBE in the evaluation of OGIB, few studies address the optimal initial testing strategy. Lewis and Goldfarb argued for initial CE evaluation of OGIB based upon clinical reasoning and lower medical costs.5
A recent meta-analysis found that CE offered a superior diagnostic yield when compared to PE, SBFT, and EN;27, 28
however, neither study provided comparison with DBE. To date, there are few comparative studies between CE and DBE. One study of 35 patients reported superior performance with CE while a case series of four subjects described missed lesions with CE subsequently found on DBE.19, 29
Several articles have noted the need for an economic analysis of CE and DBE in the evaluation of OGIB.29–31
This cost-minimization analysis illustrates that either CE or DBE may constitute economically sound initial testing strategies. The preferred initial test depends upon the patient presentation and whether endoscopic or surgical therapy is required. Most likely these are complementary procedures for use in this patient population.
A major limitation of this analysis stems from the type of data available in published literature. Although IOE and DBE may be considered gold standards, both tests have not been routinely applied to all subjects in published case series. Therefore, the data are fragmented with individual test characteristics and few studies employ simultaneous testing strategies. Studies that compared multiple diagnostic tests were preferentially used for inputs in the base-case scenarios. The diagnostic yield of various strategies in the literature is partly confounded by the indication for that testing strategy. That is, there is inherently greater yield associated with tests such as DBE given that subjects referred for such studies often have been refractory to conventional therapy. In contrast, the diagnostic yield of CE may be biased towards lower performance since the pretest probability of disease is typically lower than among subjects referred for DBE. Furthermore, it should be noted that the distribution of lesion type is dependent upon the patient demographics. It is known that patients with renal failure will have more vascular ectasias as their source of OGIB.32, 33
Several studies have also suggested that the diagnostic yield is dependent on timing of the diagnostic test such that administration of a diagnostic test early in the course of disease offered higher yield than delayed testing.34
Our model assumed a static lesion that was unaffected by the order of testing. Because of these shortcomings in the literature, we used sensitivity analyses to test a wide range of inputs.
Our cost-analysis was limited to a third-party payer perspective, although there are additional relevant perspectives. For example, the cost to the endoscopist and their capacity to deliver care was not evaluated. In the case of DBE, incomplete upper DBE examinations warrant performing the retrograde procedure another day; it is not uncommon that the antegrade procedure takes 90 minutes while the retrograde procedure is an additional 70 minutes.15, 21, 22
The willingness of endoscopists to provide DBE will likely depend on reimbursement; if greater revenue can be generated per unit time from performance of other procedures it is unlikely that DBE capacity will meet demand. Specifically, if current reimbursement for DBE remains at $875, the amount reimbursed by CMS for small bowel enteroscopy, it is unlikely that DBE will gain wide adoption into clinical practice.
Future studies should include concomitant testing of patients with CE and DBE, which will allow better understanding of the diagnostic yields of these new tests. Additionally, the national capacity for DBE has not been evaluated. Because of the initial capital investment, the steep learning curve associated with the procedure, and issues related to provider reimbursement relative to time consumption of the procedure, DBE may not be widely available in clinical gastroenterology practice. Beyond the direct health care costs, opportunity costs incurred by the gastroenterologist as well as potential costs to patients required to endure longer waits in the queue should be identified in order to provide more accurate overall health care costs.
In conclusion, a strategy using initial DBE to evaluate occult OGIB after negative endoscopy and ileocolonoscopy appears to be least costly if the goal of testing is treatment or definitive diagnosis. However, initial CE is preferred if the capacity of DBE is insufficient to meet demand or if the cost of either antegrade or retrograde DBE exceeds $1,849 or if the sensitivity of DBE is less than 68%. Alternatively, if the goal is limited to visual identification, initial CE may be preferred. Given the current reimbursement for DBE relative to its prolonged procedure time, the fixed cost of capital investment, and the technical skill required to perform the procedure, DBE capacity will likely remain low. It is therefore likely that CE will be viewed as a viable initial test in the evaluation of OGIB.