Cost-effectiveness analysis of subtraction scintigraphy in patients with acute lower gastrointestinal tract hemorrhage.

UNLABELLED (99m)Tc-labeled red blood cell scintigraphy is a powerful detection and localization tool that may be confounded by false-positive and false-negative findings. Subtraction scintigraphy has been used in the evaluation of acute lower gastrointestinal tract hemorrhage (LGIH) to reduce the impact of interpretive confounders. The aim of this investigation was to evaluate the cost-effectiveness of the addition of subtraction scintigraphy in the evaluation of patients with acute LGIH. METHODS The clinical phase of this research was a retrospective clinical study with a repeated-measures design including randomized control and experimental groups. A total of 49 patient studies were included in the sample. Studies were randomized and interpreted by 4 independent physicians. Decision-tree analysis was used to model direct costs and the potential risks of procedures for 2 diagnostic strategies for patients with acute LGIH: conventional scintigraphy alone and conventional scintigraphy combined with subtraction scintigraphy. The transition probabilities (or branching fraction at each decision node) for scintigraphy were based on the clinical results of this investigation. All other transition probabilities were derived from previously cited data. RESULTS Combining subtraction techniques with conventional scintigraphy reduced the overall costs of procedures for patients with acute LGIH by $74 per patient and reduced deaths by 17.6% and complications by 15.7%. For conventional scintigraphy alone, 8.8% of patients presenting for scintigraphic evaluation of acute LGIH would undergo unnecessary angiograms, and 2.8% would have unnecessary surgery. These figures were reduced to just 5.4% and 1.8%, respectively, with the addition of subtraction scintigraphy. CONCLUSION The use of subtraction scintigraphy as an adjunct to conventional scintigraphy for patients with acute LGIH may provide both cost and outcome benefits.