Modeling lengthy work-ups in gastrointestinal bleeding.

Multiple procedures and medical devices are being used in a complex interplay to diagnose and treat gastrointestinal bleeding. The aim of the study was to develop a mathematical model that helps in estimating the average number of procedures to be expected in the general management of gastrointestinal bleeding. The modeling process serves as an example of how mathematical analysis in general can be used to answer unresolved clinical questions, lead to a better understanding of the underlying influences in a disease process, and provide a starting point for future clinical trials. The analysis uses a Markov chain to model the transition probabilities among consecutive interventions used to find and treat a bleeding site. The results show that starting a work-up of gastrointestinal bleeding with an esophagogastroduodenoscopy will lead on average to 2.69 procedures per patient. Of these expected procedures, 1.46 will be esophagogastroduodenoscopies, 0.69 colonoscopies, 0.25 video capsule endoscopies, 0.14 double-balloon enteroscopies, and 0.14 procedures from interventional radiology. Management chains initiated with a colonoscopy result in similar outcomes. Among 10,000 simulated individual patients, the number of procedures varies between 1 and 16 consecutive procedures, with 95% of all patients undergoing 6 procedures or less. The outcomes of the model suggest that the published success rates of endoscopic and radiographic procedures are overly optimistic. The results also point to the need to generate clinical data through future studies that more reliably account for treatment failures and the interchange among various complementary diagnostic modalities.