title: Competing influences in the management of gastrointestinal bleeding.
abstract: OBJECTIVE
  Management of gastrointestinal (GI) bleeding centers on the issues of location, type of mucosal lesion, effects of anticoagulation, diagnosis, and therapy. Each one of these five individual factors is affected by multiple interactions with the other coexisting factors. The aim of the present study is to analyze which set of factors ultimately exerts the largest and most lasting influence on the disease process.
  
  
  METHODS
  The interactions among the five contributing factors are analyzed using a transposed Markov chain model.
  
  
  RESULTS
  The analysis reveals that, in declining order, location, anticoagulation, and type of lesion exert the largest influence on the disease process. Under steady state conditions, their magnitudes of influence are 50, 33, and 17%, respectively. The other two factors, diagnosis and therapy, result as a consequence of the aforementioned three primary factors, but do not exert any major influence themselves. The outcome of the analysis remains robust to multiple wide-ranging variations in the assumptions underlying the model.
  
  
  CONCLUSIONS
  The model of a transposed Markov chain translates an initially bewildering array of interacting influences into a coherent and transparent model of gastrointestinal bleeding.
authors.affiliation: Department of Gastroenterology, Portland VA Medical Center and Oregon Health and Science University, Portland, Oregon, USA.
authors.forename: Amnon
authors.initials: A
authors.lastname: Sonnenberg