[Principles of risk research in surgery: definition, calculation and clinical use in the problem of upper gastrointestinal hemorrhage].

In surgery, risk research is of great importance at the present time but is controversely discussed with contradictory definitions, calculations and applications. In this paper standardized and quantitative definitions of risk and risk factors using probabilities are given. A calculation of risk, risk factors and risk rates is performed using data from studies on bleeding duodenal ulcers. Possible applications of risk and risk factor research (risk analysis) in suitable treatment policies are demonstrated using data from patients with bleeding duodenal ulcers. The utility of this type of approach, using decision tree analysis, clearly manifests itself in the reduction of lethality. Objective and quantitative surgical risk research and its application as risk analysis using probabilities can improve patient care in standard surgical situations.