Risk calculators-methods, development, implementation, and validation.

INTRODUCTION: A surgical risk calculator (SRC) estimates the probabilities of unfavorable outcomes such as complications or death after a specific surgery. The risk estimates are based on information regarding the patient's medical history and his current status. They are calculated using risk models derived from the analysis of data from a large number of previous patients in a similar clinical situation. METHODS: This paper discusses several aspects of the SRC development and its implementation into clinical practice: the development of the statistical risk models, their validation and software implementation, the use of the SRC output for shared decision making in clinical settings, and the evaluation of the SRC's impact on individual patient outcomes as well as on the institution's quality of care of the clinical institution. RESULTS: Probably the most elaborate SRC is the ACS NSQIP SRC. A comparable project was started by the German Society for Visceral and General Surgery (DGAV) in the framework of its Study, Documentation, and Quality Center (StuDoQ). It is relevant to consider that the transportability of a SRC from a US American to a German setting is not straightforward. CONCLUSIONS: Risk calculators are important instruments for shared decision making between patients and doctor. Their implementation into clinical practice has to solve technical issues, and it is related to appropriate training of clinicians. There are specific study designs to evaluate the clinical impact of a SCR.