After the completion of the evaluation of bariatric surgery candidates, when all of the results of patient interviews, specialty consultations, and diagnostic studies are available, the important decisions necessary for patient selection and treatment planning must take place. The detailed findings and recommendations from the surgeon and the bariatric team are shared with the patient at the Summary Interview referred to in Chap. 4. To review some of the issues raised in Chap. 4, informed consent is not simply the patient signature on the consent form, it occurs during the entire process of dialogue between the patient, the surgeon, and the bariatric surgery team members. This dialogue, the components of which take place throughout the evaluation process, should assure that the patient understands the reasons for the treatment recommendations, its risks and benefits, and the available alternate courses of action. All questions must be answered and the patient should agree that the treatment should take place. The underlying principle of informed consent is a shared decision-making partnership between the patient and the surgeon resulting in patient-centered decisions [1].

An essential component of the patient selection and informed consent process involves a careful comparison of risk versus benefit of bariatric surgery. The ability to identify and perhaps quantitate with metrics those patient factors that influence surgical risk, and those that influence weight loss and health success will improve patient and procedure selection as well as surgical outcomes and the overall value of bariatric surgery. Additional benefits of measurement of these factors will allow for a more individualized and patient-centered informed consent process with the presentation of adequate information, and the implementation of strategies to reduce risk when indicated.

Bariatric surgeons have made great progress during the last 5 years in the identification of patient factors that increase surgical risk. The recent studies contributing to risk measurement are summarized in Table 12.1. These studies analyze the data from bariatric surgery databases ranging from single or multicenter center experience, from administrative databases, and from clinical registries [2–13]. In each study, the rate of adverse events or mortality is determined as the primary endpoint. Multiple patient factors are then analyzed by univariate analysis to determine their association with the major endpoint. Those variables that are statistically significant according to a predetermined threshold are then individually considered for inclusion in a multiple logistic regression model designed to identify independent predictors of the major endpoint. The variables are selected using a manual forward stepwise approach after consideration of supporting literature, the statistical strength of the univariate association, correlation with other variables already in the model, and the frequency of occurrence. The patient-level risk factors identified in each study are listed together with odds ratios, which measure the strength of the association (Table 12.1).

These studies provide information that allows bariatric programs to develop metrics for determination of the specific risk for individual patients, either in the form of a risk score to identify risk classes (i.e., low, medium, or high), [3, 7, 8, 12, 13] or by using calculators to estimate the probability of an adverse event [9, 10]. Many of the risk assessment tools developed thus far have proven efficacy as they have been validated in independent patient populations [3, 8–10, 12, 14, 15].