Patient-centered outcomes research in bariatric and body contouring surgery

The first chapters of this thesis provided a comprehensive approach for the standardization of patient-reported outcome measures (PROMs) in bariatric and body contouring surgery. Chapter 2 provides validation evidence about the most appropriate PROM for use in bariatric and body contouring surgery. This systematic review showed that the majority of the PROMs used in bariatric and body contouring surgery have not been thoroughly validated to assess quality of life in bariatric surgery and body contouring patients. The Standardizing Quality of Life measurement in Obesity Treatment (S.Q.O.T.) initiative is an international effort to standardize patient-reported outcome (PRO) measurement in obesity treatment to improve meaning of outcome evaluation in obesity treatment. Chapter 3 reported the results of the first international multidisciplinary S.Q.O.T. meeting including people living with obesity, which aimed to achieve consensus on the key PROs that should be measured in research studies on obesity treatment, and a first selection of the PROMs to capture this information. The following chapters of this thesis provided a comprehensive approach for the development and/or validation of scientifically sound PROMs in bariatric and body contouring surgery. Chapter 4 described a validation study of the RAND-36 in patients undergoing bariatric surgery. The RAND-36 is the most frequently used, but non-validated PROM in bariatric surgery. The study found that the RAND-36 did not demonstrate evidence of validity and reliability in bariatric surgery patients, which means that this PROM is not appropriate for use in this patient population. Chapter 2 further demonstrated that a PROM, the BODY-Q, possessed the strongest evidence for quality of measurement properties (reliable, valid and adequate for the intended purpose). The BODY-Q is a PROM used around the world to measure outcomes in people living with obesity who undergo weight loss and/or body contouring. The BODY-Q is composed of multiple scales that can be used as stand-alone measurement instruments. This enables to develop new scales and in chapter 5 and 6, we developed and validated additional scales for important obesity-specific constructs that were thus far not included in the BODY-Q. Chapter 5 described the development and validation of a new BODY-Q scale to measure appearance of cellulite, and chapter 6 described the development and validation of 5 new BODY-Q scales measuring expectations, eating behavior, eating-related distress, eating-related symptoms, and work life. Findings from the psychometric analysis indicated that the new scales described in both chapters were both valid and reliable for use in bariatric and body contouring surgery. The original BODY-Q scales were later translated into Dutch and further validated in a study described in chapter 7. Findings from this study supported the application of the BODY-Q in the Netherlands. In chapter 8 international normative values of the BODY-Q were established and calculated by age, gender and BMI classification group. These data could be used as normative comparison values to provide clinical context for both preoperative and postoperative BODY-Q data in bariatric and body contouring surgery, demonstrating the value of bariatric and body contouring surgery. The subsequent chapters of this thesis (chapter 9-14) provided a comprehensive overview of clinically meaningful outcome evaluation in bariatric and body contouring surgery. Following the evidence that the BODY-Q is currently the most appropriate PROM for use in bariatric and body contouring surgery, the BODY-Q was being used as primary endpoints for the evaluation of outcomes after bariatric and/or body contouring surgery. These following studies assessed the consequences of obesity and its treatment specifically and directly from the patient’s perspective using the BODY-Q. The final chapters (chapter 15-17) represented studies and describe methods and results to guide future development of treatment, research, and policy in body contouring surgery