Evaluation of medical and health economic effectiveness of bariatric surgery (obesity surgery) versus conservative strategies in adult patients with morbid obesity.

Background: Obesity with its associated medical, psychological, social, and economic complications is considered a chronic, multifactorial disorder. Given the magnitude of the challenge obesity, there is a clear need for preventive as well as therapeutic measures and strategies on an individual and a public health level.

Objectives: The goal of this health technology assessment (HTA)-report is to summarise the current literature on bariatric surgery, to evaluate their medical effectiveness/efficacy and cost-effectiveness as well as the ethical, social and legal implications of these procedures in comparison to conventional therapies and compared to each other.

Methods: Relevant publications are identified by means of a structured search of databases accessed on 13.11.2006 and an update conducted on 12.11.2007. In addition, a manual search of identified reference lists is conducted. The present report includes German and English literature published since 2001 and targeting adult subjects with morbid obesity (body mass index (BMI) >=40 kg/m² or BMI >=35 kg/m² with severe comorbidities). The methodological quality of studies included is assessed according to pre-defined quality criteria by two independent scientists.

Results: Among 5910 retrieved publications, 25 medical articles, as well as seven health economic studies meet the inclusion criteria. The medical studies show a superior weight loss following bariatric surgery compared to conventional therapy. Malabsorptive procedures lead to a more profound weight loss than purely restrictive procedures. Weight reduction in general is accompanied by a reduced frequency of comorbidities (mostly diabetes type 2). The evidence is not sufficient to quantify these effects for individual procedures or to assess long-term outcomes. However, recent studies show a profound survival benefit for surgically treated patients up to a period of eleven years. The economic studies illustrate that bariatric surgery is cost-effective compared to no treatment or conservative treatment. The comparison between surgical therapies does not allow to draw any conclusions on cost-effectiveness. Appropriate studies/surveys, which are concerned with ethical, legal and social aspects, are not available.

Discussion: Concerning clinical outcomes as well as cost-effectiveness, there is a lack of high quality studies. Clinical effectiveness and safety as well as cost-effectiveness of bariatric procedures in the short- and medium-term course are agreed on, but long-term evaluations that focus not exclusively on weight loss, but also on comorbidities and patient relevant outcomes such as quality of life, are needed. Also within the economic views are missing long-term evaluation particularly for the German health care system.

Conclusion: Based upon the available literature the short- and medium-term effectiveness of bariatric procedures on weight loss, comorbidities, e. g. diabetes, and mortality can be assumed and also seems to be cost-effective. No recommendation can be given with respect to the choice of a certain bariatric procedure or to the selection of particular groups of patients.