Medical and Psychosocial Implications of Adolescent Extreme Obesity - Acceptance and Effects of Structured Care Study, Subproject 4

Obesity is acknowledged as one of the biggest public health challenges today and in the years to come, particularly due to its rising prevalence in children and adolescents. In addition to the physical, mental and social health consequences of the obesity epidemic, a major concern that emanates from overweight and obesity is the related economic burden. Here, the investigators will invexamine the impact of extreme obesity (BMI ≥35kg/m2) on healthcare utilization, costs, and health related quality of life in a cohort of adolescents. Adolescents with more moderate obesity (BMI 30-34.9kg/m2) will serve as a control group. The study is a subproject of the "Medical and psychosocial implications of adolescent extreme obesity - acceptance and effects of structured care", short: "Youth with Extreme obesity Study (YES)", which comprises the recruitment and characterization of obese (BMI 30-34.9kg/m2) and extremely obese (BMI ≥35kg/m2) youth from different healthcare- and non healthcare settings, a randomized controlled trial to investigate a novel intervention targeted at improving quality of life and social functioning of extremely obese adolescents, a structured prospective evaluation of adolescent bariatric surgery, and a long-term prospective observation study.

Based on the current state of knowledge, the investigators have formulated the following hypotheses in regards to healthcare utilization, costs, and health related quality of life:

1. Cost induced by utilization of healthcare services of adolescents with extreme obesity (BMI ≥ 35kg/m2) will be significantly higher compared to cost induced by adolescents with obese (BMI 30-34.9kg/m2). In adolescents who undergo bariatric surgery, cost will decrease after the intervention.
2. Adolescents with extreme obesity (BMI ≥ 35) have significantly lower health related quality of life compared to adolescents with obesity (BMI 30-34.9kg/m2). After specific interventions (psycho-social intervention in subproject 2, bariatric surgery in subproject 3), health related quality of life will increase after the intervention.
3. The cost of the surgical intervention will be accompanied by strong positive effects (such as relative weight loss and health related quality of life) Therefore bariatric surgery will be cost-effective.
4. The high costs of bariatric surgery will be amortized by health savings due to decreased utilization of health care services and lower indirect costs in the medium to long term.

A total of 600 adolescents age 14 to 24.9 years (initially up to 21 years) with extreme obesity (BMI ≥ 35 kg/m2) and 600 adolescents with obesity (BMI 30-34.9 kg/m2) will be recruited over a 24 months period. The five participating university centers are distributed across 4 geographic regions in the North (Berlin), in the West (Essen/Datteln), in the East (Leipzig) and in the South (Ulm) of Germany, and will therefore render data that are representative of Germany as a whole.

Utilization and healthcare costs associated with extreme obesity in adolescents will be assessed via standardized patient questionnaires. Health related quality of life associated with extreme obesity in adolescents will be assessed with validated instruments at baseline and then every 12 months (initially every 6 months). Cost-effectiveness and cost-utility analyses will be performed.