title: Modeling the impact of adjustable gastric banding on survival in patients with morbid obesity.
abstract: OBJECTIVE
  Morbid obesity is associated with premature death. Adjustable gastric banding may lead to substantial weight loss in patients with morbid obesity. Little is known about the impact of weight loss on survival after adjustable gastric banding. We therefore developed a mathematical model to estimate life expectancy in patients with a body mass index (BMI) > or =40 kg/m(2) undergoing bariatric surgery.
  
  
  METHODS
  We developed a nonhomogeneous Markov chain consisting of five states: the absorbing state ("dead") and the four recurrent states BMI > or =40 kg/m(2), BMI 36 to 39 kg/m(2), BMI 32 to 35 kg/m(2), and BMI 25 to 31 kg/m(2). Scenarios of weight loss and age- and sex-dependent risk of death, as well as BMI-dependent excess mortality were extracted from life tables and published literature. All patients entered the model through the state of BMI > or =40 kg/m(2).
  
  
  RESULTS
  In men aged either 18 or 65 years at the time of surgery, who moved from the state BMI > or =40 kg/m(2) to the next lower state of BMI 36 to 39 kg/m(2), life expectancy increased by 3 and 0.7 years, respectively. In women aged either 18 or 65 years at the time of surgery, who moved from the state BMI > or =40 kg/m(2) to the next lower state BMI 36 to 39 kg/m(2), life expectancy increased by 4.5 and 2.6 years, respectively. Weight loss to lower BMI strata resulted in further gains of life expectancy in both men and women.
  
  
  CONCLUSIONS
  Within the limitations of the modeling study, adjustable gastric banding in patients with morbid obesity may substantially increase life expectancy.
authors.affiliation: Medical Informatics and Technology Assessment Research Group, Baar, Switzerland. psendi@swissonline.ch
authors.forename: Pedram
authors.initials: P
authors.lastname: Sendi
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Palmer
authors.forename: Philipp
authors.initials: P
authors.lastname: Hauri
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Craig
authors.forename: Fritz F
authors.initials: FF
authors.lastname: Horber
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D005260:Female; D015391:Gastroplasty / Q000379:methods; D006801:Humans; D008017:Life Expectancy; D008297:Male; D008390:Markov Chains; D008875:Middle Aged; D009767:Obesity, Morbid / Q000401:mortality* / Q000601:surgery; D012008:Recurrence; D012737:Sex Factors; D015996:Survival Rate; D015431:Weight Loss