title: Re-examining the BMI threshold for bariatric surgery in the USA.
abstract: BACKGROUND
  The optimal BMI threshold above which gastric bypass surgery should be offered to obese patients is controversial. The objective of this study was to compare the impact of Roux-en-Y gastric bypass (RYGB) vs. diet and exercise (D&E) on life expectancy to find the BMI at which patients experience an improvement in their life expectancy by undergoing surgery.
  
  
  METHODS
  A Markov state transition model was designed to implement a decision tree that simulated the lives of obese patients. Life expectancies following RYGB and 2 years of D&E were estimated and compared. Ten thousand patients' lives were simulated in each weight-loss intervention group in the model. In addition to base case analysis (45 kg/m(2) BMI pre-intervention), sensitivity analysis of initial BMI at the start of the study was completed. Markov model parameters were extracted from the literature.
  
  
  RESULTS
  The impact of RYGB on survival relative to D&E depended on the patient's initial BMI. Compared to patients who underwent 2 years of "optimal" diet and exercise (7 % total body weight loss/year), RYGB improved long-term survival for patients above a BMI of 31.3 kg/m(2).
  
  
  CONCLUSIONS
  Roux-en-Y gastric bypass can improve long-term survival for patients with class I obesity. This study suggests that RYGB should not be reserved solely for patients with class II or III obesity.
authors.affiliation: Johns Hopkins Hospital, Baltimore, MD, USA, rashikhc@gmail.com.
authors.forename: Rashikh A
authors.initials: RA
authors.lastname: Choudhury
authors.forename: K M
authors.initials: KM
authors.lastname: Murayama
authors.forename: C J
authors.initials: CJ
authors.lastname: Neylan
authors.forename: G
authors.initials: G
authors.lastname: Savulionyte
authors.forename: H A
authors.initials: HA
authors.lastname: Glick
authors.forename: N N
authors.initials: NN
authors.lastname: Williams
authors.forename: D T
authors.initials: DT
authors.lastname: Dempsey
authors.forename: K R
authors.initials: KR
authors.lastname: Dumon
mesh_terms: D050110:Bariatric Surgery; D015992:Body Mass Index; D003661:Decision Support Techniques; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008017:Life Expectancy; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000401:mortality / Q000601:surgery*; D011184:Postoperative Period; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D014481:United States / Q000453:epidemiology; D015431:Weight Loss / Q000502:physiology*