title: Age- and sex-specific effects on weight loss outcomes in a comparison of sleeve gastrectomy and Roux-en-Y gastric bypass: a retrospective cohort study.
abstract: BACKGROUND
  Roux-en-Y gastric bypass (RYGBP) and sleeve gastrectomy (SG) are the most common bariatric procedures undertaken globally but there are no evidenced-based criteria that inform the selection of one operation over the other. The purpose of this study was thus to compare weight loss outcomes between RYGBP and SG, and to define patient factors affecting weight loss.
  
  
  METHODS
  A single-centre two-year follow-up retrospective cohort study of all adults who underwent either RYGBP (n = 422) or SG (n = 432) between 2007 and 2012, at University College London Hospitals National Health Service Foundation Trust, an academic tertiary referral centre, was undertaken. Multilevel linear regression was used to compare weight loss between groups, enabling adjustment for preoperative BMI (body mass index) and evaluation for interaction factors.
  
  
  RESULTS
  One- and two-year results showed that unadjusted BMI loss was similar between groups; 13.7 kg/m(2) (95% CI: 12.9, 14.6 kg/m(2)) and 12.8 kg/m(2) (95% CI: 11.8, 13.9 kg/m(2)) for RYGBP patients respectively compared with 13.3 kg/m(2) (95% CI: 12.0, 14.6 kg/m(2)) and 11.5 kg/m(2) (95% CI: 10.1, 13.0 kg/m(2)) for SG patients respectively. Adjusting for preoperative BMI, there was 2.2 kg/m(2) (95% CI: 1.5, 2.8) and 2.3 kg/m(2) (95% CI: 1.3, 3.3) greater BMI loss in the RYGBP group compared to the SG group at one and two years respectively (P < 0.001 for both). The interaction analyses demonstrated that age and sex had important differential impacts on SG and RYGBP weight outcomes. Men under 40 and women over 50 years obtained on average far less benefit from SG compared to RYGBP, whereas men over 40 years and women under 50 years experienced similar weight loss with either procedure (P = 0.001 and 0.022 for interaction effects at one and two years respectively).
  
  
  CONCLUSIONS
  Our results show that patient sex and age significantly impact on weight loss in a procedure-dependent manner and should be considered when choosing between RYGBP and SG. Optimizing procedure selection could enhance the effectiveness of bariatric surgery, thus further increasing the benefit-to-risk ratio of this highly effective intervention.
authors.affiliation: Centre for Obesity Research, Rayne Institute, Department of Medicine, University College London, Rayne Building, 5 University Street, London, WC1E 6JJ UK ; UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK ; National Institute of Health Research University College London Hospitals Biomedical Research Centre, London, W1T 7DN UK.
authors.forename: Sean
authors.initials: S
authors.lastname: Manning
authors.affiliation: Queen Alexandra Hospital, Southwick Hill Road, Portsmouth, PO6 3LY UK.
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Carter
authors.affiliation: Centre for Obesity Research, Rayne Institute, Department of Medicine, University College London, Rayne Building, 5 University Street, London, WC1E 6JJ UK ; UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pucci
authors.affiliation: University College London Institute of Cardiovascular Science, 170 Tottenham Court Road, London, W1T 7HA UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Jones
authors.affiliation: UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK ; Clinical and Experimental Surgery Department, Medical Research Institute, University of Alexandria, Hadara, Alexandria, 21561 Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Elkalaawy
authors.affiliation: Centre for Obesity Research, Rayne Institute, Department of Medicine, University College London, Rayne Building, 5 University Street, London, WC1E 6JJ UK ; UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK.
authors.forename: Wui-Hang
authors.initials: WH
authors.lastname: Cheung
authors.affiliation: UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK.
authors.forename: Borzoueh
authors.initials: B
authors.lastname: Mohammadi
authors.affiliation: UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK ; University College London Institute of Cardiovascular Science, 170 Tottenham Court Road, London, W1T 7HA UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Finer
authors.affiliation: Surrey Weight Loss Centre, St Anthony's Hospital, North Cheam, SM3 9DW UK.
authors.forename: Alberic G
authors.initials: AG
authors.lastname: Fiennes
authors.affiliation: UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK.
authors.forename: Majid
authors.initials: M
authors.lastname: Hashemi
authors.affiliation: UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Jenkinson
authors.affiliation: UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK.
authors.forename: Marco
authors.initials: M
authors.lastname: Adamo
authors.affiliation: Centre for Obesity Research, Rayne Institute, Department of Medicine, University College London, Rayne Building, 5 University Street, London, WC1E 6JJ UK ; UCLH Centre for Weight Loss, Metabolic and Endocrine Surgery, University College London Hospitals, Ground Floor West Wing, 250 Euston Road, London, NW1 2PG UK ; National Institute of Health Research University College London Hospitals Biomedical Research Centre, London, W1T 7DN UK.
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Batterham
keywords: BMI; Bariatric surgery; Diabetes; Gastric bypass; Obesity; Sleeve gastrectomy; Weight loss