title: Bariatric surgery and its impact on cardiovascular disease and mortality: a systematic review and meta-analysis.
abstract: BACKGROUND
  Bariatric surgery has been shown to improve cardiovascular risk factors but long term benefits for survival and cardiovascular events are still uncertain.
  
  
  METHODS
  We searched MEDLINE and EMBASE for parallel group studies that evaluated the clinical outcomes associated with bariatric surgery as compared to non-surgical treatment. Relevant studies were pooled using random effects meta-analysis for risk of myocardial infarction, stroke, cardiovascular events and mortality.
  
  
  RESULTS
  14 studies met the inclusion criteria, which included 29,208 patients who underwent bariatric surgery and 166,200 nonsurgical controls (mean age 48 years, 30% male, follow up period ranged from 2 years to 14.7 years). Four studies were considered at moderate-high risk of bias, whilst ten studies were at moderate or lower risk of bias. Compared to nonsurgical controls there was more than 50% reduction in mortality amongst patients who had bariatric surgery (OR 0.48 95% CI 0.35-0.64, I2=86%, 14 studies). In pooled analysis of four studies with adjusted data, bariatric surgery was associated with a significantly reduced risk of composite cardiovascular adverse events (OR 0.54 95% CI 0.41-0.70, I2=58%). Bariatric surgery was also associated with significant reduction in specific endpoints of myocardial infarction (OR 0.46 95% CI 0.30-0.69, I2=79%, 4 studies) and stroke (OR 0.49 95% CI 0.32-0.75, I2=59%, 4 studies).
  
  
  CONCLUSIONS
  Data from observational studies indicates that patients undergoing bariatric surgery have a reduced risk of myocardial infarction, stroke, cardiovascular events and mortality compared to non-surgical controls. Future randomized studies should investigate whether these observations are reproduced in a clinical trials setting.
authors.affiliation: Cardiovascular Institute, University of Manchester, Manchester, UK. Electronic address: shingkwok@doctors.org.uk.
authors.forename: Chun Shing
authors.initials: CS
authors.lastname: Kwok
authors.affiliation: Royal Preston Hospital, Fulwood, Preston, UK.
authors.forename: Ashish
authors.initials: A
authors.lastname: Pradhan
authors.affiliation: Cardiovascular Institute, University of Manchester, Manchester, UK.
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Khan
authors.affiliation: Cardiovascular Institute, University of Manchester, Manchester, UK.
authors.forename: Simon G
authors.initials: SG
authors.lastname: Anderson
authors.affiliation: Cardiovascular Institute, University of Manchester, Manchester, UK.
authors.forename: Bernard D
authors.initials: BD
authors.lastname: Keavney
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen, Foresterhill, Aberdeen, UK.
authors.forename: Phyo Kyaw
authors.initials: PK
authors.lastname: Myint
authors.affiliation: Cardiovascular Institute, University of Manchester, Manchester, UK.
authors.forename: Mamas A
authors.initials: MA
authors.lastname: Mamas
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, UK.
authors.forename: Yoon K
authors.initials: YK
authors.lastname: Loke
mesh_terms: D050110:Bariatric Surgery / Q000401:mortality*; D002318:Cardiovascular Diseases / Q000401:mortality* / Q000517:prevention & control*; D006801:Humans; D009026:Mortality / Q000639:trends; D009765:Obesity / Q000401:mortality / Q000601:surgery; D064887:Observational Studies as Topic / Q000401:mortality; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000401:mortality / Q000517:prevention & control; D015431:Weight Loss / Q000502:physiology
keywords: Bariatric surgery; Cardiovascular disease; Mortality; Myocardial infarction; Obesity; Stroke