title: Overall and cause-specific mortality after Roux-en-Y gastric bypass surgery: A nationwide cohort study.
abstract: BACKGROUND
  Few population-based studies provide data on mortality after bariatric surgery. We hypothesized that hypoglycemia could be an underdiagnosed cause of death.
  
  
  OBJECTIVE
  To examine perioperative, all-cause, and cause-specific long-term mortality in Roux-en-Y gastric bypass (RYGB) patients versus population comparisons.
  
  
  METHODS
  Danish nationwide population-based cohort study.
  
  
  METHODS
  We included all 9895 patients who underwent RYGB during 2006-2010, and a 1:25 age- and gender-matched comparison cohort (n = 247,366) (0.3% lost to follow up). We compared mortality rates and computed mortality rate ratios (MRR) for all-cause and cause-specific mortality using Cox regression analysis. For deceased RYGB patients (n = 91), we conducted a detailed medical record audit.
  
  
  RESULTS
  The perioperative (30-days) mortality after RYGB was .04% (4/9895). After 4.2 years, RYGB-related mortality (deaths due to intestinal obstruction/intra-abdominal leakage) was .15% (16/9895). All-cause mortality was very similar in the 2 cohorts (median age, 40.2 years; 21.7% men): RYGB cohort, .89% (n = 91); comparison cohort, .92% (n = 2204); MRR = 1.03 (95% confidence interval [CI], .84-1.27). Mortality due to suicide (2.78; 95% CI, 1.44-5.33), accidents (2.29; 95% CI, 1.16-4.54), gastrointestinal diseases (2.01; 95% CI, 1.06-3.84), and infectious diseases (1.75; 95% CI, .98-3.17) was higher in the RYGB cohort versus comparison groups, but mortality from cancer was lower (0.43; 95% CI, .27-.70). Our medical record audit indicated that 8% of deaths after RYGB (n = 7) were possibly hypoglycemia related.
  
  
  CONCLUSIONS
  Perioperative mortality after RYGB is low in Denmark, and subsequent all-cause mortality is similar to that of matched comparisons. After RYGB, patients have substantially increased mortality due to external causes such as suicide, accidents, and possibly hypoglycemia.
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: sigrgrib@rm.dk.
authors.forename: Sigrid Bjerge
authors.initials: SB
authors.lastname: Gribsholt
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Reimar Wernich
authors.initials: RW
authors.lastname: Thomsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Svensson
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Bjørn
authors.initials: B
authors.lastname: Richelsen
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002423:Cause of Death / Q000639:trends; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass / Q000401:mortality*; D006801:Humans; D008297:Male; D009767:Obesity, Morbid / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D011159:Population Surveillance; D011183:Postoperative Complications / Q000401:mortality*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D015431:Weight Loss / Q000502:physiology*
keywords: Bariatric surgery; Roux-en-Y gastric bypass surgery; hypoglycemia; mortality