title: Bariatric Surgery and Emergency Department Visits and Hospitalizations for Heart Failure Exacerbation: Population-Based, Self-Controlled Series.
abstract: BACKGROUND
  The United States is battling obesity and heart failure (HF) epidemics. Although studies have suggested relationships between obesity and HF morbidity, little is known regarding the effects of substantial weight reduction in obese patients with HF.
  
  
  OBJECTIVE
  This study investigated whether bariatric surgery is associated with a decreased rate of HF exacerbation.
  
  
  METHODS
  We performed a self-controlled case series study of obese patients with HF who underwent bariatric surgery, using the population-based emergency department (ED) and inpatient sample in California, Florida, and Nebraska. Primary outcome was ED visit or hospitalization for HF exacerbation from 2005 to 2011. We used conditional logistic regression to compare the outcome event rate during sequential 12-month periods, using pre-surgery months 13 to 24 as the reference period.
  
  
  RESULTS
  We identified 524 patients with HF who underwent bariatric surgery. During the reference period, 16.2% of patients had an ED visit or hospitalization for HF exacerbation. The rate remained unchanged in the subsequent 12-month pre-surgery period (15.3%; p = 0.67). In the first 12-month period after bariatric surgery, we observed a nonsignificantly reduced rate (12.0%; p = 0.052). However, the rate was significantly lower in the subsequent 13 to 24 months after bariatric surgery (9.9%; adjusted odds ratio: 0.57; p = 0.003). By contrast, there was no significant reduction in the rate of HF exacerbation among obese patients who underwent nonbariatric surgery (i.e., cholecystectomy, hysterectomy).
  
  
  CONCLUSIONS
  Our findings indicate that bariatric surgery is associated with a decline in the rate of HF exacerbation requiring ED evaluation or hospitalization among obese patients with HF.
authors.affiliation: Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts. Electronic address: yshimada@partners.org.
authors.forename: Yuichi J
authors.initials: YJ
authors.lastname: Shimada
authors.affiliation: Department of Health Policy and Management, Harvard T.H. Chan School of Public Health, Boston, Massachusetts.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tsugawa
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: David F M
authors.initials: DFM
authors.lastname: Brown
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Kohei
authors.initials: K
authors.lastname: Hasegawa
mesh_terms: D000328:Adult; D050110:Bariatric Surgery; D018450:Disease Progression; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000453:epidemiology / Q000628:therapy*; D006760:Hospitalization / Q000639:trends*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009017:Morbidity / Q000639:trends; D009765:Obesity / Q000150:complications / Q000453:epidemiology / Q000601:surgery*; D016017:Odds Ratio; D009819:Office Visits / Q000639:trends*; D011159:Population Surveillance; D013997:Time Factors; D014481:United States / Q000453:epidemiology
keywords: confounder; epidemic; heart failure; obesity