title: The risk of kidney stones following bariatric surgery: a systematic review and meta-analysis.
abstract: BACKGROUND
  With rising prevalence of morbid obesity, the number of bariatric surgeries performed each year has been increasing worldwide. The objective of this meta-analysis was to assess the risk of kidney stones following bariatric surgery.
  
  
  METHODS
  A literature search was performed using MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews from inception through July 2015. Only studies reporting relative risks, odd ratios or hazard ratios (HRs) to compare risk of kidney stones in patients who underwent bariatric surgery versus no surgery were included. Pooled risk ratios (RR) and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method.
  
  
  RESULTS
  Four studies (One randomized controlled trial and three cohort studies) with 11,348 patients were included in analysis to assess the risk of kidney stones following bariatric surgery. The pooled RR of kidney stones in patients undergoing bariatric surgery was 1.22 (95% CI, 0.63-2.35). The type of bariatric surgery subgroup analysis demonstrated an increased risk of kidney stones in patients following Roux-en-Y gastric bypass (RYGB) with the pooled RR of 1.73 (95% CI, 1.30-2.30) and a decreased risk of kidney stones in patients following restrictive procedures including laparoscopic banding or sleeve gastrectomy with the pooled RR of 0.37 (95% CI, 0.16-0.85).
  
  
  CONCLUSIONS
  Our meta-analysis demonstrates an association between RYGB and increased risk of kidney stones. Restrictive bariatric surgery, on the other hand, may decrease kidney stone risk. Future study with long-term follow-up data is needed to confirm this potential benefit of restrictive bariatric surgery.
authors.affiliation: a Division of Nephrology and Hypertension , Mayo Clinic , Rochester , MN , USA ;
authors.forename: Charat
authors.initials: C
authors.lastname: Thongprayoon
authors.affiliation: a Division of Nephrology and Hypertension , Mayo Clinic , Rochester , MN , USA ;
authors.forename: Wisit
authors.initials: W
authors.lastname: Cheungpasitporn
authors.affiliation: b Department of Internal Medicine , Mayo Clinic , Rochester , MN , USA ;
authors.forename: Priya
authors.initials: P
authors.lastname: Vijayvargiya
authors.affiliation: c Division of Endocrinology , Mayo Clinic , Rochester , MN , USA ;|d Faculty of Medicine , Thammasat University Hospital , Bangkok , Thailand.
authors.forename: Pimjai
authors.initials: P
authors.lastname: Anthanont
authors.affiliation: a Division of Nephrology and Hypertension , Mayo Clinic , Rochester , MN , USA ;
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Erickson
mesh_terms: D015390:Gastric Bypass / Q000009:adverse effects*; D006801:Humans; D007669:Kidney Calculi / Q000453:epidemiology*; D010535:Laparoscopy / Q000379:methods; D009767:Obesity, Morbid / Q000601:surgery*; D016017:Odds Ratio; D011183:Postoperative Complications / Q000453:epidemiology*; D016032:Randomized Controlled Trials as Topic; D015431:Weight Loss
keywords: Bariatric surgery; gastric bypass surgery; kidney stones; nephrolithiasis; obesity