Effect of Gastric Bypass Surgery on Kidney Stone Disease
Received 15 October 2008 published online 16 April 2009.
Purpose
Recent studies have demonstrated that mineral and electrolyte abnormalities develop in patients who undergo bariatric surgery. While it is known that these abnormalities are a risk factor for urolithiasis, the prevalence of stone disease after bariatric surgery is unknown. We evaluated the likelihood of being diagnosed with or treated for an upper urinary tract calculus following Roux-en-Y gastric bypass surgery.
Materials and Methods
We identified 4,639 patients who underwent Roux-en-Y gastric bypass surgery and a control group of 4,639 obese patients who did not have surgery in a national private insurance claims database in a 5-year period (2002 to 2006). All patients had at least 3 years of continuous claims data. Our 2 primary outcomes were the diagnosis and the surgical treatment of a urinary calculus.
Results
After Roux-en-Y gastric bypass surgery 7.65% (355 of 4,639) of patients were diagnosed with urolithiasis compared to 4.63% (215 of 4,639) of obese patients in the control group (p <0.0001). Subjects in the treatment cohort more commonly underwent shock wave lithotripsy (81 [1.75%] vs 19 [0.41%], p <0.0001) and ureteroscopy (98 [2.11%] vs 27 [0.58%], p <0.0001). Logistic regression demonstrated that Roux-en-Y gastric bypass surgery was a significant predictor of being diagnosed with a urinary calculus (OR 1.71, CI 1.44–2.04) as well as undergoing a surgical procedure (OR 3.65, CI 2.60–5.14).
Conclusions
Roux-en-Y gastric bypass surgery is associated with an increased risk of kidney stone disease and kidney stone surgery in the postoperative period. Clinicians should be aware of this hazard and inform patients of this potential complication. Future studies are needed to evaluate preventive measures in the high risk population.
Departments of Urology, Surgery, Anesthesiology and Medicine, the Johns Hopkins University School of Medicine, and the Departments of Health Policy and Management, Johns Hopkins School of Public Health, Baltimore, Maryland
Correspondence: James Buchanan Brady Urological Institute, The Johns Hopkins University School of Medicine, 600 North Wolfe St., Baltimore, Maryland 21287 (telephone: 410-550-3506; FAX: 410-550-3341)
Supported by The Hariri Family Foundation, and Mr. and Mrs. Chad and Nissa Richinson.
The data set used in this study was originally created for a different research project on patterns of obesity care within selected BCBS plans. The previous research project (but not the current study) was funded by unrestricted research grants from Ethicon Endo-Surgery, Inc. (a Johnson & Johnson company); Pfizer, Inc and GlaxoSmithKline. The data and database development support and guidance were provided by the BCBS Association, BCBS of Tennessee, BCBS of Hawaii, BCBS of Michigan, BCBS of North Carolina, Highmark, Inc. of Pennsylvania, Independence Blue Cross of Pennsylvania, Wellmark BCBS of Iowa and Wellmark BCBS of South Dakota.
ABSTRACT