Obesity is a major public health problem leading to co-morbidities such as diabetes, hypertension and kidney failure. Bariatric surgery results in pronounced and maintained weight loss and prevention of obesity-related diseases and their complications. Most studies of bariatric surgery on kidney disease show improvements after surgery. However, long-term studies analyzing hard end-points are lacking. Here we report on the long-term effects of bariatric surgery compared to usual obesity care on incidence of end-stage renal disease (ESRD) alone and in combination with chronic kidney disease stage 4 (CKD4/ESRD).
4047 patients were included in the Swedish Obese Subjects (SOS) study. Inclusion criteria were age 37–60 years and BMI ≥ 34 in men and BMI ≥ 38 in women. Patients in the bariatric surgery group (N = 2010) underwent banding (18%), vertical banded gastroplasty (69%), or gastric bypass (13%); controls (N = 2037) received usual obesity care. In this analysis, patients were followed up for a median time of 18 years. The incidence of ESRD and CKD4 was obtained by crosschecking the SOS database with the Swedish National Patient Register.
During follow-up, ESRD occurred in 13 patients in the surgery group and in 26 patients in the control group (adjusted hazard ratio (HR) = 0.27; 95% CI 0.12–0.60; p = 0.001). The number of CKD4/ESRD events was 23 in the surgery group and 39 in the control group (adjusted HR = 0.33; 95% CI 0.18–0.62; p < 0.001). In both analyses, bariatric surgery had a more favorable effect in patients with baseline serum insulin levels above median compared to those with lower insulin levels (interaction p = 0.010). Treatment benefit of bariatric surgery was also greater in patients with macroalbuminuria at baseline compared to those without macroalbuminuria (interaction p < 0.001).
Our study showed for the first time that bariatric surgery is associated with a long-term protection against ESRD and CKD4/ESRD.
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This project was supported by grants from the US National Institute of Diabetes and Digestive and Kidney Diseases (R01DK105948), the Swedish Research Council (K2013-99 × -22279-01, K2013-54 × -11285-19), Sahlgrenska University Hospital Regional Agreement on Medical Education and Research, and the Swedish Diabetes Foundation. The content is solely the responsibility of the authors and does not necessarily represent the official views of the US National Institutes of Health. We thank the staff members at the SOS Secretariat and at 480 primary health care centers and 25 surgical departments in Sweden that participated in the study.
JCA-A and MT provided data collection and linkage with the Swedish authorities. MP and JCA-A had access to all the data in the study and were responsible for acquisition and integrity of the data. MP and AS were responsible for the accuracy of the statistical data analysis. AS, MP, CDS, JCA-A, MT, KS, CWlR, LMSC, and P-AS were responsible for interpretation of the data. AS and P-AS drafted the manuscript. All authors participated in critical revision of the manuscript and provided intellectual input. LMSC, PAS, JCA-A, KS, and MT were involved in fundraising. All authors approved the final version and agree to be accountable for all aspects of the work.