Vanessa Falk, MD, Curtis Marcoux, MSc, David Pace, MD, FRCSC, Felicia Pickard, MD, Priscille Cyr, MD, Smith Chris, MD, FRCSC, Darrell Boone, MD, FRCSC, Deborah Gregory, MSc, PhD, Laurie Twells, PhD. Memorial University of Newfoundland
Introduction: While obesity has been shown to contribute to both the development and progression of renal failure, the effects of bariatric surgery on post-operative renal function remain poorly understood. We hypothesize that patients who undergo a laparoscopic sleeve gastrectomy (LSG) have no deterioration of renal function regardless of their pre-operative renal function.
Methods: This is a retrospective chart review of patients who underwent LSG at a single bariatric center from May 2011 to February 2014. The primary outcomes assessed were estimated glomerular filtration rate (eGFR), serum creatinine (Cr) and urea at 6 and 12 months post-operative LSG. Data on patient demographics, pre-operative renal function, weight loss and 30-day postoperative complications were collected. Patients were further divided into normal pre-operative renal function group (NRF) with eGFR≥60 and abnormal renal function group (ARF) with eGFR<60. Paired Student t-test and independent Student t-tests were performed to compare pe-operative and post-operative renal function within each group and between groups, respectively. Chi-Squared test was used for categorical variables. Statistical analysis was performed using SPSS (Version 21).
Results: Two hundred and nine patients underwent LSG (n=209). Compared to preoperative renal function (mean Cr= 71.9±16.2umol/L), there was no difference in the renal function of patients noted at 6 months (mean Cr= 70.9±18.3 umol/L, p=0.607) and at 12 months (mean Cr= 72.2±18.1 mmol/L, p=0.807). Normal pre-operative eGFR was noted in 192 patients and abnormal renal function was noted in seventeen patients. Differences in pre-operative renal function between the NRF and ARF groups were statistically significant (mean Cr= 69.4±12.6umol/L vs. mean Cr= 108.5±29.7umol/L, p<0.001 and mean urea= 5.2±5.4mmol/L vs. mean urea= 8.1±3.1mmol/L, p<0.001). These groups were similar with regard to gender distribution (>80% female), mean pre-operative weight (135kg), body mass index (mean 49.2kg/m2) and obesity related comorbidities. The NRF group was younger (43.2 years vs, 54.0 years, p<0.001). The renal function of patients in the NRF group did not change significantly at 6 and 12 months post LSG. While not statistically significant, within the ARF group, there was a general improvement in post-operative mean eGFR and Cr at 12 months (n= 11; 51.1±8.4 vs. 54.9±7.1 ml/min/1.73m2, p=0.490, 108.5±29.7 vs. 100.1±19.6 umol/L, p=0.301). Weight loss (%EBMIL ~59%kg/m2) and post-operative complications rates were similar in both groups. No mortality occurred.
Conclusion: LSG does not appear to worsen renal function regardless of pre-operative eGFR.