Impact of Early Postbariatric Surgery Acute Kidney Injury on Long-Term Renal Function

Predictors and outcomes of acute kidney injury after bariatric surgery: analysis of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program data registry

BACKGROUND

Acute kidney injury (AKI) after surgery increases long-term risk of kidney dysfunction. The major risk factor for AKI after bariatric surgery is having preoperative renal insufficiency. Little is known about the outcomes and risk factors for developing AKI in patients undergoing bariatric surgery with normal renal function.

OBJECTIVE

We aimed to describe factors that may increase risk of AKI after primary bariatric surgery in patients without history of kidney disease.

SETTING

Academic hospital, United States.

METHODS

We performed a retrospective analysis of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program data registry for patients aged ≥18 years undergoing laparoscopic sleeve gastrectomy and laparoscopic Roux-en-Y gastric bypass (LRYGB) from 2015 to 2019. Patients with diagnosis of chronic kidney disease were excluded. The primary outcome was incidence of AKI. Secondary outcomes included 30-day complications, readmissions, reoperations, and mortality. Univariate and multivariate analyses were performed to identify differences between patients with and without AKI.

RESULTS

A total of 747,926 patients were included in our analysis (laparoscopic sleeve gastrectomy = 73.1%, LRYGB = 26.8%). Mean age was 44.40 ± 11.94 years, with female predominance (79.7%). AKI occurred in 446 patients (.05%). Patients with postoperative AKI had higher rates of complications, readmissions, reoperations, and mortality. Significant predictors of AKI were male sex, history of venous thromboembolism, hypertension, limitation for ambulation, and LRYGB. High albumin levels and White race were protective factors.

CONCLUSIONS

New-onset AKI was associated with adverse 30-day outcomes in patients undergoing bariatric surgery. Male sex, venous thromboembolism, hypertension, limited ambulation, and LRYGB were independent predictors of AKI. Prospective studies are needed to better describe these results.

Acute post sleeve surgery bleeding as rare cause of acute renal failure: a case report

BACKGROUND

Bariatric surgeries have been considered as one of the most important treatment procedures in recent years. Being aware of the side effects of this surgery will lead to better results after the surgery.

CASE PRESENTATION

A 37-year-old Iranian male patient presented one day after sleeve surgery with symptoms of weakness, lethargy, and shortness of breath, which hospitalization and workup to were done to rule out pulmonary embolism. Because of the high creatinine and anuria, we couldn't perform computed tomography angiography. A bedside ultrasound was done for the patient and showed a mild to moderate amount of fluid around the spleen and some blood clots. Due to the progressive clinical findings and suspected internal bleeding, the patient was a candidate for laparoscopic revision procedure. Gradually, after performing the surgery, removing the blood clot and reducing the compressive effect of that on the inferior verna cava which was the main reason of renal failure, the patient was able to urinate afterwards and was discharged in good general condition.

CONCLUSION

Surgeons should be aware of the management of rare surgical complications after bariatric surgeries. To be best of our knowledge, this was the first case report of a patient with acute renal failure after bariatric surgery and the rare cause of clot compression on inferior vena cava and raised abdominal compartment pressure.

Obesity and renal disease: Benefits of bariatric surgery

The prevalence of obesity, a preventable and reversible condition with a high impact on health, continues to rise, especially after the COVID-19 pandemic. Severe overweight is well recognized as a risk factor for diabetes and hypertension, among other conditions, that may increase cardiovascular risk. Obesity has grown simultaneously with a rise in the prevalence of chronic kidney disease, and a pathophysiological link has been established, which explains its role in generating the conditions to facilitate the emergence and maximize the impact of the risk factors of chronic kidney disease and its progression to more advanced stages. Knowing the mechanisms involved and having different tools to reverse the overweight and its consequences, bariatric surgery has arisen as a useful and efficient method, complementary or alternative to others, such as lifestyle changes and/or pharmacotherapy. In a detailed review, the mechanisms involved in the renal consequences of obesity, the impact on risk factors, and the potential benefit of bariatric surgery at different stages of the disease and its progression are exposed and analyzed. Although the observational evidence supports the value of bariatric surgery as a renoprotective measure in individuals with obesity, diabetic or not, randomized studies are expected to establish evidence-based recommendations that demonstrate its positive risk-benefit balance as a complementary or alternative therapeutic tool.

Thirty-Day Readmission After Bariatric Surgery: Causes, Effects on Outcomes, and Predictors

BACKGROUND

Bariatric surgery (BSx) is one of the most common surgical procedures in North America. Readmissions may be associated with a high burden to the healthcare system.

METHODS

Retrospective study of the 2016 National Readmission Database of adult patients readmitted within 30 days after an index admission for BSx. Outcomes were: 30-day readmission rate, mortality, healthcare-related utilization resources, and independent predictors of readmission. Comparison groups were index admission, readmitted, and non-readmitted patients.

RESULTS

A total of 161,141 patients underwent BSx. The 30-day readmission rate was 3.3%. Main causes for readmission were dehydration, acute kidney injury, venous thromboembolism events, and sepsis. Readmitted patients were more likely to develop shock (0.5% vs. 0.1%; P < 0.01) with no differences in mechanical ventilation (1.9% vs. 2.0%; P = 0.83) during index admission compared to non-readmitted patients. Readmission was associated with higher in-hospital mortality rate (1.5% vs. 0.1%; P < 0.01) and prolonged length of stay (4.6 vs. 2.4 days; P < 0.01). The total in-hospital economic burden of readmission was $234 million in total charges and $58.7 million in total costs. Independent predictors of readmission were: Charlson comorbidity index of ≥ 3, longer length of stay, admission to larger bed size hospitals, discharge to nursing home, and acute kidney injury. Medicaid, private insurance, BMI of 30-39 kg/m², and 40-44 kg/m² were associated with lower odds for readmission.

CONCLUSION

Readmissions after BSx are associated with higher in-hospital mortality rate and pose a high healthcare burden. We identified risk factors that can be targeted to decrease readmissions after BSx, healthcare burden, and patient morbidity and mortality.

A low serum iron level is a potential predictor of poor renal function in patients following laparoscopic sleeve gastrectomy: a retrospective study

This study aimed to assess the association of serum iron level (Iron) with the estimated glomerular filtration rate (eGFR) after bariatric surgery (BS). We reviewed 210 patients with mean age of 39.1 ± 10.6 years (body mass index, 41.4 ± 5.5 kg/m²) undergoing BS. The primary outcome was the relationship between Iron and eGFR at 12-month after surgery. Multiple linear regression analyses were performed using postoperative eGFR as dependent variables and using Iron and other variables (i.e., age) as independent variables. At 12-month follow-up, 94 patients were analyzed. BMI significantly decreased, whereas serum iron level significantly increased. Although the percentage of patients with eGFR of < 90 mL/min/1.73 m² increased during the study period, no significant difference was found in postoperative 12-month eGFR. No correlations were noted between Iron and eGFR at baseline and postoperative 1 and 6 months, whereas a significant relationship was observed between Iron and postoperative 12-month eGFR. Multiple linear regression analyses revealed that Iron and presence of diabetes were the independent predictors of postoperative 12-month eGFR. This pilot study showed a positive association of postoperative serum iron level with renal function in this patient population. Further large-scale trials are needed to confirm the findings.

Obesity-Related Glomerulopathy: Clinical Management

Obesity-related glomerulopathy (ORG) and other obesity-associated kidney diseases pose a major challenge to the treating nephrologist. We review the benefits of weight loss and optimal management of ORG and kidney disease in the setting of obesity. Therapeutic strategies in ORG were limited mainly in the past to weight loss through lifestyle interventions and bariatric surgery, antihypertensive treatment, and renin-angiotensin-aldosterone system blockade. Current approaches to obtain the desired weight loss include novel pharmacologic therapies that have been approved for the treatment of diabetes while offering kidney protection, such as sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide-1-receptor agonists. This review focuses on the nephroprotective role of the renin-angiotensin-aldosterone system blockade and of these new pharmacologic agents, and on the renal effects of bariatric surgery in chronic kidney disease.

IS BODY MASS INDEX AND OBESITY SURGERY MORTALITY SCORE IMPORTANT IN PERIOPERATIVE COMPLICATIONS OF LAPAROSCOPIC SLEEVE GASTRECTOMY BEFORE DISCHARGE?

Background:

Morbid obesity surgery and related complications have increased with time.

Aim:

To evaluate the relationship between perioperative complications before discharge and preoperative body mass index and obesity surgery mortality score in laparoscopic sleeve gastrectomy.

Method:

1617 patients who met the inclusion criteria were evaluated retrospectively. The patients were examined in terms of demographic data, presence of comorbidities, whether there were complications or not, type of complications and obesity surgery mortality score.

Results:

Complications were seen in 40 patients (2.5%) and mortality wasn’t seen in the early postoperative period before discharge. The mean age of patients with complications was 36.3±10.02 years (19-57) and without complications 34.12±9.54 (15-64) years. The preoperative mean BMI values of patients with and without complications were 45.05±3.93 (40-57) kg/m² and 44.8±3.49 (35-67) kg/m² respectively. According to BMI groups 40-45 kg/m², 45-50 kg/m² and 50 and over, there was not any statistical significance seen in three groups in terms of complication positivity and major-minor complication rates. There was not any statistical significance seen between the patients with and without major-minor complications and obesity surgery mortality score.

Conclusion:

There was not any relation between perioperative laparoscopic sleeve gastrectomy complication rates before discharge and BMI and obesity surgery mortality scores.

Perioperative Risks of Sleeve Gastrectomy Versus Roux-en-Y Gastric Bypass Among Patients With Chronic Kidney Disease: A Review of the MBSAQIP Database

OBJECTIVE

To determine whether patients with CKD experience higher rates of perioperative complications after RYGB compared to sleeve gastrectomy.

SUMMARY OF BACKGROUND DATA

For obese CKD patients who qualify for bariatric surgery, sleeve gastrectomy is often preferred to RYGB based on perceptions of prohibitively-high perioperative risks surrounding RYGB. However, some patients with CKD are not candidates for sleeve gastrectomy and the incremental increased-risk from RYGB has never been rigorously tested in this population.

METHODS

CKD patients who underwent RYGB or sleeve gastrectomy between 2015 and 2017 were identified from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program Participant Use File. RYGB patients were 1:1 propensity-score matched with sleeve gastrectomy patients based on preoperative factors that influence operative choice. Primary outcomes included 30-day readmissions, surgical complications, medical complications, and death. Secondary outcomes included the individual complications used to create the composite surgical/medical complications. Univariate logistic regression was used to compare outcomes. E-value statistic was used to test the strength of outcome point estimates against possible unmeasured confounding.

RESULTS

Demographics were similar between RYGB (n = 673) and sleeve gastrectomy (n = 673) cohorts. There were no statistically significant differences in primary outcomes. Among secondary outcomes, only acute kidney injury was statistically-significantly higher among RYGB patients (4.9% vs 2.7%, P = 0.035, E-value 1.27).

CONCLUSIONS

Among well-matched cohorts of RYGB and sleeve gastrectomy patients, incidence of primary outcomes were similar. Among secondary outcomes, only acute kidney injury was statistically-significantly higher among RYGB patients; however, the E-value for this difference was small and relatively weak confounder(s) could abrogate the statistical difference. The perception that RYGB has prohibitively-high perioperative risks among CKD patients is disputable and operative selection should be weighed on patient candidacy and anticipated long-term benefit.

The Impact of Bariatric Surgery on Renal Function: a Retrospective Analysis of Short-Term Outcomes

PURPOSE

Obesity and diabetes mellitus are now leading causes of chronic kidney disease. Our study investigated the effects of bariatric surgery on estimated glomerular filtration (eGFR) and urinary microalbumin/creatinine ratio (ACR) in morbidly obese patients.

MATERIALS AND METHODS

The clinical materials for patients who underwent bariatric surgery were retrospectively analyzed with a 6-month follow-up period between January 1, 2018, and June 1, 2020. The eGFR (ml/min) was calculated using the Cockcroft-Gault formula equation. The urinary ACR was measured during the follow-up. Body mass index (BMI, kg/m²), percent weight loss (%WL), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were recorded during the follow-up.

RESULTS

Sixty-one patients who underwent bariatric surgery-laparoscopic Roux-en-Y gastric bypass (LRYGB; n = 22) and laparoscopic sleeve gastrectomy (LSG; n = 39)-were included in this study. The eGFR of both groups decreased at the follow-up outpatient visits (p < 0.001), although eGFR did not differ between the two groups. Unexpectedly, the ACR increased in the first month after LSG (p < 0.01) but decreased with a descending trend with no significant difference (p > 0.05) throughout the remaining follow-up period. Interestingly, ACR showed a descending trend with no significant difference during the follow-up in the LRYGB group (p > 0.05). The SBP and DBP decreased after bariatric surgery, with no significant difference between the two groups (p > 0.05).

CONCLUSION

Bariatric surgery is associated with improvements in postoperative renal function 6 months following surgery. The different alterations in ACR following LSG and LRYGB procedures demonstrate the underlying mechanism.

Association of Serum Zinc Concentration with Preservation of Renal Function After Bariatric Surgery: a Retrospective Pilot Study

BACKGROUND

Although serum zinc level (Zn) is known to impact renal function in patients with diabetes, their correlation following bariatric surgery remains unknown. This study aimed at assessing the association of Zn with estimated glomerular filtration rate (eGFR) after laparoscopic sleeve gastrectomy (LSG).

METHODS

One hundred and twenty-nine patients in total (mean age, 38.1 ± 10.8; body mass index, 39.1 ± 5.1 kg/m²) with normal preoperative kidney function undergoing LSG at a single tertiary referral center were reviewed. The primary study endpoint was the relationship between Zn and post-LSG eGFR at 12-month follow-up. The secondary outcomes were the associations of percentage weight loss (%WL) with changes in Zn (△Zn) and eGFR (△eGFR).

RESULTS

The incidence of zinc deficiency was 8.5%, 8.1%, and 29.9% at baseline, post-LSG and one- and 12-month follow-up, respectively. At 12-month follow-up, Zn dropped from 104.1 ± 19.2 to 85.3 ± 38.9 μg/dL (p = 0.001), while eGFR levels decreased from 106.6 ± 10.3 to 102.1 ± 19.4 mL/min per 1.73 m² (p = 0.025). Zn correlated positively with eGFR at 6-month (r = 0.252, p = 0.037) and 12-month (r = 0.41, p = 0.001) follow-ups. Multiple linear regression analyses including baseline variables of age, sex, BMI, %WL, and diabetes identified Zn and %WL as independent predictors of eGFR at 12-month follow-up. There was no evidence of multicollinearity among these variables. Despite positive association between %WL and △eGFR (r = 0.222, p = 0.031), no correlation was noted between %WL and △Zn (r = - 0.129, p = 0.40).

CONCLUSION

The results demonstrated a positive relationship between post-LSG serum zinc levels and preservation of renal function among patients with obesity in a surgical setting. Large-scale studies are warranted to support the findings.

Management of Obesity in Adults with CKD

Obesity is a leading public health problem that currently affects over 650 million individuals worldwide. Although interest in the adverse effects of obesity has grown exponentially in recent years, less attention has been given to studying its management in individuals with CKD. This relatively unexplored area should be considered a high priority because of the rapid growth and high prevalence of obesity in the CKD population, its broad impact on health and outcomes, and its modifiable nature. This article begins to lay the groundwork in this field by providing a comprehensive overview that critically evaluates the available evidence related to obesity and kidney disease, identifies important gaps in our knowledge base, and integrates recent insights in the pathophysiology of obesity to help provide a way forward in establishing guidelines as a basis for managing obesity in CKD. Finally, the article includes a kidney-centric algorithm for management of obesity that can be used in clinical practice.

Case Report: Acute kidney failure leading to permanent haemodialysis due to hyperoxaluria following one-anastomosis gastric bypass-related rapid weight loss

The one-anastomosis gastric bypass (OAGB) has been proven to provide good weight loss, comorbidity improvement, and quality of life with follow-up longer than five years. Although capable of improving many obesity-related diseases, OAGB is associated with post-operative medical complications mainly related to the induced malabsorption. A 52-year-old man affected by nephrotic syndrome due to a focal segmental glomerulosclerosis underwent OAGB uneventfully. At three months post-surgery, the patient had lost 40kg, reaching a BMI of 32. The patient was admitted to the nephrology unit for acute kidney injury with only mild improvement in renal function (SCr 9 mg/dl); proteinuria was still elevated (4g/24h), with microhaematuria. A renal biopsy was performed: oxalate deposits were demonstrated inside tubules, associated with acute and chronic tubular and interstitial damage and glomerulosclerosis (21/33 glomeruli). Urinary oxalate levels were found to be elevated (72mg/24h, range 13-40), providing the diagnosis of acute kidney injury due to hyperoxaluria, potentially associated to OAGB. No recovery in renal function was observed and the patient remained dialysis dependent. Early and rapid excessive weight loss in patients affected by chronic kidney insufficiency could be associated with the worsening of renal function. Increased calcium oxalate levels associated with OAGB-related malabsorption could be a key factor in kidney injury.

Impact of Preoperative Anemia on Postoperative Kidney Function Following Laparoscopic Bariatric Surgery

BACKGROUND

Preoperative anemia is a risk factor for acute kidney failure after high-risk surgeries. We assessed the impact of preoperative anemia on kidney function in an obese Asian population after laparoscopic bariatric surgery.

METHODS

Patient characteristics, comorbidities, type of surgery, perioperative profiles, eGFR, and micronutrition were retrospectively reviewed in 341 patients with obesity undergoing bariatric surgery. All patients, who had a preoperative estimated glomerular filtration rates (eGFR) ≥ 90 mL/min/1.73 m², were followed for 1 year and assigned to one of two groups: anemia or non-anemia group. Preoperative anemia was determined based on hemoglobin concentration.

RESULTS

The Pearson's correlation coefficient between preoperative body mass index (BMI) and preoperative eGFR of all patients was 0.169 (p = 0.005). Preoperatively, there were no significant differences in age, BMI, and eGFR between the anemia (n = 38) and non-anemia groups (n = 303). Patients in the anemia group had lower hemoglobin concentration at baseline, 1 month, and 12 months after surgery than those in the non-anemia group. Postoperative eGFR levels at 1 month (p = 0.993) and 1 year (p = 0.118) as well as hospital stay (p = 0.941) were comparable between the two groups. However, the percentage weight loss was significantly higher in the non-anemia group than that in the anemia group 1 year after bariatric surgery (30.0 ± 7.3% vs. 27.0 ± 8.1%; p = 0.041).

CONCLUSIONS

Preoperative anemia did not negatively impact kidney function following laparoscopic bariatric surgery during the 12-month follow-up. Considering the potential adverse impact of anemia on postoperative weight loss, preoperative correction of anemia may be recommended.