Determinants of glomerular filtration rate following bariatric surgery in individuals with severe, otherwise uncomplicated, obesity: an observational, prospective study

Longitudinal Effect of Bariatric Surgery on Retinal Microcirculation and Target Organ Damage: the BASTOD Study

PURPOSE

Obesity is associated with increased cardiovascular risk. Bariatric surgery (BS) improves the clinical and metabolic profile. Retinal caliber changes could precede cardiovascular events. Different studies have shown an improvement in retinal caliber after BS. The aim of this study was to examine retinal caliber and other cardiovascular target organ damage before and after BS.

MATERIALS AND METHODS

Monocentric, prospective cohort study at the Montpellier University Hospital. Biologic features, vessel stiffness, echocardiograph variables, and retinal caliber at baseline and 6 and 12 months were assessed in consecutive patients with class 2 or 3 obesity undergoing BS. A mixed linear model adjusted for age and sex was used.

RESULTS

We included 88 patients (75 women). The mean (SD) age was 43 years (11) and mean (SD) baseline weight 117 (21) Kg. Mean changes in the first year after BS were - 5.1 µm in central retinal vein equivalent (CRVE) (p < 0.0001), + 0.02 in arteriole-to-venule ratio (AVR) (p < 0.0001), - 1.4 mmol/L in glycemia (p < 0.0001), - 1.0 mg/L in natural logarithm of C-reactive protein (p < 0.0001), and - 54.0 g in left ventricular mass (p = 0.0005). We observed no significant improvement in arterial stiffness markers. Predictors of improvement in CRVE were high baseline weight (p = 0.030), male sex (p = 0.025), and no diabetes history (p Dynamic links between variations = 0.047).

CONCLUSION

The retinal microvascular phenotype improved during the first year after bariatric surgery, with decreased CRVE and increased AVR. Factors associated with retinal microvascular plasticity were male sex, high baseline weight, and absence of diabetes. Longitudinal assessment of retinal vascular calibers may offer new insights into the pathophysiology of subclinical vascular processes.

Range of adiposity and cardiorenal syndrome

Obesity and obesity-related co-morbidities, diabetes mellitus, and hypertension are among the fastest-growing risk factors of heart failure and kidney disease worldwide. Obesity, which is not a unitary concept, or a static process, ranges from alterations in distribution to the amount of adiposity. Visceral adiposity, which includes intraabdominal visceral fat mass and ectopic fat deposition such as hepatic, cardiac, or renal, was robustly associated with a greater risk for cardiorenal morbidity than subcutaneous adiposity. In addition, morbid obesity has also demonstrated a negative effect on cardiac and renal functioning. The mechanisms by which adipose tissue is linked with the cardiorenal syndrome (CRS) are hemodynamic and mechanical changes, as well neurohumoral pathways such as insulin resistance, endothelial dysfunction, nitric oxide bioavailability, renin-angiotensin-aldosterone, oxidative stress, sympathetic nervous systems, natriuretic peptides, adipokines and inflammation. Adiposity and other associated co-morbidities induce adverse cardiac remodeling and interstitial fibrosis. Heart failure with preserved ejection fraction has been associated with obesity-related functional and structural abnormalities. Obesity might also impair kidney function through hyperfiltration, increased glomerular capillary wall tension, and podocyte dysfunction, which leads to tubulointerstitial fibrosis and loss of nephrons and, finally, chronic kidney disease. The development of new treatments with renal and cardiac effects in the context of type 2 diabetes, which improves mortality outcome, has highlighted the importance of CRS and its prevalence. Increased body fat triggers cellular, neuro-humoral and metabolic pathways, which create a phenotype of the CRS with specific cellular and biochemical biomarkers. Obesity has become a single cardiorenal umbrella or type of cardiorenal metabolic syndrome. This review article provides a clinical overview of the available data on the relationship between a range of adiposity and CRS, the support for obesity as a single cardiorenal umbrella, and the most relevant studies on the recent therapeutic approaches.

[Changes in metabolic parameters and glomerular filtration rate in patients with morbid obesity after bariatric surgery]

AIM

To study the effect of weight loss in the short term after bariatric surgery (BO) on metabolic parameters and glomerular filtration rate (GFR) in patients with morbid obesity.

MATERIALS AND METHODS

We studied 40 adult (over 18 years) patients with morbid obesity who underwent bariatric surgery. Metabolic indices and calculated GFR according to the CKD-EPI formula in patients before and after bariatric surgery were compared.

RESULTS

In the whole group of operated patients, the average body mass index (BMI) after surgery decreased from 45.8 to 30.5 kg/m2. In 11 (92%) patients with impaired carbohydrate metabolism, remission of diabetes mellitus was achieved and sugar-lowering drugs were canceled. In patients with baseline GFR90 ml/min/1.73 m2 after surgery, there is a tendency towards a decrease in GFR, probably due to a decrease in hyperfiltration. In patients with baseline GFR90 ml/min/1.73 m2 after surgery, a statistically significant increase in the level of GFR was noted. The greater metabolic efficacy of combined operations (mini-gastric bypass, biliopancreatic diversion) in relation to the correction of carbohydrate and fat metabolism was revealed.

CONCLUSION

Obesity is a modifiable risk factor for decreased kidney function and the progression of chronic kidney disease. Bariatric surgery is an effective treatment for morbid obesity. The study proved the positive effect of weight loss after BO on renal function, including by improving the course of diseases associated with obesity.

Renal Resistive Index Predicts Post-Bariatric Surgery Renal Outcome in Nondiabetic Individuals with Severe Obesity

OBJECTIVE

Bariatric surgery may ameliorate renal function through vascular mechanisms. This study tested surgery's ability to improve measured glomerular filtration rate (mGFR) and identified clinical, renal, and systemic vascular predictors of such improvement.

METHODS

Twenty-five nondiabetic subjects with severe obesity were studied before and 1 year after Roux-en-Y gastric bypass, evaluating mGFR and renal plasma flow, basal renal resistive index (RI) and dynamic renal RI, renal visceral fat, and systemic vascular parameters, including flow-mediated dilation, aortic pulse wave velocity, and carotid intima media thickness and stiffness.

RESULTS

After Roux-en-Y gastric bypass, BMI decreased by 31%. At follow-up, body surface area (BSA)-adjusted mGFR increased (from 86.9 ± 15.2 to 109.0 ± 18.2 mL/min/1.73 m² , P <  0.001), whereas the absolute mGFR did not change. Renal plasma flow did not vary. RI decreased; flow-mediated dilation, pulse wave velocity, carotid intima media thickness, and carotid stiffness improved. mGFR changes after surgery (ΔmGFR/BSA) were associated with younger age and lower fasting glucose. Among vascular variables, an improved ΔmGFR/BSA was associated with smaller brachial artery diameter, lower intima media thickness, and lower RI; this latter association remained after adjusting for covariates. No measure of adiposity was associated with ΔmGFR.

CONCLUSIONS

In subjects with obesity and normal renal function, bariatric surgery improves mGFR/BSA (although absolute mGFR is unchanged) and renal and systemic vascular function. Lower renal intravascular resistance can predict these improvements, maximizing them in relatively young individuals.

Impact of bariatric surgery in patients with HIV infection: a nationwide inpatient sample analysis, 2004-2014

OBJECTIVE

Despite rising rates of obesity among patients with HIV, the potential role for weight loss surgery in this population remains less clear. The primary aim of this study was to evaluate the role of bariatric surgery on relevant clinical outcomes among hospitalized obese patients with HIV.

DESIGN

Retrospective analysis using the United States Nationwide Inpatient Sample database from 2004 to 2014. Using Poisson regression, adjusted incidence risk ratios (IRR) were derived for clinical outcomes in patients with prior-bariatric surgery compared with those without bariatric surgery.

PATIENTS

Patients with discharge co-diagnoses of morbid obesity and HIV.

INTERVENTION

Bariatric surgery.

MAIN OUTCOME MEASURES

Primary outcome was in-hospital mortality. Secondary outcomes included renal failure, urinary tract infection, malnutrition, sepsis, pneumonia, respiratory failure, thromboembolic events, gastrointestinal strictures, micronutrient deficiency, length of stay, and hospitalization costs.

RESULTS

Among 7803 patients with discharge diagnoses of HIV and morbid obesity, 346 patients (4.4%) had bariatric surgery. The proportion of bariatric surgery in obese patients with HIV initially declined by -0.10% per year from 2004 to 2009 (Ptrend < 0.05), then increased at an annual rate of +0.33% from 2012 to 2014 (Ptrend < 0.05). On multivariable analysis, bariatric surgery did not influence mortality (P = 0.98). Bariatric surgery was associated with decreased risk for renal failure, respiratory failure, and sepsis (all P < 0.001). However, bariatric surgery increased the risk for postoperative strictures (IRR 2.5; 95% CI 1.5-4.5; P = 0.001).

CONCLUSION

Though initially underutilized, bariatric surgery in morbidly obese HIV patients is increasing and appears to be well tolerated and effective in significantly reducing life-threatening morbidity.

Impact of bariatric surgery on outcomes of patients with nonalcoholic fatty liver disease: a nationwide inpatient sample analysis, 2004-2012

BACKGROUND

Bariatric surgery in eligible morbidly obese individuals may improve liver steatosis, inflammation, and fibrosis; however, population-based data on the clinical benefits of bariatric surgery in patients with nonalcoholic fatty liver disease (NAFLD) are lacking.

OBJECTIVES

To assess the relationship between bariatric surgery and clinical outcomes in hospitalized patients with NAFLD.

SETTING

United States inpatient care database.

METHODS

The Nationwide Inpatient Sample database was queried from 2004 to 2012 with co-diagnoses of NAFLD and morbid obesity. Hospitalizations with a history of prior bariatric surgery (Roux-en-Y gastric bypass, gastric band, and sleeve gastrectomy) were also identified. The primary outcome was in-hospital mortality. Secondary outcomes included cirrhosis, myocardial infarction, stroke, and renal failure. Poisson regression was used to derive adjusted incidence risk ratios for clinical outcomes in patients with prior bariatric surgery compared with those without bariatric surgery.

RESULTS

Among 45,462 patients with a discharge diagnosis of NAFLD and morbid obesity, 18,618 patients (41.0%) had prior bariatric surgery. There was a downward trend in bariatric surgery procedures (percent annual change of -5.94% from 2004 to 2012). In a multivariable analysis, prior bariatric surgery was associated with decreased inpatient mortality compared with no bariatric surgery (incidence risk ratios = .08; 95% confidence interval, .03-.20, P<.001). Prior bariatric surgery was also associated with decreased incidence risk ratios for cirrhosis, myocardial infarction, stroke, and renal failure (all P<.001).

CONCLUSIONS

Prior bariatric surgery is associated with decreased in-hospital morbidity and mortality in morbidly obese NAFLD patients. Despite this, the proportion of NAFLD patients with bariatric surgery has declined from 2004 to 2012.