Roux-en-Y gastric bypass compared with aggressive diet and exercise therapy for morbidly obese patients awaiting renal transplant: a decision analysis

A Scoping Review of Artificial Intelligence and Machine Learning in Bariatric and Metabolic Surgery: Current Status and Future Perspectives

Artificial intelligence (AI) is a revolution in data analysis with emerging roles in various specialties and with various applications. The objective of this scoping review was to retrieve current literature on the fields of AI that have been applied to metabolic bariatric surgery (MBS) and to investigate potential applications of AI as a decision-making tool of the bariatric surgeon. Initial search yielded 3260 studies published from January 2000 until March 2021. After screening, 49 unique articles were included in the final analysis. Studies were grouped into categories, and the frequency of appearing algorithms, dataset types, and metrics were documented. The heterogeneity of current studies showed that meticulous validation, strict reporting systems, and reliable benchmarking are mandatory for ensuring the clinical validity of future research.

Bariatric Surgery for Congestive Heart Failure Patients Improves Access to Transplantation and Long-term Survival

INTRODUCTION

Obese patients with congestive heart failure (CHF) are often denied access to heart transplantation until they obtain significant weight loss to achieve a certain BMI threshold, often less than 35 kg/m². It is unknown whether the rapid weight loss associated with bariatric surgery leads to improved waitlist placement, and as such improved survival for morbidly obese patients with CHF.

METHODS

A decision analytic Markov state transition model was created to simulate the life of morbidly obese patients with CHF who were deemed ineligible to be waitlisted for heart transplantation unless they achieved a BMI less than 35 kg/m². Life expectancy following medical weight management (MWM), Roux-en-Y gastric bypass (RYGB), and sleeve gastrectomy (SG) was estimated. Base case patients were defined as having a pre-intervention BMI of 45 kg/m². Sensitivity analysis of initial BMI was performed. Markov parameters were extracted from literature review.

RESULTS

RYGB improved survival compared with both SG and MWM. RYGB patients had higher rates of transplantation, leading to improved mean long-term survival. Base case patients who underwent RYGB gained 2.1 additional years of life compared with patient's who underwent SG and 7.4 additional years of life compared with MWM. SG patients gained 5.3 years of life compared with MWM.

CONCLUSIONS

When strict waitlist criteria were applied, bariatric surgery improved access to heart transplantation and thereby increased long-term survival compared with MWM. Morbidly obese CHF patients who anticipate need for heart transplantation should be encouraged to pursue surgical weight management strategies, necessitating discussion between bariatric surgeons, cardiologists, and cardiac surgeons for appropriate perioperative risk management.

STEP improves long-term survival for pediatric short bowel syndrome patients: A Markov decision analysis

INTRODUCTION

Increasingly, for pediatric patients with short bowel syndrome (SBS), intestinal lengthening procedures such as serial transverse enteroplasty (STEP) are being offered with the hope of improving patients' chances for achieving enteral autonomy. However, it remains unclear to what extent STEP reduces the long-term need for intestinal transplant or improves survival.

METHODS

Based on existing literature, a decision analytic Markov state transition model was created to simulate the life of 1,000 pediatric SBS patients. Two simulations were modeled: 1) No STEP: patients were listed for transplant once medical management failed and 2) STEP: patients underwent STEP therapy and subsequent transplant listing if enteral autonomy was not achieved. Sensitivity analysis of small bowel length and anatomy was completed. Base case patients were defined as neonates with a small bowel length of 30cm.

RESULTS

For base case patients with an ostomy and a NEC SBS etiology, STEP was associated with increased rates of enteral autonomy after 10 years for patients with an ICV (53.9% [STEP] vs. 51.1% [No STEP]) and without an ICV (43.4% [STEP] vs. 36.3% [No STEP]). Transplantation rates were also reduced following STEP therapy for both ICV (17.5% [STEP] vs. 18.2% [No STEP]) and non-ICV patients (20.2% [STEP] vs. 22.1% [No STEP]). 10-year survival was the highest in the (+) STEP and (+) ICV group (85.4%) and lowest in the (-) STEP and (-) ICV group (83.3%).

CONCLUSIONS

For SBS patients, according to our model, STEP increases rates of enteral autonomy, reduces need for intestinal transplantation, and improves long-term survival.

TYPE OF STUDY

Economic/Decision Analysis or Modeling Studies LEVEL OF EVIDENCE: Level III.

Salvage use of tissue plasminogen activator (tPA) in the setting of acute respiratory distress syndrome (ARDS) due to COVID-19 in the USA: a Markov decision analysis

Background

COVID-19 threatens to quickly overwhelm our existing critical care infrastructure in the USA. Systemic tissue plasminogen activator (tPA) has been previously demonstrated to improve PaO₂/FiO₂ (mmHg) when given to critically ill patients with acute respiratory distress syndrome (ARDS). It is unclear to what extent tPA may impact population-based survival during the current US COVID-19 pandemic.

Methods

A decision analytic Markov state transition model was created to simulate the life critically ill COVID-19 patients as they transitioned to either recovery or death. Two patient groups were simulated (50,000 patients in each group); (1) Patients received tPA immediately upon diagnosis of ARDS and (2) patients received standard therapy for ARDS. Base case critically ill COVID-19 patients were defined as having a refractory PaO₂/FiO₂ of < 60 mmHg (salvage use criteria). Transition from severe to moderate to mild ARDS, recovery, and death were estimated. Markov model parameters were extracted from existing ARDS/COVID-19 literature.

Results

The use of tPA was associated with reduced mortality (47.6% [tTPA] vs. 71.0% [no tPA]) for base case patients. When extrapolated to the projected COVID-19 eligible for salvage use tPA in the USA, peak mortality (deaths/100,000 patients) was reduced for both optimal social distancing (70.5 [tPA] vs. 75.0 [no tPA]) and no social distancing (158.7 [tPA] vs. 168.8 [no tPA]) scenarios.

Conclusions

Salvage use of tPA may improve recovery of ARDS patients, thereby reducing COVID-19-related mortality and ensuring sufficient resources to manage this pandemic.

Uncontrolled donation after circulatory death improves access to kidney transplantation: A decision analysis

AIM

Uncontrolled donation after cardiac death (uDCD) remains an underutilized source of kidney allografts in the United States. The objective of this study was to estimate the impact of the implementation of a uDCD program on transplantation rates and long-term survival for patients with end-stage renal disease (ESRD) in the United States.

METHODS

A decision-analytic Markov state transition model was created using medical decision-making software (DATA 3.5; TreeAge Software, Inc) to estimate the impact of an uDCD program on transplantation rates and patient survival. Additionally, sensitivity analysis of uDCD donor pool increase was modeled. All model statistic parameters were extracted from the literature.

RESULTS

A uDCD program increased the rate of transplant at 10 years (37.8%, Accept uDCD group, vs 35.9%, Reject uDCD group). At 10 years, overall survival for Accept uDCD was 55.6% compared to 54.8% in the Reject uDCD.

CONCLUSIONS

Uncontrolled DCD improves access to transplant for ESRD patients on the kidney transplant waitlist, thereby improving long-term survival.

Sleeve Gastrectomy Compared with Gastric Bypass for Morbidly Obese Patients with End Stage Renal Disease: a Decision Analysis

INTRODUCTION

The use of bariatric surgery has increased for morbidly obese patients with end stage renal disease (ESRD) for whom listing on the waitlist is often restricted until a certain BMI threshold is achieved. Effective weight loss for this population improves access to life-saving renal transplantation. However, it is unclear whether sleeve gastrectomy (SG) vs Roux-en-Y gastric bypass (RYGB) is a more effective therapy for these patients.

METHODS

A decision analytic Markov state transition model was created to simulate the life of morbidly obese patients with ESRD who were deemed ineligible to be waitlisted for renal transplantation unless they achieved a BMI less than 35 kg/m². Life expectancy following weight management (MWM), RYGB, and SG were estimated. Base case patients were defined as having a pre-intervention BMI of 45 kg/m². Sensitivity analysis of initial BMI was performed. Markov parameters were extracted from literature review.

RESULTS

RYGB improved survival compared with SG and MWM. RYGB patients had higher rates of transplantation, leading to improved mean long-term survival. Base case patients who underwent RYGB gained 1.3 additional years of life compared with patient's who underwent SG and 2.6 additional years of life compared with MWM.

CONCLUSIONS

RYGB improves access to renal transplantation and thereby increases long-term survival compared with SG and MWM. The use of SG may be incongruent with the goal of improving access to renal transplantation for morbidly obese patients.

Roux-en-Y gastric bypass is an effective bridge to kidney transplantation: Results from a single center

Body mass index (BMI) > 35-40 kg/m² is often a contraindication, while Roux-en-Y gastric bypass (RYGB) is performed to enable kidney transplantation. This single-center retrospective study evaluated pre- and post-transplant outcomes of 31 morbidly obese patients with end-stage renal disease having RYGB before kidney transplantation between July 2009 and June 2014. Fourteen RYGB patients were subsequently transplanted. Nineteen recipients not having GB with a BMI ≥ 36 kg/m² at transplantation were used as historical controls. Mean BMI (±SE) before RYGB was 43.5 ± 0.7 kg/m² (range: 35.4-50.5 kg/m² ); 87.1% (27/31) achieved a BMI < 35 kg/m² . The percentage having improved diabetes/hypertension control was 29.0% (9/31); 25.8% (8/31) had complications (mostly minor) after RYGB. Among transplanted patients, blacks/Hispanics comprised 78.6% (11/14) and 84.2% (16/19) of RYGB and controls; 57.1% (8/14) and 63.2% (12/19) had a (mostly long-standing) pretransplant history of diabetes. While biopsy-proven acute rejection (BPAR) occurred significantly higher among RYGB vs control patients (6/14 vs 3/19, P = .03), patients developing T-cell BPAR were also significantly more likely to have a tacrolimus (TAC) trough level < 4.0 ng/mL within 3 weeks of T-cell BPAR (P = .0007). In Cox's model, the impact of having a TAC level < 4.0 ng/mg remained significant (P = .007) while the effect of RYGB was no longer significant (P = .13). Infections, graft, and patient survival were not significantly different. Despite obvious effectiveness in achieving weight loss, RYGB will need more careful post-transplant monitoring given the observed higher BPAR rate.

Bariatric Surgery in Renal Transplant Patients

OBJECTIVES

The idea of transplanting organs is not new, nor is the disease of obesity. Obese transplant recipients have greater risk of early death than their cohorts, which is not due to increased rejection but due to obesity-related complications, including arterial hypertension, diabetes, and delayed graft function. Here, our aim was to evaluate the effects of bariatric surgery versus lifestyle changes on outcomes of moderate to severely obese renal transplant recipients.

MATERIALS AND METHODS

Twenty-two morbidly obese patients with stable graft function who underwent bariatric surgery were compared with 44 obese patients on lifestyle management (control group). Both groups were evaluated regarding graft and patient outcomes.

RESULTS

The studied groups were comparable demographically. In the bariatric study group versus control group, we observed that the mean body mass index was 38.49 ± 9.1 versus 44.24 ± 6 (P = .024) at transplant and 34.34 ± 7.6 versus 44.38 ± 6.7 (P = .002) at 6 months of bariatric surgery. Both groups received a more potent induction immunosuppression, but this was significantly higher in the obese nonbariatric control group (P < .05). There were more patients with slow and delayed graft functions in the same nonbariatric group. The 2 groups were comparable regarding new-onset diabetes after transplant, total patients with diabetes, and graft outcomes (P > .05).

CONCLUSIONS

Bariatric surgeries are feasible, safe pro cedures for selected obese renal transplant recipients.

Bariatric Surgery in Patients with Dialysis-Dependent Renal Failure

BACKGROUND

Laparoscopic procedures for the treatment of morbid obesity are commonly offered to patients with comorbidities previously thought to carry prohibitive operative risk. In this study, we reviewed characteristics and perioperative outcomes of patients with dialysis-dependent renal failure (DDRF) who underwent laparoscopic bariatric procedures.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2006 to 2011 was reviewed. Preoperative characteristics and 30-day outcome data of patients who underwent three common laparoscopic procedures were analyzed using ANOVA and Pearson chi-squared tests.

RESULTS

One hundred thirty-eight patients (52.5 % female) with DDRF and a median body mass index (BMI) of 45.5 kg/m(2) were identified; 33.8 % (n = 47) underwent laparoscopic banding (LAGB), 48.9 % (n = 68) laparoscopic Roux-en-Y gastric bypass (RYGB), and 16.5 % (n = 23) laparoscopic sleeve gastrectomy (LSG). No differences were found among groups in age, prevalence of American Society of Anesthesiology IV classification, BMI, weight, gender, prevalence of diabetes, and vascular or neurologic comorbidities. Total operation time and length of hospital stay were significantly different between groups. Mortality was 0.7 %, and overall morbidity was 5.8 %. The case mix reflected a decrease in LAGB procedures from 45.5 to 23.3 % from 2006-2009 to 2010-2011 and an increase in LSG procedures from 9.1 to 24.7 % (p < 0.006).

CONCLUSIONS

When performed in selected DDRF patients, bariatric surgery is safe. An increase in LSG with a concurrent decline in LAGB procedures was demonstrated over the period of the study.

Re-examining the BMI threshold for bariatric surgery in the USA

BACKGROUND

The optimal BMI threshold above which gastric bypass surgery should be offered to obese patients is controversial. The objective of this study was to compare the impact of Roux-en-Y gastric bypass (RYGB) vs. diet and exercise (D&E) on life expectancy to find the BMI at which patients experience an improvement in their life expectancy by undergoing surgery.

METHODS

A Markov state transition model was designed to implement a decision tree that simulated the lives of obese patients. Life expectancies following RYGB and 2 years of D&E were estimated and compared. Ten thousand patients' lives were simulated in each weight-loss intervention group in the model. In addition to base case analysis (45 kg/m(2) BMI pre-intervention), sensitivity analysis of initial BMI at the start of the study was completed. Markov model parameters were extracted from the literature.

RESULTS

The impact of RYGB on survival relative to D&E depended on the patient's initial BMI. Compared to patients who underwent 2 years of "optimal" diet and exercise (7 % total body weight loss/year), RYGB improved long-term survival for patients above a BMI of 31.3 kg/m(2).

CONCLUSIONS

Roux-en-Y gastric bypass can improve long-term survival for patients with class I obesity. This study suggests that RYGB should not be reserved solely for patients with class II or III obesity.