Weight loss interventions for morbidly obese patients with compensated cirrhosis: a Markov decision analysis model

Ventricular Remodeling Following Metabolic and Bariatric Surgery Decreases Need for Heart Transplantation: A Predictive Model

PURPOSE

For patients with obesity and congestive heart failure (CHF) who require heart transplantation (HT), aggressive weight loss has been associated with ventricular remodeling, or subclinical alterations in left and right ventricular structure that affect systolic function. Many have suggested offering metabolic and bariatric surgery (MBS) for these patients. As such, we evaluated the role of MBS in HT for patients with obesity and CHF using predictive modelling techniques.

MATERIALS AND METHODS

Markov decision analysis was performed to simulate the life expectancy of 30,000 patients with concomitant obesity, CHF, and 30% ejection fraction (EF) who were deemed ineligible to be waitlisted for HT unless they achieved a BMI < 35 kg/m2. Life expectancy following diet and exercise (DE), 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.

RESULTS

RYGB patients had lower rates of HT and received HT quicker when needed. Base case patients who underwent RYGB gained 2.2 additional mean years survival compared with patients who underwent SG and 10.3 additional mean years survival compared with DE. SG patients gained 6.2 mean years of life compared with DE.

CONCLUSION

In this simulation of 30,000 patients with obesity, CHF, and reduced EF, MBS was associated with improved survival by not only decreasing the need for transplantation due to improvements in EF, but also increasing access to HT when needed due to lower average BMI.

Exploratory Approach to Incorporating Carbon Footprint in Health Technology Assessment (HTA) Modelling: Cost-Effectiveness Analysis of Health Interventions in the United Kingdom

BACKGROUND

Health interventions contribute to the production of greenhouse gas emissions. Thus, reducing carbon footprint is essential in supporting the UK National Health Service (NHS) pathway to net zero. This study explores the approach in which carbon footprint can be included when applying Health Technology Assessment (HTA) modelling using obesity intervention in the United Kingdom (UK) as a case study.

METHODS

Using decision analytic modelling, we conducted an HTA incorporating the impacts of obesity-related treatment decisions on UK carbon emissions. A cohort Markov model was used to track the emissions of the UK population after receiving one of two obesity treatments: semaglutide and bariatric surgery.

RESULTS

This study introduced two new carbon measurement tools that may be useful for future policymaking, incremental carbon footprint effectiveness ratio (ICFER) and incremental carbon footprint cost ratio (ICFCR), which made it possible to assess the emission impacts of proposed health policies. Using the obesity intervention case study, we found that both treatments have an incremental cost-effectiveness ratio (ICER) of < £20,000 per quality-adjusted life-years (QALYs) gained. This is below the UK threshold, indicating that these are cost-effective treatments for obesity, but could increase the NHS carbon footprint. However, it could reduce the overall UK societal carbon footprint by reducing the number of people with obesity. The ICFCR shows a reduction of 1.13-4.51 kgCO2e (kilogram of carbon dioxide equivalent) for every pound spent on obesity treatment.

CONCLUSION

This study illustrates a case study for estimating the effect of health policies on carbon emissions and provides a quantitative measure for obesity-related treatment decisions.

Outcomes of Bariatric Surgery in Patients with Liver Cirrhosis: a Systematic Review

Obesity is commonly associated with non-alcoholic fatty liver disease and is a significant cause of chronic liver disease and cirrhosis. Some patients undergoing bariatric surgery suffer from cirrhosis of the liver. Currently, there is a lack of consensus on the management of these patients and the safety and efficacy of bariatric surgery in this group. This review aims to update our previously published systematic review on the same topic. A total of 21 studies reporting experience on patients with cirrhosis undergoing bariatric surgery were included. Sleeve gastrectomy was the most common surgery performed, followed by Roux-en-Y gastric bypass. The results show that bariatric surgery may be feasible in carefully selected patients with obesity and cirrhosis although they have slightly higher morbidity and mortality rates.

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.

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.

Cost-effectiveness Analysis of Bariatric Surgery for Patients With Nonalcoholic Steatohepatitis Cirrhosis

IMPORTANCE

Obesity is the most common risk factor for nonalcoholic steatohepatitis (NASH), the progressive form of nonalcoholic fatty liver disease that can lead to cirrhosis and hepatocellular carcinoma. Weight loss can be an effective treatment for obesity and may slow the progression of advanced liver disease.

OBJECTIVE

To assess the cost-effectiveness of bariatric surgery in patients with NASH and compensated cirrhosis.

DESIGN, SETTING, AND PARTICIPANTS

This economic evaluation study used a Markov-based state-transition model to simulate the benefits and risks of laparoscopic sleeve gastrectomy (SG), laparoscopic Roux-en-Y gastric bypass (GB), and intensive lifestyle intervention (ILI) compared with usual care in patients with NASH and compensated cirrhosis and varying baseline weight (overweight, mild obesity, moderate obesity, and severe obesity). Patients faced varied risks of perioperative mortality and complications depending on the type of surgery they underwent. Data were collected on March 22, 2017.

MAIN OUTCOMES AND MEASURES

Life-years, quality-adjusted life-years (QALYs), costs (in 2017 $US), and incremental cost-effectiveness ratios (ICERs) were calculated.

RESULTS

Demographic characteristics of the patient population were based on a previously published prospective study (n = 161). Patients in the model were 41.0% female, and the base case age was 54 years. Compared with usual care, SG was associated with an increase in QALYs of 0.263 to 1.180 (bounds of ranges represent overweight to severe obesity); GB, 0.263 to 1.207; and ILI, 0.004 to 0.216. Sleeve gastrectomy was also associated with an increase in life-years of 0.693 to 1.930; GB, 0.694 to 1.947; and ILI, 0.012 to 0.114. With usual care, expected life-years in overweight, mild obesity, moderate obesity, and severe obesity were 12.939, 11.949, 10.976, and 10.095, respectively. With usual care, QALY in overweight was 6.418; mild obesity, 5.790; moderate obesity, 5.186; and severe obesity, 4.577. Sleeve gastrectomy was the most cost-effective option for patients across all weight classes assessed: ICER for SG in patients with overweight was $66 119 per QALY; mild obesity, $18 716 per QALY; moderate obesity, $10 274 per QALY; and severe obesity, $6563 per QALY. A threshold analysis on the procedure cost of GB found that for GB to be cost-effective, the cost of the surgery must be decreased from its baseline value of $28 734 by $4889 for mild obesity, by $3189 for moderate obesity, and by $2289 for severe obesity. In overweight patients, GB involved fewer QALYs than SG, and thus decreasing the cost of surgery would not result in cost-effectiveness.

CONCLUSIONS AND RELEVANCE

Bariatric surgery could be highly cost-effective in patients with NASH compensated cirrhosis and obesity or overweight. The findings from this analysis suggest that it can inform clinical trials evaluating the effect of bariatric procedures in patients with NASH cirrhosis, including those with a lower body mass index.

Bariatric surgery for nonalcoholic steatohepatitis: A clinical and cost-effectiveness analysis

Nonalcoholic steatohepatitis (NASH) affects 2%-3% of the US population and is expected to become the leading indication for liver transplantation in the next decade. Bariatric surgery may be an effective but expensive treatment for NASH. Using a state-transition model, our analysis assessed the effectiveness and cost-effectiveness of surgery to manage NASH. We simulated the benefits and harms of laparoscopic Roux-en-Y gastric bypass surgery in patients defined by weight class (overweight, mild obesity, moderate obesity, and severe obesity) and fibrosis stage (F0-F3). Comparators included intensive lifestyle intervention (ILI) and no treatment. Quality-adjusted life years (QALYs), costs, and incremental cost-effectiveness ratios were calculated. Our results showed that surgery and ILI in obese patients (with F0-F3) increased QALYs by 0.678-2.152 and 0.452-0.618, respectively, compared with no treatment. Incremental cost-effectiveness ratios for surgery in all F0-F3 patients with mild, moderate, or severe obesity were $48,836/QALY, $24,949/QALY, and $19,222/QALY, respectively. In overweight patients (with F0-F3), surgery increased QALYs by 0.050-0.824 and ILI increased QALYs by 0.031-0.164. In overweight patients, it was cost-effective to reserve treatment only for F3 patients; the incremental cost-effectiveness ratios for providing surgery or ILI only to F3 patients were $30,484/QALY and $25,367/QALY, respectively.

CONCLUSIONS

Surgery was both effective and cost-effective for obese patients with NASH, regardless of fibrosis stage; in overweight patients, surgery increased QALYs for all patients regardless of fibrosis stage, but was cost-effective only for patients with F3 fibrosis; our results highlight the promise of bariatric surgery for treating NASH and underscore the need for clinical trials in this area. (Hepatology 2017;65:1156-1164).

A Systematic Review of Bariatric Surgery in Patients with Liver Cirrhosis

Nonalcoholic steatohepatitis is becoming a common cause of liver cirrhosis and a significant number of patients undergoing bariatric surgery suffer with it. There is currently lack of consensus among surgeons regarding safety of bariatric surgery in patients with liver cirrhosis and the best bariatric procedure in these patients. This review investigates published English language scientific literature systematically in an attempt to answer these questions. Eleven studies that reported experience of bariatric surgery in cirrhotic obese patients were included in this review. This review shows an acceptably higher overall risk of complications and perioperative mortality with bariatric surgery in cirrhotic patients. Surgeons must discuss the possibility of an unexpected intraoperative diagnosis of cirrhosis preoperatively with all bariatric surgery patients and agree on a course of action.

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.