Risk factors for postdischarge venous thromboembolism among bariatric surgery patients and the evolving approach to extended thromboprophylaxis with enoxaparin

Predicting short-term thromboembolic risk following Roux-en-Y gastric bypass using supervised machine learning

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is a widely recognized bariatric procedure that is particularly beneficial for patients with class III obesity. It aids in significant weight loss and improves obesity-related medical conditions. Despite its effectiveness, postoperative care still has challenges. Clinical evidence shows that venous thromboembolism (VTE) is a leading cause of 30-d morbidity and mortality after RYGB. Therefore, a clear unmet need exists for a tailored risk assessment tool for VTE in RYGB candidates.

AIM

To develop and internally validate a scoring system determining the individualized risk of 30-d VTE in patients undergoing RYGB.

METHODS

Using the 2016-2021 Metabolic and Bariatric Surgery Accreditation Quality Improvement Program, data from 6526 patients (body mass index ≥ 40 kg/m2) who underwent RYGB were analyzed. A backward elimination multivariate analysis identified predictors of VTE characterized by pulmonary embolism and/or deep venous thrombosis within 30 d of RYGB. The resultant risk scores were derived from the coefficients of statistically significant variables. The performance of the model was evaluated using receiver operating curves through 5-fold cross-validation.

RESULTS

Of the 26 initial variables, six predictors were identified. These included a history of chronic obstructive pulmonary disease with a regression coefficient (Coef) of 2.54 (P < 0.001), length of stay (Coef 0.08, P < 0.001), prior deep venous thrombosis (Coef 1.61, P < 0.001), hemoglobin A1c > 7% (Coef 1.19, P < 0.001), venous stasis history (Coef 1.43, P < 0.001), and preoperative anticoagulation use (Coef 1.24, P < 0.001). These variables were weighted according to their regression coefficients in an algorithm that was generated for the model predicting 30-d VTE risk post-RYGB. The risk model's area under the curve (AUC) was 0.79 [95% confidence interval (CI): 0.63-0.81], showing good discriminatory power, achieving a sensitivity of 0.60 and a specificity of 0.91. Without training, the same model performed satisfactorily in patients with laparoscopic sleeve gastrectomy with an AUC of 0.63 (95%CI: 0.62-0.64) and endoscopic sleeve gastroplasty with an AUC of 0.76 (95%CI: 0.75-0.78).

CONCLUSION

This simple risk model uses only six variables to assist clinicians in the preoperative risk stratification of RYGB patients, offering insights into factors that heighten the risk of VTE events.

Risk stratified venous thromboembolism prophylaxis in bariatric patients using a Caprini assessment: practice patterns and opportunities for improvement

BACKGROUND

Venous thromboembolism (VTE) is rare after bariatric surgery but is the most common cause of mortality. The use of VTE risk-stratification tools and compliance with practice guidelines remain unclear.

OBJECTIVES

Our objectives were to determine the utilization of risk-stratified VTE prophylaxis and its impact on VTE and bleeding outcomes.

SETTING

Academic hospital system.

METHODS

Roux-en-Y gastric bypass and sleeve gastrectomy (2016-2021) were identified from our electronic health records. Caprini score and VTE prophylaxis regimen were retrospectively determined. VTE prophylaxis consistent with Caprini guidelines was considered appropriate. Outcomes were compared between VTE prophylaxis cohorts. Variables were compared by Kruskal-Wallis test, Pearson χ2 test, and regression models. A P value of <.05 was considered significant.

RESULTS

A total of 1849 bariatric cases were analyzed, including 64% Roux-en-Y gastric bypass and 36% sleeve gastrectomy cases. Of these, 70% and 3.7% received appropriate risk-stratified VTE prophylaxis during hospitalization and at discharge. The mean Caprini score was higher in those without appropriate prophylaxis (8.45 versus 8.04; P = .0004). Inpatient and 30- and 90-day VTE rates were .22%, .47%, and .64%. All discharge VTE events occurred in those not receiving appropriate Caprini risk-stratified VTE prophylaxis. Inpatient and 30- and 90-day bleeding complications were .22%, .23%, and .35%. The likelihood of receiving appropriate prophylaxis varied by hospital site, and receiving appropriate prophylaxis was not associated with increased bleeding risk.

CONCLUSION

Caprini guideline-indicated VTE prophylaxis can be safely used in bariatric surgery patients and may reduce preventable VTE complications without increasing bleeding risk.

Early postoperative COVID infection is associated with significantly increased risk of venous thromboembolism after metabolic and bariatric surgery

BACKGROUND

Patients who undergo metabolic and bariatric surgery (MBS) are at risk for thromboembolism. Patients are susceptible to coronavirus throughout the perioperative period, which also has a well-known association with thrombotic complications.

OBJECTIVES

To identify and define the association between venous thromboembolism (VTE) and postoperative coronavirus diagnosis in bariatric surgery patients.

SETTING

United States.

METHODS

We conducted a retrospective cohort study using the MBS Accreditation and Quality Improvement Program (MBSAQIP) 2021 database to analyze the incidence of VTE within 30 days of surgery. VTE was a composite variable defined as either postoperative pulmonary embolism or postoperative venous thrombus requiring treatment. Cohorts were stratified by whether the patient was diagnosed with postoperative coronavirus. We created a multivariable logistic regression model to determine the adjusted odds of postoperative VTE based on various factors. Additionally, we conducted subset analyses of sleeve gastrectomy and Roux-en-Y bypass cases, the 2 most frequent bariatric operations in the United States.

RESULTS

Patients diagnosed with postoperative coronavirus were significantly more likely to develop postoperative VTE (1.1% versus .3%, P < .001). In our logistic regression model, the adjusted odds of postoperative VTE for patients with postoperative coronavirus was 3.55 (95% CI: 2.15-5.87, P < .001). For patients who underwent Roux-en-Y bypass, the adjusted odds was even greater at 5.69 (95% CI: 2.76-11.70, P < .001).

CONCLUSIONS

Early postoperative coronavirus infection after MBS is associated with higher odds of postoperative VTE. This persisted on subset analyses of the 2 most common procedures and appeared particularly important for Roux-en-Y bypass. COVID infection after MBS may warrant prolonged VTE prophylaxis.

Gender Comparisons of Surgical Outcomes in Patients Undergoing One Anastomosis Gastric Bypass (OAGB): a Historical Cohort Study

INTRODUCTION AND PURPOSE

Clinical trials in the field of bariatrics have frequently been gender imbalanced, with males representing only 20% of examinees. Long-term gender-oriented results in one anastomosis gastric bypass (OAGB), and specifically quality of life (QOL) parameters, have not been addressed sufficiently. A better understanding of gender's effect on OAGB outcomes can play an important role in selecting the appropriate bariatric surgery for patients. Our study was aimed at examining mid-term gender-associated outcome of OAGB, including the effect on QOL.

MATERIALS AND METHODS

A retrospective cohort study of patients who underwent OAGB at surgical ward A, SUMC, Israel, between 2015 and 2020. Demographics, body mass index (BMI), and comorbidities were extracted from the national medical records system. Follow-up quality of life (QOL) and weight parameters were supplemented via telephone questionnaires, using the Bariatric Analysis and Reporting Outcome System (BAROS).

RESULTS

A total of 152 patients were included; of these, 51 (33.6%) were males, with an average follow-up period of 4.1 (± 1.3) years post-surgery. Basic demographics showed no significant pre- or post-surgery differences between males and females, except for pre-op weight (which as expected was higher for males). Males had a higher overall BAROS score than females (3.8 ± 2.1 vs. 2.6 ± 2.1, p < 0.001).

CONCLUSIONS

OAGB surgery results in better outcomes for male than for female patients as measured by the BAROS, despite a similar BMI reduction, and with no difference in complications. Gender-specific outcomes are one of the variables that one should be aware of in optimizing patient selection and pre-operative patient counseling.

Portomesenteric Vein Thrombosis in Patients Undergoing Sleeve Gastrectomy: an Updated Systematic Review and Meta-Analysis of 101,914 Patients

INTRODUCTION

Portomesenteric vein thrombosis (PMVT) is a rare but potentially fatal complication of sleeve gastrectomy (SG). The rising prevalence of SG has led to a surge in the occurrence of PMVT, while the associated risk factors have not been fully elucidated. This study aims to determine the incidence and risk factors of PMVT in patients undergoing SG.

METHODS

A comprehensive literature search was performed in PubMed and EMBASE databases. Proportion and regression meta-analyses were conducted.

RESULTS

In a total of 76 studies including 101,914 patients undergoing SG, we identified 357 patients with PMVT. Mean follow-up was 14.4 (SD: 16.3) months. The incidence of PMVT was found to be 0.50% (95%CI: 0.40-0.61%). The majority of the population presented with abdominal pain (91.8%) at an average of 22.4 days postoperatively and PMVT was mainly diagnosed with computed tomography (CT) (96.0%). Hematologic abnormalities predisposing to thrombophilia were identified in 34.9% of the population. Advanced age (p=0.02) and low center volume (p <0.0001) were significantly associated with PMVT, while gender, BMI, hematologic abnormality, prior history of deep vein thrombosis or pulmonary embolism, type of prophylactic anticoagulation, and duration of prophylactic anticoagulation were not associated with the incidence of PMVT in meta-regression analyses. Treatment included therapeutic anticoagulation in 93.4% and the mortality rate was 4/357 (1.1%).

CONCLUSION

PMVT is a rare complication of sleeve gastrectomy with an incidence rate <1% that is associated with low center volume and advanced age but is not affected by the duration or type of thromboprophylaxis administered postoperatively.

Effectiveness of Body Mass Index-Based Prophylactic Enoxaparin Dosing in Bariatric Surgery Patients

INTRODUCTION

Enoxaparin is administered for venous thromboembolic (VTE) prophylaxis in bariatric surgery patients. There is concern whether body mass index (BMI)-based enoxaparin dosing consistently achieves prophylactic targets in patients with severe obesity.

METHODS

This retrospective study included patients who underwent bariatric surgery at an academic medical center from Jan 2015-May 2021 and had an anti-Xa level drawn 2.5-6 h after ≥3 doses of BMI-based prophylactic enoxaparin. The primary outcome was the percentage of patients who achieved a target anti-Xa level. Secondary outcomes were prevalence of venous thromboembolic and bleeding events within 30 d post-operatively.

RESULTS

Overall, 137 patients were included. Mean BMI was 59.1 ± 10.4 kg/m², mean age was 43.9 ± 13.3 y and 110 patients (80.3%) were female. Target anti-Xa levels were achieved in 116 patients (84.7%); 14 (10.2%) were above target and 7 (5.1%) were below target. Patients with above target anti-Xa levels were significantly shorter in height than those within target range (167.1 versus 159.8 cm, P = 0.003). Five patients (3.6%) had a bleeding event; no thromboembolisms occurred. Anti-Xa levels correlated more strongly with enoxaparin dose per unit estimated blood volume (EBV) than dose per unit BMI (Rho = 0.54 versus Rho = 0.33).

CONCLUSIONS

Target range anti-Xa levels were achieved in 85% of patients using BMI-based enoxaparin dosing. Patients with above target anti-Xa levels were significantly shorter by nearly 3 inches, suggesting an increased risk of overdosing enoxaparin in shorter, obese patients. An EBV-based dosing regimen may better account for patient height and is supported by a greater correlation with anti-Xa levels with dosing based on EBV than BMI.

The use of enoxaparin as venous thromboembolism prophylaxis in bariatric surgery: A retrospective cohort study

Introduction

Venous thromboembolism (VTE) is one of the major causes of morbidity and mortality in bariatric patients. The use of low-molecular-weight heparin (LMWH), as enoxaparin, is considered one of the mainstays thromboprophylaxis regimens in postoperative bariatric patients. Despite the universal agreement on the importance of thromboprophylaxis in these patients, there are inadequate strong recommendations for its dosing and duration. The aim of our study is to explore the current practice on using enoxaparin in bariatric patients, as well as to assess both the efficacy and safety of varying dosing regimens.

Material and methods

This is a retrospective cohort study of morbidly obese patients who underwent bariatric procedure at a tertiary care hospital between 2016 and 2019. All adult patients who met the eligibility criteria for bariatric surgery and received enoxaparin with a minimum follow-up period of one month were included in our study. Participants with a history of coagulopathy, renal or hepatic insufficiency were excluded from the study. Data collected include patient demographics, VTE risk factors, and co-morbidities. The outcome of treatment failure was defined as the composite of either VTE or major bleeding.

Results

A total of 1,169 patients who underwent bariatric surgery were included in the study. The mean age was 35.54 years, with mean body mass index (BMI) of 45.78 kg/m². The mean duration of enoxaparin use was 9 days, and the majority of patients (78%) received a prophylaxis dose of 40 mg subcutaneously (SC) once daily. The overall rate of VTE at 90 days was 1.4% while only 0.1% of patients developed major bleeding. There was no statistically significant difference in patients’ age, gender, BMI, or various enoxaparin dosing regimens between patients who developed VTE or bleeding versus patients who did not develop. Patient’s weight was the only statistically significant risk factor that directly correlated to higher risk of complications (P = 0.006). In the multivariable logistic regression model, higher BMI was significantly associated with treatment failure, either VTE or major bleeding [OR 1.05 (95% CI 1.0–1.09); P = 0.038].

Conclusions

The rate of VTE or major bleeding did not differ in patients who received various enoxaparin regimens. Patients undergoing bariatric surgery may benefit from enoxaparin thromboprophylaxis dose of 40 mg SC daily for a total duration of 14 days, with higher doses may be needed for extremely obese patients. We recommend standardizing the current practice of VTE prophylaxis post bariatric surgery and unifying the optimal dose and duration.

Five-Year Analysis of the MBSAQIP Database: Are We Getting Better?

BACKGROUND

The MBSAQIP has been used to evaluate risk and create risk models. Previous studies have determined what complications matter most.

STUDY DESIGN

This study was a registry-based analysis of patients who underwent laparoscopic Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) between January 1, 2015, and December 31, 2019, at centers participating in MBSAQIP. Cases were identified using Current Procedural Terminology. Patients less than 18 years old were excluded. A chi-square test was used to assess differences in the prevalence of complications and effects across years. Using a multivariable Poisson regression model with a link log and robust estimation, prevalence ratio estimates and 95% CI were obtained.

RESULTS

A total of 690,770 observations met the inclusion criteria. Mean (SD) age was 44.5 (±12.0) years, and mean (SD) BMI was 45.2 kg/m2 (±7.9). SG cases accounted for 73.45% of all observations. There was a significant relative reduction in readmissions, end-organ dysfunction, and all-cause mortality from 2015 to 2019 in the SG subgroup. There were also noticeable reductions in 30-day readmission, ICU admission, and end-organ dysfunction in the RYGB subgroup. For complications, bleeding, postoperative pneumonia, and stroke were significantly decreased in the RYGB subgroup, but only bleeding was significantly decreased in the SG subgroup during the 5-year study period.

CONCLUSIONS

There has been a continuous improvement in several (but not all) outcomes through the years that the MBSAQIP has been collecting data. Different outcomes were reduced between the SG and RYGB subgroups, and the decrease in all-cause mortality was only noted in the SG subgroup.