United States

Background: Children with inflammatory bowel disease (IBD) are at risk of venous thromboembolic events (VTE). The efficacy of low molecular-weight heparin (LMWH) in preventing VTE in pediatrics is undetermined, but it is used for VTE prophylaxis. We offered prophylaxis to high-risk inpatients based on risk-stratification. We aimed to assess the efficacy of prophylactic LMWH in preventing VTE in high-risk pediatric IBD inpatients.

Methods: We performed a retrospective chart review at Seattle Children’s Hospital from 2012–2021. We included IBD patients aged 0-18 hospitalized with colitis flares. Patients admitted for surgery, perianal abscess, or non-IBD colitis were excluded. VTE risk factors were personal or family history of VTE, thrombophilia, thrombogenic medication use, smoking, obesity, or central venous line (CVL). Serious events were pulmonary embolus, stroke, or cerebral sinus venous thrombosis. The index case, first admission during the study period or with VTE, was used for analysis.

Results: 415 patients were included. Mean age was 13 ± 4, with 52.8% male. 239 (57.6%) had Crohn’s disease and 170 (41.0%) ulcerative colitis. Common risk factors were CVL (45, 10.8%) and obesity (19, 4.6%). 25 patients received prophylaxis (6.0%). There were 10 VTE events (2.4%), 3/25 (12.0%) in patients on LMWH and 7/383 (1.8%) without. There was one serious event of left middle cerebral artery thrombus and stroke in a patient not on LMWH with no risk factors. There were no serious events in patients on LMWH. The incidence of VTE was significantly higher in patients on LWMH (p=0.001, 95% CI 0.039-0.165) with RR 6.7 (p=0.0039, 95% CI 1.84-24.3). Of the 7 VTE in patients not on prophylaxis, 3 occurred in patients with no risk factors, 2 in patients with 1 risk factor, and 2 in patients with 2 risk factors.

Conclusion: Prophylactic LMWH did not prevent VTE in high-risk pediatric IBD patients. However, our population at a tertiary hospital may be sicker than the baseline. An alternative prophylaxis regimen may be needed for high-risk patients. Further data is required to identify other risk factors for VTE, and randomized control trials are needed to establish the true efficacy of LMWH in this population.

2022 AMA Research Challenge

Prophylactic enoxaparin fails to prevent thrombosis in high-risk pediatric inflammatory bowel disease

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Charles Lopresto, DO

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poster

Background: COVID-19 has been accompanied by a 34% increase in revenue from the sale of alcohol largely attributed to young adults, households with children, and minority groups. From 2007-2014 hospitalizations due to alcoholic hepatitis and cirrhosis increased. As alcoholic liver disease is the leading cause for liver transplant in the U.S. and nearly 50% of liver related deaths, it is vital to better understand the pathophysiology of alcoholic cirrhosis and to identify biomarkers that predict which patients will progress to fibrosis.

Methods: Subjects were recruited with alcoholic cirrhosis at stage F4 of fibrosis (n = 11) and heavy drinkers without cirrhosis at stages F0-F3 of fibrosis (n = 11). Fibrosis was assessed by elastography, and alcohol consumption with the Alcoholic Use Disorders Identification Test-Concise (AUDIT-C) questionnaire. Untargeted LC-MS was performed on serum by Metabolon. Significance was assessed by Welch’s two sample t-test.

Results: There were no differences in age, gender, BMI, or AUDIT-C scores. Overall, 122 metabolites were upregulated and 127 downregulated in subjects with scores of F4 versus F0-F3. Pathway analysis revealed diacylgycerols, androgenic steroids, dihydroceramides, and glutathione metabolites were increased in non-cirrhotic subjects, while cirrhotic subjects showed increases in sterol metabolism, hemoglobin and porphyrin metabolism, and bile acid (primary and secondary) metabolism. Additionally, thymine and uracil pyrimidine metabolism were upregulated in cirrhotic subjects (F4), uncovering novel pathways for future biomarker studies. Specifically, cirrhotic subjects demonstrated increases in abundance of 5,6-dihydrothymine, 2’-O-methyluridine, 3-ureidopropionate, 5,6-dihydrouracil, and uracil. With respect to tryptophan metabolites, our analysis showed significant upregulation in circulating levels of kynurenine, oxindolylalanine, tryptophan, as well as significant decreases in 3-indoxyl sulfate, serotonin, and xanthurenate in F4 subjects compared to F0-F3. The suggests an increase in IDO-1 activity during cirrhosis, shunting tryptophan away from serotonin synthesis towards kynurenine. We also identified metabolites with significant associations with fibrosis score such as 5,6-dihydrothymine (r = 0.88), taurochenodeoxycholic acid 3-sulfate (r = 0.84), leucine (r = -0.8), and retinol (r = -0.8)

Conclusion: Our findings elucidate metabolic alterations in alcoholic liver fibrosis with the identification of several pyrimidine and tryptophan metabolites that may be used for the assessment of alcoholic liver disease.

Serum Metabolome of Alcoholic Cirrhosis Patients Reveal Changes in Pyrimidine and Tryptophan Metabolites

We present the rare case of a 40-year-old male who was found to have a scrotal leiomyoma. Leiomyomas are benign tumors of smooth muscles. Very rarely, they can affect the smooth muscle layers of the scrotum (dartos and cremasters). In a review of 11,0000 scrotal tumors, only 11 cases were found to be leiomyomas.

A Leiomyoma Presenting as an Enlarging Scrotal Mass in a 40-year-old Male

Background
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination elicits a variable, often suboptimal immune response among solid organ transplant recipients (SOTRs), who are at increased risk of severe COVID-19 compared to immunocompetent individuals. An accurate prediction model for lack of immune response to SARS-CoV-2 vaccination could provide for a more tailored approach to antibody testing, risk stratification, and clinical decision making. The objective was to create a prediction model for failure to generate an antibody response to threedose
SARS-CoV-2 vaccination in SOTRs.
Methods
782 thrice-vaccinated COVID-naïve SOTRs were recruited for this national prospective observational study. Participants underwent serologic antibody testing (Roche Elecsys antireceptor binding domain [RBD] or Euroimmun anti-spike enzyme immunoassays) before and 1 month after receiving a third dose of vaccine (D3). A machine learning model for predicting antibody response was created using the extreme gradient boosting (XGBoost) algorithm and validated using bootstrap validation.
Results
634 (82.3%) SOTRs were seropositive for antibodies against the spike protein before and after D3. Shorter time since transplant, mycophenolate use, corticosteroid use, and older age were key risk factors, collectively attributing to 86.6% of the model’s predictive ability. In the bootstrap validation, we observed a C-statistic of 0.80 (95% CI; 0.75, 0.83) and Brier score of 0.14 (95% CI; 0.13, 0.15), representing a good prediction performance and an 11.7% (95% CI; 7.6%,
14.4%) improvement in calibration over the non-informative model. A second model predicting antibody response after the second vaccine was created and assessed on its ability to predict antibody response after the third dose; this model showed a similarly high C-statistic (0.78 [95% CI; 0.74, 0.82]), suggesting that SOTRs with higher risk of negative antibody response to two doses remain at high risk for non-response even after subsequent doses.
Conclusion
Failure to generate an antibody response to SARS-CoV-2 vaccination in SOTRs can be predicted accurately. We created an online calculator for predicting lack of antibody response to D3 based off this model, enabling transplant professionals to perform more personalized risk assessments, therefore helping to identify which SOTRs may warrant prioritization for additional vaccine doses, antibody monitoring, and other protective measures.

A Machine Learning Model for Predicting Antibody Response After ThreeDoses of Vaccine Against SARS-CoV-2 in Solid Organ Transplant Recipients

Objective
This study examines trends in racial and gender diversity of trainees within Complex General Surgical Oncology fellowships. Further, this study compares the racial and gender proportions of trainees across different fields to assess potential barriers to increasing diversity within surgical oncology training programs.

Methods
Deidentified Accredited Council for Graduate Medical Education data were queried to identify surgical trainees between 2013-2021. Trainees were identified based on self-reported race and gender and were stratified based on residency type (i.e., general surgery and the overall trainee workforce, composed of all trainees in every program) and fellowship program if applicable. Chi-squared tests were used to assess differences between groups and trends.

Results
A significantly lower proportion of individuals who are underrepresented in medicine (URMs) trained in surgical oncology fellowships (8.9%) compared with both the overall trainee pool (12.8%) and general surgery residency programs (13.1%) (p < 0.05). There was no significant increase in URM representation in surgical oncology fellowships across the study period. In addition, there was a significantly lower proportion of females training in surgical oncology fellowships (38.6%) compared with the overall trainee pool (45.6%) (p < 0.05). Despite a significant increase in female representation in general surgery residency and other surgical fellowships, there was no significant increase in female representation in surgical oncology fellowships across the study period.

Conclusions
This study identifies disparities in gender and racial minority representation within ACGME-accredited Complex General Surgical Oncology fellowship training programs. While steps have been taken to expand diversity, more needs to be done to combat the systemic barriers that both racial minorities and women face during their training.

Analysis of Racial/Ethnic Minority and Female Representation in theSurgical Oncology Training Pathway

Introduction: Risk calculators to predict post-operative surgical site infections (SSI) often rely on logistic regression (LR) analysis. Machine learning models are able incorporate a greater number of input variables by identifying non-linear relationships. Automated machine learning (AutoML) processes regularly outperform regular machine learning (ML) and LR methods for predictive accuracy outside of healthcare settings. AutoML systems have not yet been applied to predict post-operative surgical site infections. 

Methods: We used an AutoML system developed and released by Amazon in 2020, AutoGluon v0.3.1, to predict post-operative SSI in the 2019 ACS NSQIP database. A total of 3,049,617 patients and 79 pre-operative variables were included. Post-operative SSI was defined as a superficial, deep or organ-space infection that occurred within 30 days of the surgery and was not present prior to surgery. Models were trained for four hours to optimize performance on the Brier score, with lower being better. Validation of all performance metrics was done using the 2019 ACS NSQIP database. 

Results: 2.41% of the patients (n = 73,581) developed post-operative SSI. Brier scores were calculated for each model with the top performing model being an ensembled XGBoost model having a Brier score of 0.00287 on the validation set. The corresponding AUROC and AUC-PR was 0.768 and 0.110 respectively (Figure).

Conclusions: Automated machine learning models offer similar discriminatory characteristics to existing postoperative SSI calculators. Future post-operative SSI models may benefit from AutoML analysis.

Automated machine learning (AutoML) with AutoGluon to predict post-operative surgical site infection (SSI) using the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database

In the United States, >30 million people (10.5% of the population) have diabetes, both diagnosed and undiagnosed. Many of these patients go on to develop diabetes related complications, such as peripheral neuropathy; these patients are also prone to foot injury. The purpose of this study is to determine the outcome of an isolated foot burn in the diabetic patient. A retrospective chart review of adult (>18yo) patients admitted to a major metropolitan burn center at a safety-net hospital from 2008-2020 with an isolated burn to the lower extremity and a diagnosis of diabetes mellitus. The primary outcome was Hospital length of stay, The secondary outcome was infection, number of operations, amputations, and mortality. Subgroup analysis was done to see how HbA1C affect patient’s outcome. A total of 136 patients were included for evaluation. 79% of the patient were male. 84% of the patients were <65yo and the mean age was 54.1yo and HbA1C of 8.99. Scald injury was most common (54%). The average burn size was 2.29% TBSA. 54.5% of the patients had neuropathy. The average hospital length of stay was 15 days ± 14.5 SD. Mean length of stay for all patients at our burn center is 6.55 days/% TBSA burned (internal data). 73.5% of the patients underwent surgical excision. 22% of the patients underwent an amputation and 3.7% were admitted to the intensive care unit with an average ICU length of stay of 7 Additionally, there was 1 inpatient mortality. The study revealed that scald burn was the most common mechanism of burn. Diabetic patients delay seeking medical attention and have extended hospital length of stay, High rate of infection and amputation. Most of these burn injuries and outcomes are preventable with improved education of diabetic patient on foot burn and glycemic control.

DFB: Tiny burn, big problem - The implications of a diabetic foot burn  

Abstract Title: Efficiency of IES device in facilitating distraction enterogenesis for treating short gut syndrome.

Background
Short gut syndrome (SGS) is intestinal failure because of inadequate intestinal length often encountered by pediatric surgeons. In SGS, gut adaptation and enteral absorption is low, often requiring long term parenteral nutrition for adequate development. This poses increased risk for complications including line sepsis, necrotizing enterocolitis, and liver failure. Surgical options like small bowel implantation pose significant risks and often provide limited gut expansion. We aim to experimentally evaluate the efficiency of the intestinal expansion sleeve (IES) in determining lengthening of the native bowel. We hypothesize that intestinal expansion commensurate to the IES compression can be achieved already at time of surgery.

Methods
IES devices were made using proprietary cylindrical material with helicoid trusses and isometric ends measuring 30mm in length. Ends of the device were coated with a barium-sealant mixture preventing distress and improved visualization after placement. IES devices were pre-contracted over a dilator, leading to diametric expansion. Mechanical characterization of IES devices and native small intestine segments were performed using an Instron 8874 Biaxial servo hydraulic fatigue testing system. IES devices were implanted in ex vivo intestinal segments of Sprague Dawley rats. Post-deployment gut expansion was measured using calipers. Lastly, histological analysis of the gut tissue was performed for native and experimental tissue following IES removal.

Results
IES devices deployed in rat small intestine immediately produced lengthening of 2.17 ± .17cm to 2.75 ± .22cm (p<.001, n=11). Mechanical characterization demonstrated IES exerted longitudinal forces of 0.13 ± 0.01 N to 0.22 ± 0.01 N upon expansion to post deployment length. Mechanical characterization of native small bowel demonstrated that forces greater than 1.88 ± .21 N produced rupturing of the tissue. The data proves IES devices provide significant expansion without risk of small intestinal failure. Histological examination showed significantly decreased thickness of serosal, muscular, and mucosal layers of the small intestine. 

Conclusion
This study shows that distraction enterogenesis and intestinal lengthening can be achieved using novel IES devices without the risk of mechanical failure. The findings of this study ex-vivo specimens need further corroboration in vivo for long term outcomes.

Efficiency of IES device in facilitating distraction enterogenesis for treating short gut syndrome.

Background: This study identifies factors associated with an extended hospital length of stay (LOS), exceeding the Center for Medicare and Medicaid Services (CMS) predicted LOS in pediatric transplant patients, based off of patients’ actual coded diagnostic related group (DRG) by hospital billing. DRG codes are not specific to pediatric patients. 

Methods: We conducted a retrospective chart review of 45 patients who received a solid organ transplant at a single academic pediatric hospital between January 2018- December 2021. All patients who underwent transplant surgeries were included regardless of the outcome. Clinical data was collected and analyzed.

Results: The average age was 10 years, 64% male and 44% white. Of the 45 patients, 27 were kidney recipients, 12 heart, and 6 liver. 81%(n=21) of kidney, 75%(n=9) of heart, and 67%(n=4) of liver transplant patients were noted to have exceeded their predicted LOS. The average number of exceeded days was 2.1 for kidney, 104.8 for heart, and 16.6 for liver recipients. 
Factors associated with exceeding LOS in kidney transplant patients included longer operative time (262.9-vs-220.6minutes,(p=0.01)) and greater warm ischemia time (42.1-vs-31.4minutes,(p=0.00)), cold ischemia time was not significantly different. Protective factors for discharge within the predicted timeframe included early transplantation from the time of admission (0-vs-0.27days after admission, (p=0.005)) and live organ transplantation (60%-vs-9%,(p=0.01)). However the relative significance of these factors may be influenced by possible discrepancies in hospital coding. 36.4% of kidney transplant patients who exceeded LOS were on hemodialysis with 31.8% on peritoneal dialysis however only 4.6% received the DRG code Kidney transplant with hemodialysis. DRG codes with hemodialysis have longer expected LOS than without.
Patients who underwent heart and liver transplantation showed minimal significant differences across the analyzed factors, likely due to the limited number of patients who underwent these procedures at our institution. 

Conclusion: Most solid organ transplant patients, regardless of organ transplanted, where noted to have exceeded the expected LOS for their procedure according to CMS billing. Clinical data from these patients’ hospital stay can be utilized to mitigate factors associated with exceeding LOS and should be used to adjust CMS LOS predictions to be specific for pediatric patients.

Factors Impacting Length of Hospital Stay in Pediatric Transplant Patients

Mucoepidermoid Carcinoma (MEC) in Remission with Gefitinib

Background: Acute cholecystitis is commonly treated with laparoscopic cholecystectomy, if feasible. However, critically ill patients can be managed with a percutaneous cholecystostomy tube (PCT) for biliary drainage. This is a temporizing measure and does not represent a final treatment. We aimed to compare the outcomes of performing an interval cholecystectomy vs. conservative management after PCT placement. 
Methods: We conducted a retrospective study of all patients with a PCT placed for acute calculous cholecystitis (ACC) at a single center from October 2010-March 2015. 
Results: Ninety-five patients (median age 79 years) underwent PCT placement for ACC. Only 26.3% of patients underwent interval cholecystectomy. The mortality rate within 6 weeks of ACC diagnosis was higher in the non-surgical group but this was not statistically significant. The number of re-admissions and complications of biliary disease was higher in the surgical group before undergoing interval cholecystectomy, specifically, choledocholithiasis (44% vs. 21.4%; p=0.03). Patients who had an ICU admission [ OR 0.21; 95% CI 0.07-0.66] or increased age [OR 0.94; 95% CI 0.89-0.98] were less likely to undergo interval cholecystectomy. Nine cholecystectomies were performed laparoscopic, 6 were converted to open and 10 were done in an open fashion. The complication rate in the first 30 days after cholecystectomy was 56%. Most complications occurred when surgery was performed in an open or converted to open technique (11/14=78.6%) vs. laparoscopic (3/14=21.4%).
Conclusion: The relatively high incidence of biliary complications in the period between PCT placement and cholecystectomy calls for timely cholecystectomy in patients treated with PCT. When feasible, patients with a history of ACC should undergo interval cholecystectomy. 


Prophylactic enoxaparin fails to prevent thrombosis in high-risk pediatric inflammatory bowel disease

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