Prediction of thirty-day morbidity and mortality after duodenal switch using an artificial neural network.

BACKGROUND: Understanding factors that increase risk of both mortality and specific measures of morbidity after duodenal switch (DS) is important in deciding to offer this weight loss operation. Artificial neural networks (ANN) are computational deep learning approaches that model complex interactions among input factors to optimally predict an outcome. Here, a comprehensive national database is examined for patient factors associated with poor outcomes, while comparing the performance of multivariate logistic regression and ANN models in predicting these outcomes. METHODS: 2907 DS patients from the 2019 Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database were assessed for patient factors associated with the previously validated composite endpoint of 30-day postoperative reintervention, reoperation, readmission, or mortality using bivariate analysis. Variables associated (P ≤ 0.05) with the endpoint were imputed in a multivariate logistic regression model and a three-node ANN with 20% holdback for validation. Goodness-of-fit was assessed using area under receiver operating curves (AUROC). RESULTS: There were 229 DS patients with the composite endpoint (7.9%), and 12 mortalities (0.4%). Associated patient factors on bivariate analysis included advanced age, non-white race, cardiac history, hypertension requiring 3 + medications (HTN), previous foregut/obesity surgery, obstructive sleep apnea (OSA), and higher creatinine (P ≤ 0.05). Upon multivariate analysis, independently associated factors were non-white race (odds ratio 1.40; P = 0.075), HTN (1.55; P = 0.038), previous foregut/bariatric surgery (1.43; P = 0.041), and OSA (1.46; P = 0.018). The nominal logistic regression multivariate analysis (n = 2330; R2 = 0.02, P < 0.001) and ANN (R2 = 0.06; n = 1863 [training set], n = 467 [validation]) models generated AUROCs of 0.619, 0.656 (training set) and 0.685 (validation set), respectively. CONCLUSION: Readily obtainable patient factors were identified that confer increased risk of the 30-day composite endpoint after DS. Moreover, use of an ANN to model these factors may optimize prediction of this outcome. This information provides useful guidance to bariatricians and surgical candidates alike.

Care of the Patient After Metabolic and Bariatric Surgery.

Weight loss surgery, also known as metabolic and bariatric surgery (MBS), is an effective weight loss treatment and is associated with reduced mortality and improvements in obesity-related health conditions and quality of life. Postsurgical anatomical and physiologic changes include decreased absorption of micronutrients and alterations in gut-brain hormonal regulation that affect many aspects of health. Patients require ongoing monitoring of their physical and mental health for lasting success. Internists, particularly primary care clinicians, are in an ideal position to monitor for nonserious complications in the short and long term, adjust management of chronic diseases accordingly, and monitor for mental health changes. This article reviews key issues that internists should be aware of for supporting patients' health in the short and long term after MBS.

Gastroesophageal Reflux Disease Outcomes After Vertical Sleeve Gastrectomy and Gastric Bypass.

OBJECTIVE: The objective of this study is to assess whether vertical sleeve gastrectomy (VSG) increases the incidence of gastroesophageal reflux disease (GERD), esophagitis and Barrett esophagus (BE) relative to patients undergoing Roux-en-Y gastric bypass (RYGB) in patients with and without preoperative GERD. SUMMARY OF BACKGROUND DATA: Concerns for potentiation of GERD, supported by multiple high-quality retrospective studies, have hindered greater adoption of the VSG. METHODS: From the OptumLabs Data Warehouse, VSG and RYGB patients with ≥2 years enrollment were identified and matched by follow-up time. GERD [reflux esophagitis, prescription for acid reducing medication (Rx) and/or diagnosis of BE], upper endoscopy (UE), and re-admissions were evaluated beyond 90 days. RESULTS: A total of 8362 patients undergoing VSG were matched 1:1 to patients undergoing RYGB, on the basis of post-operative follow-up interval. Age, sex, and follow-up time were similar between the 2 groups (P > 0.05). Among all patients, postoperative GERD was more frequently observed in VSG patients relative to RYGB patients (60.2% vs 55.6%, respectively; P < 0.001), whereas BE was more prevalent in RYGB patients (0.7% vs 1.1%; P = 0.007). Postoperatively, de novo esophageal reflux symptomatology was more common in VSG patients (39.3% vs 35.3%; P < 0.001), although there was no difference in development of the histologic diagnoses reflux esophagitis and BE. Furthermore, postoperative re-admission was higher in the RYGB cohort (38.9% vs 28.9%; P < 0.001). CONCLUSIONS: Compared to RYGB, VSG may not have inferior long-term GERD outcomes, while also leading to fewer re-hospitalizations. These data challenge the prevailing opinion that patients with GERD should undergo RYGB instead of VSG.

Hemodynamic Parameters in the Assessment of Fluid Status in a Porcine Hemorrhage and Resuscitation Model.

BACKGROUND: Measuring fluid status during intraoperative hemorrhage is challenging, but detection and quantification of fluid overload is far more difficult. Using a porcine model of hemorrhage and over-resuscitation, it is hypothesized that centrally obtained hemodynamic parameters will predict volume status more accurately than peripherally obtained vital signs. METHODS: Eight anesthetized female pigs were hemorrhaged at 30 ml/min to a blood loss of 400 ml. After each 100 ml of hemorrhage, vital signs (heart rate, systolic blood pressure, mean arterial pressure, diastolic blood pressure, pulse pressure, pulse pressure variation) and centrally obtained hemodynamic parameters (mean pulmonary artery pressure, pulmonary capillary wedge pressure, central venous pressure, cardiac output) were obtained. Blood volume was restored, and the pigs were over-resuscitated with 2,500 ml of crystalloid, collecting parameters after each 500-ml bolus. Hemorrhage and resuscitation phases were analyzed separately to determine differences among parameters over the range of volume. Conformity of parameters during hemorrhage or over-resuscitation was assessed. RESULTS: During the course of hemorrhage, changes from baseline euvolemia were observed in vital signs (systolic blood pressure, diastolic blood pressure, and mean arterial pressure) after 100 ml of blood loss. Central hemodynamic parameters (mean pulmonary artery pressure and pulmonary capillary wedge pressure) were changed after 200 ml of blood loss, and central venous pressure after 300 ml of blood loss. During the course of resuscitative volume overload, changes were observed from baseline euvolemia in mean pulmonary artery pressure and central venous pressure after 500-ml resuscitation, in pulmonary capillary wedge pressure after 1,000-ml resuscitation, and cardiac output after 2,500-ml resuscitation. In contrast to hemorrhage, vital sign parameters did not change during over-resuscitation. The strongest linear correlation was observed with pulmonary capillary wedge pressure in both hemorrhage (r2 = 0.99) and volume overload (r2 = 0.98). CONCLUSIONS: Pulmonary capillary wedge pressure is the most accurate parameter to track both hemorrhage and over-resuscitation, demonstrating the unmet clinical need for a less invasive pulmonary capillary wedge pressure equivalent.

Marijuana use does not affect the outcomes of bariatric surgery.

BACKGROUND: The decriminalization of marijuana and legalization of derived products requires investigation of their effect on healthcare-related outcomes. Unfortunately, little data are available on the impact of marijuana use on surgical outcomes. We aimed to determine the effect of marijuana use on 30-day complications and 1-year weight loss following laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG). METHODS: At a large academic center, 1176 consecutive patients undergoing primary bariatric surgery from 2012 to 2017 were identified and separated into cohorts according to marijuana use. The only exclusions were 19 patients lost to follow-up. Propensity score matching, using logistic regression according to preoperative age, gender, BMI, and comorbid conditions, yielded 73 patient pairs for the control and study arms. All patients were followed two years postoperatively. RESULTS: Excess BMI lost did not differ between marijuana users and controls at 3 weeks (23.0% vs 18.9%, p = 0.095), 3 months (42.0% vs 38.1%, p = 0.416), 6 months (60.6% vs 63.1%, p = 0.631), 1 year (78.2% vs 77.3%, p = 0.789), or 2 years (89.1% vs 74.5%, p = 0.604). No differences in the rate of major 30-day postoperative complications, including readmission, infection, thromboembolic events, bleeding events and reoperation rates, were found between groups. Follow-up rate at two years was lower in marijuana users (12.3% vs 27.4%, p = 0.023). CONCLUSION: This study suggests marijuana use has no impact on 30-day complications or weight loss following bariatric surgery, and should not be a contraindication to bariatric surgery.

Prediction of thirty-day morbidity and mortality after laparoscopic sleeve gastrectomy: data from an artificial neural network.

BACKGROUND: Multiple patient factors may convey increased risk of 30-day morbidity and mortality after laparoscopic vertical sleeve gastrectomy (LVSG). Assessing the likelihood of short-term morbidity is useful for both the bariatric surgeon and patient. Artificial neural networks (ANN) are computational algorithms that use pattern recognition to predict outcomes, providing a potentially more accurate and dynamic model relative to traditional multiple regression. Using a comprehensive national database, this study aims to use an ANN to optimize the prediction of the composite endpoint of 30-day readmission, reoperation, reintervention, or mortality, after LVSG. METHODS: A cohort of 101,721 LVSG patients was considered for analysis from the 2016 Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program national dataset. Select patient factors were chosen a priori as simple, pertinent and easily obtainable, and their association with the 30-day endpoint was assessed. Those factors with a significant association on both bivariate and multivariate nominal logistic regression analysis were incorporated into a back-propagation ANN with three nodes each assigned a training value of 0.333, with k-fold internal validation. Logistic regression and ANN models were compared using area under receiver-operating characteristic curves (AUROC). RESULTS: Upon bivariate analysis, factors associated with 30-day complications were older age (P = 0.03), non-white race, higher initial body mass index, severe hypertension, diabetes mellitus, non-independent functional status, and previous foregut/bariatric surgery (all P < 0.001). These factors remained significant upon nominal logistic regression analysis (n = 100,791, P < 0.001, r2= 0.008, AUROC = 0.572). Upon ANN analysis, the training set (80% of patients) was more accurate than logistic regression (n = 80,633, r2= 0.011, AUROC = 0.581), and it was confirmed by the validation set (n = 20,158, r2= 0.012, AUROC = 0.585). CONCLUSIONS: This study identifies a panel of simple and easily obtainable preoperative patient factors that may portend increased morbidity after LSG. Using an ANN model, prediction of these events can be optimized relative to standard logistic regression modeling.

Postoperative bleeding after laparoscopic Roux en Y gastric bypass: predictors and consequences.

BACKGROUND: Laparoscopic Roux-en-Y gastric bypass (LRYGB) is a common, safe and effective bariatric procedure. Bleeding is a significant source of postoperative morbidity. We aimed to determine the incidence, outcomes, and predictors of postoperative bleeding after LRYGB. METHODS: LRYGB patients included in the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) 2015 dataset were identified. Preoperative and intraoperative factors were tested for associations with bleeding using univariable and multivariable logistic regression analysis. Outcomes of length of stay, in-hospital mortality, 30-day mortality, discharge disposition, and 30-day complications among patients with and without clinically significant postoperative bleeding were compared using multivariable regression. RESULTS: In the 43,280 LRYGB patients included in this analysis, postoperative bleeding occurred in 652 (1.51%) patients. Of these, 165 (25.3%) underwent a re-operation and 97 (14.9%) underwent an unplanned endoscopy for 'bleeding'. Postoperative bleeding was associated with a longer median postoperative length of stay (4 vs. 2 days), higher in-hospital mortality (1.23 vs. 0.04%), higher 30-day mortality (1.38 vs. 0.15%), discharge to an extended-care facility (3.88 vs. 0.6%), and higher rates of major complications (all P < 0.05). Independent predictors of postoperative bleeding included; a history of renal insufficiency (OR 2.55, 95% CI 1.43-4.52), preoperative therapeutic anticoagulation (OR 2.44, 95% CI 1.69-3.53), and revisional surgery (OR 1.45, 95% CI 1.06-1.97). Intraoperative associated factors included conversions (OR 3.37, 95% CI 1.42-7.97), and drain placement (OR 1.40, 95% CI 1.18-1.67). Robotic approaches resulted in independently lower postoperative bleeding rates (OR 0.50, 95% CI 0.32-0.77). CONCLUSIONS: Postoperative bleeding occurs in 1.5% of patients undergoing a LRYGB and is associated with significantly increased morbidity and mortality. We have identified patient and operative factors that are independently associated with postoperative bleeding.

Open and Endovascular Management of Inferior Mesenteric Artery Aneurysms: A Report of Two Cases.

Inferior mesenteric artery (IMA) aneurysms are a rare entity, attributing to 1% of Splanchnic aneurysms (Edogawa S, Shibuya T, Kurose K et al. Inferior mesenteric artery aneurysm: case report and literature review. Ann Vasc Dis 2013;6:98-101), often found incidentally on evaluation for other intra-abdominal pathologies. Similar to other visceral arterial aneurysms, there is an estimated 20-50% risk of potentially fatal rupture and repair is generally recommended. We report 2 patients with IMA aneurysms, using them as cases to illustrate feasibility of both open and endovascular management options. Patient 1 is a 69-year-old male with bilateral claudication found to have an asymptomatic 20-mm IMA aneurysm. This patient underwent aortobifemoral bypass with branch polytetrafluoroethylene graft to distal IMA after excision of IMA aneurysm. Patient 2 is a 32-year-old male who underwent an ex vivo renal artery aneurysm repair and was noted on routine follow-up to have an incidental saccular 1.5-cm IMA aneurysm for which he underwent endovascular coil embolization. Both patients had an unremarkable postoperative course with a notable absence of stigmata of bowel ischemia.

Hyperlactemia Predicts Surgical Mortality in Patients Presenting With Acute Stanford Type-A Aortic Dissection.

OBJECTIVE: Inspired by the limited facility of the Penn classification, the authors aimed to determine a rapid and optimal preoperative assessment tool to predict surgical mortality after acute Stanford type-A aortic dissection (AAAD) repair. DESIGN: Patients who underwent an attempted surgical repair of AAAD were determined using a de-identified single institution database. The charts of 144 patients were reviewed retrospectively for preoperative demographics and surrogates for disease severity and malperfusion. Bivariate analysis was used to determine significant (p≤0.05) predictors of in-hospital and 1-year mortality, the primary endpoints. Receiver operating characteristic curve generation was used to define optimal cut-off values for continuous predictors. SETTING: Single center, level 1 trauma, university teaching hospital. PARTICIPANTS: The study included 144 cardiac surgical patients with acute type-A aortic dissection presenting for surgical correction. INTERVENTIONS: Surgical repair of aortic dissection with preoperative laboratory samples drawn before patient transfer to the operating room or immediately after arterial catheter placement intraoperatively. MEASUREMENTS AND MAIN RESULTS: The study cohort comprised 144 patients. In-hospital mortality was 9%, and the 1-year mortality rate was 17%. Variables that demonstrated a correlation with in-hospital mortality included an elevated serum lactic acid level (odds ratio [OR] 1.5 [1.3-1.9], p<0.001), a depressed ejection fraction (OR 0.91 [0.86-0.96], p = .001), effusion (OR 4.8 [1.02-22.5], p = 0.04), neurologic change (OR 5.3 [1.6-17.4], p = 0.006), severe aortic regurgitation (OR 8.2 [2.0-33.9], p = 0.006), and cardiopulmonary resuscitation (OR 6.8 [1.7-26.9], p = 0.01). Only an increased serum lactic acid level demonstrated a trend with 1-year mortality using univariate Cox regression (hazard ratio 1.1 [1.0-1.1], p = 0.006). Receiver operating characteristic analysis revealed optimal cut-off lactic acid levels of 6.0 mmol/L and 6.9 mmol/L for in-hospital and 1-year mortality, respectively. CONCLUSION: Lactic acidosis, ostensibly as a surrogate for systemic malperfusion, represents a novel, accurate, and easily obtainable preoperative predictor of short-term mortality after attempted AAAD repair. These data may improve identification of patients who would not benefit from surgery.

Prediction of Prolonged Ventilation after Coronary Artery Bypass Grafting: Data from an Artificial Neural Network.

OBJECTIVES: The need for mechanical ventilation 24 hours after coronary artery bypass grafting (CABG) is considered a morbidity by the Society of Thoracic Surgeons. The purpose of this investigation was twofold: to identify simple preoperative patient factors independently associated with prolonged ventilation and to optimize prediction and early identification of patients prone to prolonged ventilation using an artificial neural network (ANN). METHODS: Using the institutional Adult Cardiac Database, 738 patients who underwent CABG since 2005 were reviewed for preoperative factors independently associated with prolonged postoperative ventilation. Prediction of prolonged ventilation from the identified variables was modeled using both "traditional" multiple logistic regression and an ANN. The two models were compared using Pearson r2 and area under the curve (AUC) parameters. RESULTS: Of 738 included patients, 14% (104/738) required mechanical ventilation ≥ 24 hours postoperatively. Upon multivariate analysis, higher body-mass index (BMI; odds ratio [OR] 1.10 per unit, P < 0.001), lower ejection fraction (OR 0.97 per %, P = 0.01) and use of cardiopulmonary bypass (OR 2.59, P = 0.02) were independently predictive of prolonged ventilation. The Pearson r2 and AUC of the multivariate nominal logistic regression model were 0.086 and 0.698 ± 0.05, respectively; analogous statistics of the ANN model were 0.159 and 0.732 ± 0.05, respectively.BMI, ejection fraction and cardiopulmonary bypass represent three simple factors that may predict prolonged ventilation after CABG. Early identification of these patients can be optimized using an ANN, an emerging paradigm for clinical outcomes modeling that may consider complex relationships among these variables.

Unregulated saphenous vein graft distension decreases tissue viscoelasticity.

OBJECTIVES: Unregulated intraoperative distension of human saphenous vein (SV) graft leads to supraphysiologic luminal pressures and causes acute physiologic and cellular injury to the conduit. The effect of distension on tissue viscoelasticity, a biophysical property critical to a successful graft, is not well described. In this investigation, we quantify the loss of viscoelasticity in SV deformed by distension and compare the results to tissue distended in a pressure-controlled fashion. MATERIALS AND METHODS: Unmanipulated porcine SV was used as a control or distended without regulation and distended with an in-line pressure release valve (PRV). Rings were cut from these tissues and suspended on a muscle bath. Force versus time tracings of tissue constricted with KCl (110 mM) and relaxed with sodium nitroprusside (SNP) were fit to the Hill model of viscoelasticity, using mean absolute error (MAE) and r2-goodness of fit as measures of conformity. RESULTS: One-way ANOVA analysis demonstrated that, in tissue distended manually, the MAE was significantly greater and the r2-goodness of fit was significantly lower than both undistended tissues and tissues distended with a PRV (p<0.05) in KCl-induced vasoconstriction and SNP-induced vasodilation. CONCLUSIONS: Unregulated manual distension of SV graft causes loss of viscoelasticity and such loss may be mitigated with the use of an in-line PRV.

Traditional graft preparation decreases physiologic responses, diminishes viscoelasticity, and reduces cellular viability of the conduit: A porcine saphenous vein model.

Traditional methods of intraoperative human saphenous vein preparation for use as bypass grafts can be deleterious to the conduit. The purpose of this study was to characterize acute graft preparation injury, and to mitigate this harm via an improved preparation technique. Porcine saphenous veins were surgically harvested (unprepared controls, UnP) and prepared using traditional (TraP) and improved preparations (ImP). The TraP used unregulated radial distension, marking with a surgical skin marker and preservation in heparinized normal saline. ImP used pressure-regulated distension, brilliant blue FCF-based pen marking and preservation in heparinized Plasma-Lyte A. Rings from each preparation were suspended in a muscle bath for characterization of physiologic responses to vasoactive agents and viscoelasticity. Cellular viability was assessed using the methyl thiazolyl tetrazolium (MTT) assay and the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay for apoptosis. Contractile responses to potassium chloride (110 mM) and phenylephrine (10 µM), and endothelial-dependent and independent vasodilatory responses to carbachol (0.5 µM) and sodium nitroprusside (1 µM), respectively, were decreased in TraP tissues compared to both UnP and ImP tissues (p ⩽ 0.05). TraP tissues demonstrated diminished viscoelasticity relative to UnP and ImP tissues (p ⩽ 0.05), and reduced cellular viability relative to UnP control (p ⩽ 0.01) by the MTT assay. On the TUNEL assay, TraP tissues demonstrated a greater degree of apoptosis relative to UnP and ImP tissues (p ⩽ 0.01). In conclusion, an improved preparation technique prevents vascular graft smooth muscle and endothelial injury observed in tissues prepared using a traditional approach.

Prediction of excess weight loss after laparoscopic Roux-en-Y gastric bypass: data from an artificial neural network.

INTRODUCTION: Laparoscopic Roux-en-Y gastric bypass (LRYGB) has become the gold standard for surgical weight loss. The success of LRYGB may be measured by excess body mass index loss (%EBMIL) over 25 kg/m(2), which is partially determined by multiple patient factors. In this study, artificial neural network (ANN) modeling was used to derive a reasonable estimate of expected postoperative weight loss using only known preoperative patient variables. Additionally, ANN modeling allowed for the discriminant prediction of achievement of benchmark 50% EBMIL at 1 year postoperatively. METHODS: Six hundred and forty-seven LRYGB included patients were retrospectively reviewed for preoperative factors independently associated with EBMIL at 180 and 365 days postoperatively (EBMIL180 and EBMIL365, respectively). Previously validated factors were selectively analyzed, including age; race; gender; preoperative BMI (BMI0); hemoglobin; and diagnoses of hypertension (HTN), diabetes mellitus (DM), and depression or anxiety disorder. Variables significant upon multivariate analysis (P < .05) were modeled by "traditional" multiple linear regression and an ANN, to predict %EBMIL180 and %EBMIL365. RESULTS: The mean EBMIL180 and EBMIL365 were 56.4 ± 16.5 % and 73.5 ± 21.5%, corresponding to total body weight losses of 25.7 ± 5.9% and 33.6 ± 8.0%, respectively. Upon multivariate analysis, independent factors associated with EBMIL180 included black race (B = -6.3%, P < .001), BMI0 (B = -1.1%/unit BMI, P < .001), and DM (B = -3.2%, P < .004). For EBMIL365, independently associated factors were female gender (B = 6.4%, P < .001), black race (B = -6.7%, P < .001), BMI0 (B = -1.2%/unit BMI, P < .001), HTN (B = -3.7%, P = .03), and DM (B = -6.0%, P < .001). Pearson r(2) values for the multiple linear regression and ANN models were 0.38 (EBMIL180) and 0.35 (EBMIL365), and 0.42 (EBMIL180) and 0.38 (EBMIL365), respectively. ANN prediction of benchmark 50% EBMIL at 365 days generated an area under the curve of 0.78 ± 0.03 in the training set (n = 518) and 0.83 ± 0.04 (n = 129) in the validation set. CONCLUSIONS: Available at https://redcap.vanderbilt.edu/surveys/?s=3HCR43AKXR, this or other ANN models may be used to provide an optimized estimate of postoperative EBMIL following LRYGB.

Impaired weight loss in laparoscopic adjustable gastric banding patients over 50 years of age: diabetes mellitus as an independent risk factor.

INTRODUCTION: Laparoscopic adjustable gastric banding (LAGB) represents a safe and effective bariatric procedure, particularly for patients over 50. Preoperative risk factors for impaired post-LAGB excess weight loss are not well characterized for this population. This study aimed to identify demographics, characteristics or comorbidities associated with excess weight loss at 6 and 12 months postoperatively (EWL180 and EWL365, respectively) for these patients. METHODS: One hundred and seventeen LAGB patients >50 years of age from 2005 to 2014 were retrospectively reviewed for factors potentially associated with EWL180 and EWL365. Rationally selected variables chosen for analysis included age, race, gender, initial body mass index and preoperative weight loss; comorbidities assessed included hypertension, psychiatric disorders and diabetes mellitus (DM). Variables correlated with EWL180 or EWL365 on bivariate linear regression analysis (P ≤ .05) were input into multivariate linear regression analysis to confirm independent association. RESULTS: Preoperative DM (B = -9.1% EWL; 95% CI -13.6, -4.5%; P < .001) and African-American race (B = -8.8% EWL; 95% CI -17.3, -0.3%; P = .05) were independent risk factors for impaired EWL180. Only DM was a risk factor for impaired EWL365 (B = -9.7% EWL; 95% CI -17.7, -1.8%; P = .02). CONCLUSIONS: LAGB is a successful operation in patients >50 years of age. Preoperative DM is an independent risk factor for impaired EWL in this cohort.

Red cell distribution width is a novel biomarker that predicts excess body-mass index loss 1 year after laparoscopic Roux-en-Y gastric bypass.

INTRODUCTION: Bariatric surgery is the most effective method for producing sustained weight loss, improving obesity-associated comorbidities and reducing inflammation in the morbidly obese population. The red cell distribution width (RDW) is a novel marker of inflammation that is usually reported as part of a complete blood count. In this study, we tested our hypothesis that red cell distribution width might represent a novel biomarker predictive of excess body-mass index loss (EBMIL) following laparoscopic Roux-en-Y gastric bypass (LRYGB). METHODS: Five hundred and forty-seven LRYGB patients included from a single institution were individually reviewed, noting both preoperative RDW and percent excess BMI loss at 6 months and 1 year post-LRYGB (%EBMIL180 and %EBMIL365, respectively). Bivariate and multivariate linear regression analysis was conducted between age, gender, initial body-mass index (BMI0) and RDW and each of the two endpoints, to assess the independence of RDW as a predictor of postoperative success. RESULTS: The median RDW was 13.9 (13.3-14.6) %, and median EBMIL180 and EBMIL365 were 55.4 (45.2-66.7) % and 71.3 (58.9-87.8) %, respectively. After controlling for age, gender and BMI0, RDW was associated with %EBMIL365 (B = -1.4 [-2.8 to -0.002] %, P = .05), but not %EBMIL180 (B = -0.6 [-1.6 to 0.5] %, P = .30. Upon Kruskal-Wallis analysis, patients with a preoperative RDW > 15.0 % had significantly lower %EBMIL than those in the <13.0 % (P < .001) and 13.0-15.0 % (P < .01) strata. CONCLUSIONS: RDW is predictive of EBMIL at 1 year following LRYGB. This represents a novel preoperative biomarker that may provide clinically useful prognostic information.

Preoperative Predictors of 30-Day Mortality and Prolonged Length of Stay after Above-Knee Amputation.

BACKGROUND: The above-knee amputation (AKA) is an operation of last resort with high postoperative morbidity and mortality. This study identifies preoperative risk factors predictive of both 30-day mortality and extended length of stay (LOS) in AKA patients. METHODS: Two hundred ninety-five AKA patients from 2004 to 2013 from a single institution were retrospectively reviewed using a deidentified electronic medical record. Rationally selected factors potentially influencing 30-day mortality and LOS were chosen, including demographics, etiologies, vascular surgical history, lifestyle factors, comorbidities, and laboratory values. Variables trending with one of the end points on bivariate analysis (P ≤ 0.10) were entered into multivariate forward stepwise regression models to determine independence as a risk factor (P ≤ 0.05). Subgroup analysis of AKA patients without a traumatic, burn, or malignant etiology was similarly conducted. RESULTS: Within the 295 patient cohort, 60% of the patients were male, 18% were African American, mean age was 58 years and mean body mass index was 28 kg/m(2). The 30-day mortality rate was 9%, and mean postoperative LOS of discharged patients was 9.3 days. Upon logistic regression, thrombocytopenia (platelet count < 250 × 10(6)/mL, P < 0.001, odds ratio 6.1) and preoperative septic shock (P = 0.02, odds ratio 5.1) were identified as independent risk factors for 30-day mortality. Upon linear regression, burn etiology (P < 0.001, B = 15.8 days), leukocytosis (white blood cell count > 12 × 10(6)/mL, P < 0.001, B = 6.2 days), and guillotine amputation (P < 0.001, B = 7.6 days) were independently associated with prolonged LOS. Excluding patients with AKAs due to trauma, burn, or malignancy, only thrombocytopenia (platelet count < 250 × 10(6)/mL, P < 0.001, odds ratio 10.2) and leukocytosis (white blood cell count > 12 × 10(6)/mL, P = 0.01, B = 5.2 days) were independent risk factors for in-hospital mortality and prolonged LOS, respectively. CONCLUSIONS: Preoperative septic shock and thrombocytopenia are independent risk factors for 30-day mortality after AKA, while burn etiology, leukocytosis, and guillotine amputation contribute to prolonged LOS. Awareness of these risk factors may help enhance both preoperative decision making and expectations of the hospital admission.

The impact of gout guidelines.

PURPOSE OF REVIEW: This review discusses the impact of recent treatment guidelines for the management of gout and the barriers to treating gout patients. RECENT FINDINGS: Multiple guidelines for both the treatment and prevention of gout have been put forth in the last decade including those from the British Rheumatism Society; the European League Against Rheumatism; the Multinational Evidence, Expertise, Exchange Initiative; the Japanese Society of Gout and Nucleic Acid Metabolism; the American College of Rheumatology. These guidelines are designed to facilitate the management of gout by providers with key recommendations for the management of hyperuricemia, which is the greatest risk factor for developing gout. However, despite the extant guidelines, overall adherence to recommendations and uptake have been slow and initiation of urate-lowering therapy, titration of dosing, and monitoring of serum urate is infrequent. Greater education in proper management as well as increased awareness of new treatment strategies appear to be the primary reasons for this gap and offer avenues for improvement in management as well as areas for further research. SUMMARY: Gout remains a treatment challenge for both acute and chronic disease. Despite the availability of management guidelines, primary care providers are struggling with appropriate management of the disease. More research tools and strategies are needed to improve overall outcomes and quality of care.

Prediction of in-hospital mortality after ruptured abdominal aortic aneurysm repair using an artificial neural network.

OBJECTIVE: Ruptured abdominal aortic aneurysm (rAAA) carries a high mortality rate, even with prompt transfer to a medical center. An artificial neural network (ANN) is a computational model that improves predictive ability through pattern recognition while continually adapting to new input data. The goal of this study was to effectively use ANN modeling to provide vascular surgeons a discriminant adjunct to assess the likelihood of in-hospital mortality on a pending rAAA admission using easily obtainable patient information from the field. METHODS: Of 332 total patients from a single institution from 1998 to 2013 who had attempted rAAA repair, 125 were reviewed for preoperative factors associated with in-hospital mortality; 108 patients received an open operation, and 17 patients received endovascular repair. Five variables were found significant on multivariate analysis (P < .05), and four of these five (preoperative shock, loss of consciousness, cardiac arrest, and age) were modeled by multiple logistic regression and an ANN. These predictive models were compared against the Glasgow Aneurysm Score. All models were assessed by generation of receiver operating characteristic curves and actual vs predicted outcomes plots, with area under the curve and Pearson r(2) value as the primary measures of discriminant ability. RESULTS: Of the 125 patients, 53 (42%) did not survive to discharge. Five preoperative factors were significant (P < .05) independent predictors of in-hospital mortality in multivariate analysis: advanced age, renal disease, loss of consciousness, cardiac arrest, and shock, although renal disease was excluded from the models. The sequential accumulation of zero to four of these risk factors progressively increased overall mortality rate, from 11% to 16% to 44% to 76% to 89% (age ≥ 70 years considered a risk factor). Algorithms derived from multiple logistic regression, ANN, and Glasgow Aneurysm Score models generated area under the curve values of 0.85 ± 0.04, 0.88 ± 0.04 (training set), and 0.77 ± 0.06 and Pearson r(2) values of .36, .52 and .17, respectively. The ANN model represented the most discriminant of the three. CONCLUSIONS: An ANN-based predictive model may represent a simple, useful, and highly discriminant adjunct to the vascular surgeon in accurately identifying those patients who may carry a high mortality risk from attempted repair of rAAA, using only easily definable preoperative variables. Although still requiring external validation, our model is available for demonstration at https://redcap.vanderbilt.edu/surveys/?s=NN97NM7DTK.

Race as a predictor of delay from diagnosis to endarterectomy in clinically significant carotid stenosis.

OBJECTIVE: Prompt carotid endarterectomy (CEA) in clinically significant carotid stenosis is important in the prevention of neurologic sequelae. The greatest benefit from surgery is obtained by prompt revascularization on diagnosis. It has been demonstrated that black patients both receive CEA less frequently than white patients do and experience worse postoperative outcomes. We sought to test our hypothesis that black race is an independent risk factor for a prolonged time from sonographic diagnosis of carotid stenosis warranting surgery to the day of operation (TDO). METHODS: From 1998 to 2013 at a single institution, 166 CEA patients were retrospectively reviewed using Synthetic Derivative, a de-identified electronic medical record. Factors potentially affecting TDO, including demographics, preoperative cardiac stress testing, degree of stenosis, smoking status, and comorbidities, were noted. Multivariate analysis was performed on variables that trended with prolonged TDO on univariate analysis (P < .10) to determine independent (P < .05) predictors of TDO. Subgroup analyses were further performed on the symptomatic and asymptomatic stenosis cohorts. RESULTS: There were 32 black patients and 134 white patients studied; the mean TDO was 78 ± 17 days vs 33 ± 3 days, respectively (P < .001). In addition to the need for preoperative cardiac stress testing, black race was the only variable that demonstrated a trend with (P < .10) or was an independent risk factor for (P < .05) prolonged TDO among all patients (B = 42 days; P < .001) and within the symptomatic (B = 35 days; P = .08) and asymptomatic (B = 35 days; P = .003) cohorts. On Kaplan-Meier analysis, black patients in each stratum of symptomatology (all, symptomatic, and asymptomatic patients) experienced prolonged TDO (log-rank, P < .03 for all three groups). CONCLUSIONS: Black race is a risk factor for a temporal delay in CEA for carotid stenosis. Awareness of this disparity may help surgeons avoid undesirable delays in operation for their black patients.

Prediction of 30-Day Morbidity and Mortality After Conversion of Sleeve Gastrectomy to Roux-en-Y Gastric Bypass: Use of an Artificial Neural Network.

BACKGROUND: Conversion of sleeve gastrectomy to Roux-en-Y gastric bypass is indicated primarily for unsatisfactory weight loss or gastroesophageal reflux disease (GERD). This study aimed to use a comprehensive database to define predictors of 30-day reoperation, readmission, reintervention, or mortality. An artificial neural network (ANN) was employed to optimize prediction of the composite endpoint (occurrence of 1+ morbid event). METHODS: Areview of 8895 patients who underwent conversion for weight-related or GERD-related indications was performed using the 2021 MBSAQIP national dataset. Demographics, comorbidities, laboratory values, and other factors were assessed for bivariate and subsequent multivariable associations with the composite endpoint (P ≤ .05). Factors considered in the multivariable model were imputed into a three-node ANN with 20% randomly withheld for internal validation, to optimize predictive accuracy. Models were compared using receiver operating characteristic (ROC) curve analysis. RESULTS: 39% underwent conversion for weight considerations and 61% for GERD. Rates of 30-day reoperation, readmission, reintervention, mortality, and the composite endpoint were 3.0%, 7.1%, 2.1%, .1%, and 9.1%, respectively. Of the nine factors associated with the composite endpoint on bivariate analysis, only non-white race (P < .001; odds ratio 1.4), lower body-mass index (P < .001; odds ratio .22), and therapeutic anticoagulation (P = .001; odds ratio 2.0) remained significant upon multivariable analysis. Areas under ROC curves for the multivariable regression, ANN training, and validation sets were .587, .601, and .604, respectively. DISCUSSION: Identification of risk factors for morbidity after conversion offers critical information to improve patient selection and manage postoperative expectations. ANN models, with appropriate clinical integration, may optimize prediction of morbidity.