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Dive into the research topics where Andrew J. Walker is active.

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Featured researches published by Andrew J. Walker.


Clinical Gastroenterology and Hepatology | 2017

A Prospective Multicenter Study Evaluating Learning Curves and Competence in Endoscopic Ultrasound and Endoscopic Retrograde Cholangiopancreatography Among Advanced Endoscopy Trainees: The Rapid Assessment of Trainee Endoscopy Skills Study

Sachin Wani; Matthew Hall; Samuel Han; Meer Akbar Ali; Brian C. Brauer; Linda Carlin; Amitabh Chak; Dan Collins; Gregory A. Cote; David L. Diehl; Christopher J. DiMaio; Andrew M. Dries; Ihab I. El-Hajj; Swan Ellert; Kimberley Fairley; Ashley L. Faulx; Larissa L. Fujii-Lau; Srinivas Gaddam; Seng Ian Gan; Jonathan P. Gaspar; Chitiki Gautamy; Stuart R. Gordon; Cynthia L. Harris; Sarah Hyder; Ross Jones; Stephen Kim; Srinadh Komanduri; Ryan Law; Linda Lee; Rawad Mounzer

BACKGROUND & AIMS: On the basis of the Next Accreditation System, trainee assessment should occur on a continuous basis with individualized feedback. We aimed to validate endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) learning curves among advanced endoscopy trainees (AETs) by using a large national sample of training programs and to develop a centralized database that allows assessment of performance in relation to peers. METHODS: ASGE recognized training programs were invited to participate, and AETs were graded on ERCP and EUS exams by using a validated competency assessment tool that assesses technical and cognitive competence in a continuous fashion. Grading for each skill was done by using a 4‐point scoring system, and a comprehensive data collection and reporting system was built to create learning curves by using cumulative sum analysis. Individual results and benchmarking to peers were shared with AETs and trainers quarterly. RESULTS: Of the 62 programs invited, 20 programs and 22 AETs participated in this study. At the end of training, median number of EUS and ERCP performed/AET was 300 (range, 155–650) and 350 (125–500), respectively. Overall, 3786 exams were graded (EUS, 1137; ERCP‐biliary, 2280; ERCP‐pancreatic, 369). Learning curves for individual end points and overall technical/cognitive aspects in EUS and ERCP demonstrated substantial variability and were successfully shared with all programs. The majority of trainees achieved overall technical (EUS, 82%; ERCP, 60%) and cognitive (EUS, 76%; ERCP, 100%) competence at conclusion of training. CONCLUSIONS: These results demonstrate the feasibility of establishing a centralized database to report individualized learning curves and confirm the substantial variability in time to achieve competence among AETs in EUS and ERCP. ClinicalTrials.gov: NCT02509416.


Transplant International | 2010

Screening colonoscopy and detection of neoplasia in asymptomatic, average-risk, solid organ transplant recipients: case-control study.

Bret J. Spier; Andrew J. Walker; Daniel Cornett; Patrick R. Pfau; Richard B. Halberg; Adnan Said

The aim of this study was to evaluate the detection of colonic neoplasia in an average‐risk population of SOT recipients. Studies regarding colonic neoplasia in solid organ transplantation (SOT) recipients have demonstrated mixed results due to the inclusion of above average‐risk patients. We performed a case–control study of 102 average‐risk SOT recipients who underwent screening colonoscopy, compared with an average‐risk, age and sex‐matched control group (n = 287). Cancer rates were compared with an age‐matched cohort from the National Cancer Institute’s Survival, Epidemiology, and End Results (SEER) database. There was no difference in number of patients with adenomas (P = 1.00). There was no difference in polyps per patient (P = 0.31). Although the number of advanced lesions (excluding adenocarcinoma) between groups did not differ (P = 0.25), there were two adenocarcinomas identified in the SOT group and none in the control group (P = 0.068). Detection of colorectal cancer was an unexpected finding in the SOT cohort and was more likely when compared to age‐matched cancer incidence generated by the SEER database. These results suggest no increased adenoma detection in SOT recipients, but with more cases of colorectal cancer than anticipated. Given previous, larger, transplant database studies demonstrating increased colorectal cancer rates, more frequent screening may be justified.


Transplantation | 2009

Utility of colonoscopy in the evaluation of diarrhea in solid organ transplant recipients.

John P. Rice; Bret J. Spier; Daniel Cornett; Andrew J. Walker; Kelly Richie; Patrick R. Pfau

Background. Diarrhea is common in solid organ transplant recipients. Colonoscopy with random biopsies is performed frequently in the diagnostic evaluation of the posttransplant population with diarrhea. The purpose of this study was to determine the sensitivity of colonoscopy with random biopsy in determining a specific diagnosis and changing management in solid organ transplant recipients with diarrhea. Methods. From October 1996 to June 2008, 88 patients were identified who had undergone solid organ transplantation and subsequently underwent colonoscopy for an indication of “diarrhea.” These patient’s electronic medical records were reviewed to determine patient demographics, laboratory results, findings on colonoscopy and histopathology, and any subsequent diagnoses made and management changes in relation to the diarrhea. Results. Eighty-eight patients (mean age 54 years, 65% male) underwent colonoscopy a mean of 69 months after transplantation. Abnormal colonoscopic findings were seen in 16 (18.2%) patients. Histopathology was abnormal in 17/80 (21.3%). However, only eight (9.1%) had findings on colonoscopy or pathologic condition that led to specific diagnosis being made. In addition, only nine (10.2%) patients had a change in medical management as a direct result of colonoscopy with biopsy. Conclusion. Although colonoscopic or histopathologic abnormalities are common in the solid organ transplant recipient with diarrhea, the findings rarely lead to a specific diagnosis or management change. Colonoscopy with biopsy should be performed only after noninvasive testing for infectious diarrhea and a thorough review and adjustment of medications. In many patients, a trial of antidiarrheal medication is warranted before colonoscopy.


Endoscopic ultrasound | 2015

Endoscopic ultrasound-guided pancreatic pseudocyst cystogastrostomy using a novel self-expandable metal stent with antimigration system: A case series

Eric M. Nelsen; Eric A. Johnson; Andrew J. Walker; Patrick R. Pfau; Deepak V. Gopal

Background and Objectives: Development of symptomatic pseudocysts after acute pancreatitis is a common occurrence. Endoscopic ultrasound (EUS)-guided transmural drainage has become the treatment of choice for symptomatic pseudocysts. Following this procedure, stent migration can occur. A recently developed fully covered biliary metal stent with antimigration system has shown promise as an alternative endoprosthetic option for cystogastrostomy. The aim of this study is to describe the success and complications of using covered metal stents with antimigration system to drain pseudocysts at a single tertiary care center. Materials and Methods: The patients undergoing cystogastrostomy using the biliary metal stent with antimigration system over the course of a 10-month period (January-November, 2014) were retrospectively reviewed and all the pertinent information including length of the follow-up, age and sex of the patient, pseudocyst size, pseudocyst size at follow-up, and symptom improvement were recorded. Results: Five patients underwent endoscopic cystogastrostomy using a biliary metal stent with antimigration system. The average age of the patients was 57 years, with all the patients being males. The average size of the largest dimension of pseudocyst was 9 cm. The average follow-up time to repeat imaging was 30 days. All the patients had a significant improvement in their pseudocyst size, with two patients having complete resolution, one patient with a residual 2 cm cyst, and another with a residual 5 cm pseudocyst at follow-up. The average size at follow-up was 2 cm. No complications occurred during the follow-up period. No episodes of stent migration occurred. All the patients had symptom improvement at follow-up. Conclusion: Using a novel biliary covered self-expandable metal stent with antimigration system with EUS guidance to drain pseudocysts appears to be a safe and effective procedure in certain settings. Our experience shows rapid cyst resolution with no complications and no stent migration. This stent gives the providers another option when performing cystogastrostomy.


Diagnostic and Therapeutic Endoscopy | 2015

Comparison of Capsule Endoscopy Findings to Subsequent Double Balloon Enteroscopy: A Dual Center Experience

Amandeep S. Kalra; Andrew J. Walker; Mark E. Benson; Anurag Soni; Nalini M. Guda; Mehak Misha; Deepak V. Gopal

Background. There has been a growing use of both capsule endoscopy (CE) and double balloon enteroscopy (DBE) to diagnose and treat patients with obscure gastrointestinal blood loss and suspected small bowel pathology. Aim. To compare and correlate sequential CE and DBE findings in a large series of patients at two tertiary level hospitals in Wisconsin. Methods. An IRB approved retrospective study of patients who underwent sequential CE and DBE, at two separate tertiary care academic centers from May 2007 to December 2011, was performed. Results. 116 patients were included in the study. The mean age ± SD was 66.6 ± 13.2 years. There were 56% males and 43.9% females. Measure of agreement between prior capsule and DBE findings was performed using kappa statistics, which gave kappa value of 0.396 with P < 0.001. Also contingency coefficient was calculated and was found to be 0.732 (P < 0.001). Conclusions. Our study showed good overall agreement between DBE and CE. Findings of angioectasia had maximum agreement of 69%.


Endoscopic ultrasound | 2018

A tertiary care hospital's 10 years' experience with rectal ultrasound in early rectal cancer

DeepakV Gopal; Ahmed Akhter; Andrew J. Walker; Charles P. Heise; Gregory D. Kennedy; MarkE Benson; PatrickR Pfau; EricA Johnson; TerrenceJ Frick

Background and Objectives: Rectal endoscopic ultrasound (RUS) has become an essential tool in the management of rectal adenocarcinoma because of the ability to accurately stage lesions. The aim of this study was to identify the staging agreement of early RUS-staged rectal adenocarcinoma with surgical resected pathology and ultimately determine how this impacts the management of early rectal cancer (T1–T2). Methods: Retrospective chart review was performed from November 2002 to November 2013 to identify procedure indication, RUS staging data, surgical management, and postoperative surgical pathology data. Results: There were a total of 693 RUS examinations available for review and 282 of these were performed for a new diagnosis of rectal adenocarcinoma. There was staging agreement between RUS and surgical pathology in 19 out of 20 (95%) RUS-staged T1 cases. There was staging agreement between RUS and surgical pathology in 3 out of 9 (33%) RUS-staged T2 cases. There was significantly better staging agreement for RUS-staged T1 lesions compared to RUS staged T2 lesions (P = 0.002). Nearly 60% of T1N0 cancers were referred for transanal excisions (TAEs), and 78% of T2N0 cancers underwent low anterior resection. Conclusions: This study identified only a small number of T1–T2 adenocarcinomas. There was good staging agreement between RUS and surgical pathology among RUS-staged T1 lesions whereas poor staging agreement among RUS-staged T2 lesions. Although TAE is largely indicated by the staging of a T1 lesion, this approach may be less appropriate for T2 lesions due to high reported local recurrence.


Surgical Endoscopy and Other Interventional Techniques | 2010

Surgical resident's training in colonoscopy: numbers, competency, and perceptions.

Bret J. Spier; Emily T. Durkin; Andrew J. Walker; Eugene Foley; Eric A. Gaumnitz; Patrick R. Pfau


Gastroenterología y Hepatología | 2015

From Capsule Endoscopy to Balloon-Assisted Deep Enteroscopy: Exploring Small-Bowel Endoscopic Imaging.

D. Matthew Cooley; Andrew J. Walker; Deepak V. Gopal


Author | 2017

A Prospective Multicenter Study Evaluating Learning Curves and Competence in Endoscopic Ultrasound and Endoscopic Retrograde Cholangiopancreatography Among Advanced Endoscopy Trainees: The Rapid Assessment of Trainee Endoscopy Skills (RATES) Study

Sachin Wani; Matthew Hall; Samuel Han; Meer Akbar Ali; Brian C. Brauer; Linda Carlin; Amitabh Chak; Dan Collins; Gregory A. Cote; David L. Diehl; Christopher J. DiMaio; Andrew M. Dries; Ihab I. El-Hajj; Swan Ellert; Kimberley Fairley; Ashley L. Faulx; Larissa L. Fujii-Lau; Srinivas Gaddam; Seng-Ian Gan; Jonathan P. Gaspar; Chitiki Gautamy; Stuart R. Gordon; Cynthia L. Harris; Sarah Hyder; Ross Jones; Stephen Kim; Srinadh Komanduri; Ryan Law; Linda Lee; Rawad Mounzer


Gastrointestinal Endoscopy | 2015

Tu1673 Cytology With Rapid on-Site Examination (ROSE) Does Not Improve Diagnostic Yield of EUS-FNA of Pancreatic Cystic Lesions

Paul Estrada; Andrew J. Walker; Mark E. Benson; Deepak V. Gopal; Patrick R. Pfau

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Patrick R. Pfau

University of Wisconsin-Madison

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Bret J. Spier

University of Wisconsin-Madison

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Daniel Cornett

University of Wisconsin-Madison

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Deepak V. Gopal

University of Wisconsin-Madison

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Mark E. Benson

University of Wisconsin-Madison

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Amitabh Chak

Case Western Reserve University

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Ashley L. Faulx

Case Western Reserve University

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Brian C. Brauer

University of Colorado Denver

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Chitiki Gautamy

University of South Florida

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