Medical Student Research Fellowship for Summer 2012

Mentor: Eric Rosero, M.D.              
Department: Department of Anesthesiology                    
Room number:  CS2.106    
Mail Code:     9068  
Phone number:  214-648-3657                  
E-mail: eric.rosero@utsouthwestern.edu              
Project title: Nationwide in-hospital postoperative outcomes of patients with myasthenia gravis undergoing abdominal surgery               

Human subjects IRB approved project number (where applicable):       NA

Animal subjects IRB approved project number (where applicable):       NA

Project Type: patient-based (national database)

Brief Description of Project:
Myasthenia gravis is a neuromuscular autoimmune disorder characterized by antibodies against acetylcholine receptors at the neuromuscular junction. Patients have fluctuating weakness and fatigability, which increases their risk of adverse postoperative outcomes. Patients with myasthenia gravis are given special consideration when undergoing abdominal surgery. They are at higher risk for postoperative respiratory problems related to altered respiratory mechanics caused by pain, inflammation, general anesthetic agents, mechanical ventilation, and physical stress.   However, national in-hospital outcomes of patients with myasthenia gravis undergoing abdominal surgery have not been studied.

The purpose of this study is to assess nationwide incidence of in-hospital mortality, myocardial infarction, stroke, acute renal failure, pulmonary embolism, pneumonia, post-operative mechanical ventilation, and tracheostomies in myasthenic patients compared to non-myasthenic patients undergoing abdominal surgery in the United States. In addition, length of stay and charges accrued will be evaluated between the groups.

Data from the National Inpatient Sample (NIS) from 2005 to 2009 will be used to identify patients with and without a diagnosis of myasthenia gravis undergoing abdominal surgery. Baseline demographic characteristics (age, gender, and race) and hospital characteristics (teaching status, urban vs. rural location, bed size, and geographic location) will be described for each group. The Charlson comorbidity index will be calculated as a measure of comorbidity burden for each patient. Logistic regression models will be conducted based on these previously described characteristics to calculate propensity scores for each patient. These scores will be used to find a matched cohort of patients with and without myasthenia gravis who share similar characteristics. Postoperative outcomes between the two groups will be compared using appropriate statistical methods.

Role of student: The medical student will help with project design, literature review, statistical analysis, and writing the manuscript. The student will help create the database subset and help analyze the data using statistical analytics software (such as SAS).

Previous Research Activities or Publications with Medical Students:

• Rosero EB, Adesanya AO, Timaran CH, Joshi GP. Nationwide Use and Outcomes of Ambulatory Surgery in Morbidly Obese Patients in the United States. Submitted to Anesthesia and Analgesia.
• Modrall JG, Rosero EB, Valentine RJ, Timaran CH. Assessing Outcomes to Determine Whether Symptoms Related to Hypertension Justify Renal Artery Stenting. J Vasc Surg. In Press.
• Timaran CH, Rosero EB, Higuera A, Ilarraza A, Modrall JG, Clagett GP. Randomized clinical trial of open-cell vs. closed-cell stents for carotid stenting and effects of stent design on cerebral embolization. J Vasc Surg. 2011 Jun 29.
• Modrall JG, Timaran CH, Rosero EB, Chung J, Arko FA 3rd, Valentine RJ, Clagett GP, Trimmer, C. Predictors of Outcome for Renal Artery Stenting Performed for Salvage of Renal Function. J Vasc Surg. 2011 Jul 30.
• Modrall JG, Rosero EB, Leonard D, Timaran CH, Anthony T, Arko FR 3rd,Valentine RJ, Clagett GP, Trimmer C. Clinical and Kidney Morphologic Predictors of Outcome  for Renal Artery Stenting: Data to Inform Patient Selection. J Vasc Surg. . 2011 May;53(5):1282-89; discussion 1289-90. Epub 2011 Feb 12.
• Rosero EB, Peshock RM, Khera A, Clagett GP, Timaran CH. Age, sex, and ethnic distributions of mean aortic wall thickness in a multi-ethnic population-based sample. J Vasc Surg.  2011 Apr;53(4):950-7.
• Timaran CH, Rosero EB, Martinez AE, Ilarraza A, Modrall JG. Clagett GP. Atherosclerotic plaque composition and cerebral embolization after carotid stenting. J Vasc Surg. 2010 Nov;52(5):1188-95.
• Timaran CH, Rosero EB, Modrall JG, Valentine RJ, Clagett, GP. Carotid stenting-induced bradycardia and hypotension treated without atropine. Submitted to Archives of Surgery.
• Modrall JG, Rosero EB, Smith ST, Arko FR 3rd, Valentine RJ, Clagett GP, Timaran CH. Effect of Hospital Volume on In-Hospital Mortality for Renal Artery Bypass. Vasc Endovascular Surg. 2009 Jun 24.
• Rosero EB, Kane K, Clagett GP, Timaran CH. A systematic review of the limitations and approaches to improve detection and management of peripheral arterial disease in Hispanics. J Vasc Surg. 2010 Apr;51(4 Suppl):27S-35S