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Dive into the research topics where Gabriela M. Vargas is active.

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Featured researches published by Gabriela M. Vargas.


Annals of Surgery | 2016

Relative contributions of complications and failure to rescue on mortality in older patients undergoing pancreatectomy

Nina P. Tamirisa; Abhishek D. Parmar; Gabriela M. Vargas; Hemalkumar B. Mehta; E. Molly Kilbane; Bruce L. Hall; Henry A. Pitt; Taylor S. Riall

Background:For pancreatectomy patients, mortality increases with increasing age. Our study evaluated the relative contribution of overall postoperative complications and failure to rescue rates on the observed increased mortality in older patients undergoing pancreatic resection at specialized centers. Methods:We identified 2694 patients who underwent pancreatic resection from the American College of Surgeons’ National Surgical Quality Improvement Pancreatectomy Demonstration Project at 37 high-volume centers. Overall morbidity and in-hospital mortality were determined in patients younger than 80 years (N = 2496) and 80 years or older (N = 198). Failure to rescue was the number of deaths in patients with complications divided by the total number of patients with postoperative complications. Results:No significant differences were observed between patients younger than 80 years and those 80 years or older in the rates of overall complications (41.4% vs 39.4%, P = 0.58). In-hospital mortality increased in patients 80 years or older compared to patients younger than 80 years (3.0% vs 1.1%, P = 0.02). Failures to rescue rates were higher in patients 80 years or older (7.7% vs 2.7%, P = 0.01). Across 37 high-volume centers, unadjusted complication rates ranged from 25.0% to 72.2% and failure to rescue rates ranged from 0.0% to 25.0%. Among patients with postoperative complications, comorbidities associated with failure to rescue were ascites, chronic obstructive pulmonary disease, and diabetes. Complications associated with failure to rescue included acute renal failure, septic shock, and postoperative pulmonary complications. Conclusions:In experienced hands, the rates of complications after pancreatectomy in patients 80 years or older compared to patients younger than 80 years were similar. However, when complications occurred, older patients were more likely to die. Interventions to identify and aggressively treat complications are necessary to decrease mortality in vulnerable older patients.


Surgery | 2014

Trajectory of care and use of multimodality therapy in older patients with pancreatic adenocarcinoma

Abhishek D. Parmar; Gabriela M. Vargas; Nina P. Tamirisa; Kristin M. Sheffield; Taylor S. Riall

INTRODUCTION Multimodality therapy with chemotherapy and operative resection is recommended for patients with locoregional pancreatic cancer but is not received by many patients. OBJECTIVE To evaluate patterns in the use and timing of chemotherapy and resection and factors associated with receipt of multimodality therapy in older patients with locoregional pancreatic cancer. METHODS We used Surveillance, Epidemiology, and End Results-linked Medicare data (1992-2007) to identify patients with locoregional pancreatic adenocarcinoma. Multimodality therapy was defined as receipt of both chemotherapy and pancreatic resection. Logistic regression was used to determine factors independently associated with receipt of multimodality therapy. Log-rank tests were used to identify differences in survival for patients stratified by type and timing of treatment. RESULTS We identified 10,505 patients with pancreatic adenocarcinoma. 5,358 patients (51.0%) received either chemotherapy or surgery, with 1,166 patients (11.1%) receiving both modalities. Resection alone was performed in 1,138 patients (10.8%), and chemotherapy alone was given to 3,054 (29.1%) patients. In patients undergoing resection as the initial treatment modality, 49.4% never received chemotherapy; 97.4% of patients who underwent chemotherapy as the initial treatment modality never underwent resection. The use of multimodality therapy increased from 7.4% of patients in 1992-1995 to 13.8% of patients in 2004-2007 (P < .0001). The 2-year survival was 41.0% for patients receiving multimodality therapy, 25.1% with resection alone, and 12.5% with chemotherapy alone (P < .0001). Of the patients receiving multimodality therapy, chemotherapy was delivered in the adjuvant setting in 93.1% and in the neoadjuvant setting in 6.9%, with similar 2-year survival with either approach (neoadjuvant vs adjuvant, 46.9% vs 40.6%; P = .16). Year of diagnosis, white race, less comorbidity, and no vascular invasion were independently associated with receipt of multimodality therapy. CONCLUSION Only half of older patients with locoregional pancreatic cancer receive any treatment, and fewer than one quarter of treated patients receive multimodality therapy. Nearly all patients receiving chemotherapy as the initial treatment modality did not undergo resection, whereas half of those undergoing resection first received chemotherapy. When multimodality therapy is used, the vast majority of patients had chemotherapy in the adjuvant setting with a similar survival, regardless of approach.


Annals of Surgery | 2015

Preop-gallstones: A prognostic nomogram for the management of symptomatic cholelithiasis in older patients

Abhishek D. Parmar; Kristin M. Sheffield; Deepak Adhikari; Robert A. Davee; Gabriela M. Vargas; Nina P. Tamirisa; Yong Fang Kuo; James S. Goodwin; Taylor S. Riall

OBJECTIVE AND BACKGROUND The decision regarding elective cholecystectomy in older patients with symptomatic cholelithiasis is complicated. We developed and validated a prognostic nomogram to guide shared decision making for these patients. METHODS We used Medicare claims (1996-2005) to identify the first episode of symptomatic cholelithiasis in patients older than 65 years who did not undergo hospitalization or elective cholecystectomy within 2.5 months of the episode. We described current patterns of care and modeled their risk of emergent gallstone-related hospitalization or cholecystectomy at 2 years. Model discrimination and calibration were assessed using a random split sample of patients. RESULTS We identified 92,436 patients who presented to the emergency department (8.3%) or physicians office (91.7%) and who were not immediately admitted. The diagnosis for the initial episode was biliary colic/dyskinesia (65.3%), acute cholecystitis (26.6%), choledocholithiasis (5.7%), or gallstone pancreatitis (2.4%). The 2-year emergent gallstone-related hospitalization rate was 11.1%, with associated in-hospital morbidity and mortality rates of 56.5% and 6.5%. Factors associated with gallstone-related acute hospitalization included male sex, increased age, fewer comorbid conditions, complicated biliary disease on initial presentation, and initial presentation to the emergency department. Our model was well calibrated and identified 51% of patients with a risk less than 10% for 2-year complications and 5.4% with a risk more than 40% (C statistic, 0.69; 95% confidence interval, 0.63-0.75). CONCLUSIONS Surgeons can use this prognostic nomogram to accurately provide patients with their 2-year risk of developing gallstone-related complications, allowing patients and physicians to make informed decisions in the context of their symptom severity and its impact on their quality of life.


Cancer | 2013

Evaluating Comparative Effectiveness With Observational Data Endoscopic Ultrasound and Survival in Pancreatic Cancer

Abhishek D. Parmar; Kristin M. Sheffield; Yimei Han; Gabriela M. Vargas; Praveen Guturu; Yong Fang Kuo; James S. Goodwin; Taylor S. Riall

A previous observational study reported that endoscopic ultrasound (EUS) is associated with improved survival in older patients with pancreatic cancer. The objective of this study was to reevaluate this association using different statistical methods to control for confounding and selection bias.


Surgery | 2013

Physician follow-up and observation of guidelines in the post treatment surveillance of colorectal cancer

Gabriela M. Vargas; Kristin M. Sheffield; Abhishek D. Parmar; Yimei Han; Kimberly M. Brown; Taylor S. Riall

BACKGROUND Guidelines for post resection surveillance of colorectal cancer recommend a collection of the patients history and physical examination, testing for carcinoembryonic antigen (CEA), and colonoscopy. No consistent guidelines exist for the use of abdominal computed tomography (CT) and position emission tomography (PET)/PET-CT. The goal of our study was to describe current trends, the impact of oncologic follow-up on guideline adherence, and the patterns of use of nonrecommended tests. METHODS We used Texas Cancer Registry-Medicare-linked data (2000-2009) to identify physician visits, CEA testing, colonoscopy, abdominal CT, and PET/PET-CT scans in patients ≥ 66 years old with stage I-III colorectal cancer who underwent curative resection. Compliance with guidelines was assessed with a composite measure of physician visits, CEA tests, and colonoscopy use from start of surveillance. RESULTS In patients who survived 3 years, the overall compliance with guidelines was 25.1%. In patients seen regularly by a medical oncologist, compliance with guidelines increased to 61.5% compared with 8.8% for those not seen by a medical oncologist regularly (P < .0001). The use of abdominal CT and PET/PET-CT increased from 57.5% and 9.5%, respectively, in 2001 to 65.8% and 24.6% (P < .0001) in 2006. Patients who saw a medical oncologist were more likely to get cross-sectional imaging than those who did not (P < .0001). CONCLUSION Compliance with current minimum guidelines for post treatment surveillance of colorectal cancer is low and the use of nonrecommended testing has increased over time. Both compliance and use of nonrecommended tests are markedly increased in patients seen by a medical oncologist. The comparative effectiveness of CT and PET/PET-CT in the surveillance of colorectal cancer patients needs further examination.


Surgery | 2013

Quality of post-treatment surveillance of early stage breast cancer in Texas

Abhishek D. Parmar; Kristin M. Sheffield; Gabriela M. Vargas; Yimei Han; Celia Chao; Taylor S. Riall

BACKGROUND Only annual mammography and physical examination are recommended for the post-treatment surveillance of early stage breast cancer. METHODS We used Texas Cancer Registry-Medicare linked data (2001-2007) to identify physician visits and use of mammography, magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET) CT in patients ≥ 66 years old with ductal carcinoma in situ and stage I-III ductal carcinoma who underwent curative-intent operations. We also evaluated the trends in use of recommended and nonrecommended tests. RESULTS We identified 8,598 patients with resected ductal carcinoma in situ (37.3%) or invasive ductal cancer (62.7%). Breast-conserving therapy was performed in 59%. Only 55% saw a physician twice a year for 2 years and underwent annual mammography for 2 consecutive years in the surveillance period. Mammography use decreased from 81% in 2001 to 75% in 2007 (P < .0001), and breast MRI use rose from 0.5% to 7.0% (P < .0001). For asymptomatic patients, the use of CT/MRI of the abdomen, chest, and head was 27%, 23%, and 22%, and this slightly increased during the study period. There was a significant increase in PET/PET CT use, from 2% in 2001 to 9% in 2007 (P < .0001). There was a concomitant decrease in bone scan use from 21% in 2001 to 13% in 2007 (P < .0001). CONCLUSION Adherence to evidence-based guidelines has been substandard and the use of nonrecommended tests has persisted over the study period. The rise in PET use and attendant decrease in bone scan implicates a population receiving PET scan in lieu of bone scan for surveillance of asymptomatic metastatic disease. In an elderly population of breast cancer patients in Texas, these findings imply both underuse and overuse.


Colorectal Disease | 2017

Comparative effectiveness of chemotherapy vs resection of the primary tumour as the initial treatment in older patients with Stage IV colorectal cancer

Hemalkumar B. Mehta; Gabriela M. Vargas; Deepak Adhikari; Francesca M. Dimou; Taylor S. Riall

The objectives were to determine trends in the use of chemotherapy as the initial treatment and to evaluate the comparative effectiveness of initial chemotherapy vs resection of the primary tumour on survival (intention‐to‐treat analysis) in Stage IV colorectal cancer (CRC).


Annals of Surgery | 2015

Surgeon and Facility Variation in the Use of Minimally Invasive Breast Biopsy in Texas

Nina P. Tamirisa; Kristin M. Sheffield; Abhishek D. Parmar; Christopher J. Zimmermann; Deepak Adhikari; Gabriela M. Vargas; Yong Fang Kuo; James S. Goodwin; Taylor S. Riall

OBJECTIVE AND BACKGROUND Minimally invasive breast biopsy (MIBB) rates remain well below guideline recommendations of more than 90% and vary across geographic areas. Our aim was to determine the variation in use attributable to the surgeon and facility and determine the patient, surgeon, and facility characteristics associated with the use of MIBB. METHODS We used 100% Texas Medicare claims data (2000-2008) to identify women older than 66 years with a breast biopsy (open or minimally invasive) and subsequent breast cancer diagnosis/operation within 1 year. The percentage of patients undergoing MIBB as the first diagnostic modality was estimated for each surgeon and facility. Three-level hierarchical generalized linear models (patients clustered within surgeons within facilities) were used to evaluate variation in MIBB use. RESULTS A total of 22,711 patients underwent a breast cancer operation by 1226 surgeons at 525 facilities. MIBB was the initial diagnostic modality in 62.4% of cases. Only 7.0% of facilities and 12.9% of surgeons used MIBB for more than 90% of patients. In 3-level models adjusted for patient characteristics, the percentage of patients who received MIBB ranged from 7.5% to 96.0% across facilities (mean = 50.1%, median = 49.2%) and from 8.0% to 87.0% across surgeons (mean = 50.3%, median = 50.9%). The variance in MIBB use was attributable to facility (8.8%) and surgeon (15.4%) characteristics. Lower surgeon and facility volume, longer surgeon years in practice, and smaller facility bed size were associated with lower rates of MIBB use. CONCLUSIONS Identification of surgeon and facility characteristics associated with low use of MIBB provides potential targets for interventions to improve MIBB rates and decrease variation in use. TYPE OF STUDY Retrospective cohort.


Journal of Gastrointestinal Surgery | 2014

Trends in Treatment and Survival in Older Patients Presenting with Stage IV Colorectal Cancer

Gabriela M. Vargas; Kristin M. Sheffield; Abhishek D. Parmar; Yimei Han; Aakash Gajjar; Kimberly M. Brown; Taylor S. Riall


Journal of Gastrointestinal Surgery | 2014

Cost-Effectiveness of Elective Laparoscopic Cholecystectomy Versus Observation in Older Patients Presenting with Mild Biliary Disease

Abhishek D. Parmar; Mark D. Coutin; Gabriela M. Vargas; Nina P. Tamirisa; Kristin M. Sheffield; Taylor S. Riall

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Abhishek D. Parmar

University of Texas Medical Branch

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Kristin M. Sheffield

University of Texas Medical Branch

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Nina P. Tamirisa

University of Texas Medical Branch

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Yimei Han

University of Texas Medical Branch

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Kimberly M. Brown

University of Texas Medical Branch

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Deepak Adhikari

University of Texas Medical Branch

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Hemalkumar B. Mehta

University of Texas Medical Branch

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James S. Goodwin

University of Texas Medical Branch

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Yong Fang Kuo

University of Texas Medical Branch

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