Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Yiyi Zhang is active.

Publication


Featured researches published by Yiyi Zhang.


Journal of Surgical Education | 2012

Assessing Trainee Impact on Operative Time for Common General Surgical Procedures in ACS-NSQIP

Dominic Papandria; Daniel Rhee; Gezzer Ortega; Yiyi Zhang; Amany I. Gorgy; Martin A. Makary; Fizan Abdullah

OBJECTIVEnTo examine the effect of surgical trainee involvement on operative time for common surgical procedures. Laparoscopic appendectomy, laparoscopic cholecystectomy, and open inguinal hernia repair comprise 17.7% of the total cases sampled in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. These cases are commonly performed by residents at varying levels of surgical training.nnnSTUDY DESIGNnA cross-sectional study was performed using American College of Surgeons National Surgical Quality Improvement Program data from 2005 through 2008 selecting patients undergoing laparoscopic appendectomy, laparoscopic cholecystectomy, and open inguinal hernia repair. The primary outcome was operative time and predictive variables were resident involvement and training level. Linear regression analysis was used to compare operative times between cases performed by an attending alone and those assisted by junior (postgraduate year 1-2) or senior (postgraduate year 3-5) trainees, adjusting for patient and operative factors.nnnRESULTSnA total of 115,535 surgical cases were included, with 65,364 (59%) performed with junior or senior surgical residents. Resident participation was associated with higher operative times with no significant differences between the junior and senior cohorts; this effect persisted after controlling for potential confounding factors. Operative time increased by 16.6 minutes (95% confidence interval, 16.2-17.0) for junior residents and also by 16.6 minutes (95% confidence interval, 16.2-16.9) for senior residents.nnnCONCLUSIONSnSurgical trainees participation in common surgical procedures is associated with an increase in total operative time, with no difference between trainee seniority levels. This finding may be significant in assessing the impact of residency training programs on hospital efficiency.


Journal of Surgical Research | 2013

Risk of perforation increases with delay in recognition and surgery for acute appendicitis

Dominic Papandria; Seth D. Goldstein; Daniel Rhee; Jose H. Salazar; Jamir Arlikar; Amany I. Gorgy; Gezzer Ortega; Yiyi Zhang; Fizan Abdullah

BACKGROUNDnAppendicitis remains a common indication for urgent surgical intervention in the United States, and early appendectomy has long been advocated to mitigate the risk of appendiceal perforation. To better quantify the risk of perforation associated with delayed operative timing, this study examines the impact of length of inpatient stay preceding surgery on rates of perforated appendicitis in both adults and children.nnnMETHODSnThis study was a cross-sectional analysis using the National Inpatient Sample and Kids Inpatient Database from 1988-2008. We selected patients with a discharge diagnosis of acute appendicitis (perforated or nonperforated) and receiving appendectomy within 7 d after admission. Patients electively admitted or receiving drainage procedures before appendectomy were excluded. We analyzed perforation rates as a function of both age and length of inpatient hospitalization before appendectomy.nnnRESULTSnOf 683,590 patients with a discharge diagnosis of appendicitis, 30.3% were recorded as perforated. Over 80% of patients underwent appendectomy on the day of admission, approximately 18% of operations were performed on hospital days 2-4, and later operations accounted for <1% of cases. During appendectomy on the day of admission, the perforation rate was 28.8%; this increased to 33.3% for surgeries on hospital day 2 and 78.8% by hospital day 8 (P<0.001). Adjusted for patient, procedure, and hospital characteristics, odds of perforation increased from 1.20 for adults and 1.08 for children on hospital day 2 to 4.76 for adults and 15.42 for children by hospital day 8 (P<0.001).nnnCONCLUSIONSnGreater inpatient delay before appendectomy is associated with increased perforation rates for children and adults within this population-based study. These findings align with previous studies and with the conventional progressive pathophysiologic appendicitis model. Randomized prospective studies are needed to determine which patients benefit from nonoperative versus surgically aggressive management strategies for acute appendicitis.


Journal of Public Health | 2010

Analysis of 23 million US hospitalizations: uninsured children have higher all-cause in-hospital mortality

Fizan Abdullah; Yiyi Zhang; Thomas Lardaro; Marissa Black; Paul M. Colombani; Kristin Chrouser; Peter J. Pronovost; David C. Chang

BACKGROUNDnThe number of uninsured children in the USA is increasing while the impact on childrens health of being uninsured remains largely uncharacterized. We analyzed data from more than 23 million US children to evaluate the effect of insurance status on the outcome of US pediatric hospitalization.nnnMETHODSnIn our analysis of two well-known large inpatient databases, we classified patients less than 18 years old as uninsured (self-pay) or insured (including Medicaid or private insurance). We adjusted for gender, race, age, geographic region, hospital type, admission source using regression models. In-hospital death was the primary outcome and secondary outcomes were hospital length of stay and total hospital charges adjusted to 2007 dollars.nnnRESULTSnThe crude in-hospital mortality was 0.75% for uninsured versus 0.47% for insured children, with adjusted mortality rates of 0.74 and 0.46%, respectively. On multivariate analysis, uninsured compared with insured patients had an increased mortality risk (odds ratio: 1.60, 95% CI: 1.45-1.76). The excess mortality in uninsured children in the US was 37.8%, or 16,787, of the 38,649 deaths over the 18 period of the study.nnnCONCLUSIONnChildren who were hospitalized without insurance have significantly increased all-cause in-hospital mortality as compared with children who present with insurance.


Clinical Pediatrics | 2010

Necrotizing Enterocolitis in 20 822 Infants: Analysis of Medical and Surgical Treatments

Fizan Abdullah; Yiyi Zhang; Melissa Camp; Debraj Mukherjee; Alodia Gabre-Kidan; Paul M. Colombani; David C. Chang

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of the neonate. Previous information about this disease has largely been gathered from limited series. We analyzed 13 years of the National Inpatient Sample (NIS) and 3 years of the Kids’ Inpatient Database (KID; 1997, 2000, 2003) to generate the most comprehensive profile of outcomes to date of medically versus surgically treated NEC. We identified 20 822 infants with NEC, of whom 15 419 (74.1%) and 5403 (25.9%) were undergoing medical and surgical management, respectively. Overall, surgical patients had greater length of stay, total hospital charges, and mortality. Among infants dying during admission, there was no significant difference in length of stay or charges between the medical and surgical groups. These findings highlight the need for developing a clinically relevant risk stratification tool to identify NEC patients at high risk for death.


Journal of The American College of Surgeons | 2009

Variations in Referral Patterns to High-Volume Centers for Pancreatic Cancer

David C. Chang; Yiyi Zhang; Debraj Mukherjee; Christopher L. Wolfgang; Richard D. Schulick; John L. Cameron; Nita Ahuja

BACKGROUNDnMultiple reports have demonstrated pancreatic cancer patients undergoing surgery have superior outcomes at high-volume hospitals. This study noted trends in access to high-volume centers for pancreatic resection and identified gaps in improving access.nnnSTUDY DESIGNnWe performed a retrospective analysis of the Nationwide Inpatient Sample (NIS 2000 to 2005) linked to the Area Resource File (ARF). Inclusion criteria were patients with primary diagnosis of pancreatic cancer who received pancreatic resection. The primary outcomes variable was treatment at high-volume hospitals (average annual case volume greater than 20). Independent variables included age, gender, race, Charlson Comorbidity Index score, insurance status, calendar year, and region, obtained from the Nationwide Inpatient Sample; community poverty level and density of all physicians, gastroenterologists, surgeons, and radiation oncologists were data obtained from the Area Resource File.nnnRESULTSnA total of 8,370 patients were identified. A minority (38.51%) were referred to high-volume hospitals. A significant increase in overall referral and odds of referral to a high-volume center was observed over time (22.2% in 2000 to 44.4% in 2005). Patients referred to high-volume centers were younger (61.9 versus 63.2 years, p < 0.001) and more likely to be Caucasian (81.7% versus 73.6%, p < 0.001). Patients greater than 85 years old, African Americans, Hispanics, and Asians were less likely to be referred, relative to their younger, Caucasian counterparts (p < 0.01). The overall trend toward improved referral over time was driven by improved referral among Caucasians. In multivariate analysis, access to high-volume centers was associated with calendar year, patient age, and race. In addition, increase in density of gastroenterologists or radiation oncologists in the population was also associated with higher likelihood of referral.nnnCONCLUSIONSnThis study demonstrated that less than half of pancreatic cancer patients are being referred to high-volume centers. Unlike referral in Caucasians, improvement in referral for minorities has not occurred.


Pediatric Surgery International | 2009

Congenital diaphragmatic hernia: Outcome review of 2,173 surgical repairs in US infants

Fizan Abdullah; Yiyi Zhang; Christopher M. Sciortino; Melissa Camp; Alodia Gabre-Kidan; Mitchell R. Price; David C. Chang

Congenital diaphragmatic hernia (CDH) remains one of the most challenging conditions to treat within the pediatric surgical and medical communities. In spite of modern treatment modalities, including extracorporeal membrane oxygenation (ECMO) and improved ventilatory support, mortality remains high. The present study analyzes a US database containing information from nearly 93xa0million discharges in the US. Infants with congenital diaphragmatic hernia who underwent surgical repair were identified by ICD-9 procedure code and inclusion criteria including an age at admission of less than 1xa0year. Variables of gender, race, age, geographic region, co-existing diagnoses and procedures, hospital type, hospital charges adjusted to 2006 dollars, length of stay, and inpatient mortality were collected. A total of 89% of patients were either treated initially or rapidly transferred to urban teaching hospitals for definitive treatment of CDH. The inpatient mortality rate was 10.4% with a median length of stay of 20xa0days (interquartile range of 9–40xa0days). The median inflation-adjusted total hospital charge was


Cardiology in The Young | 2010

Analysis of 8681 neonates with transposition of the great arteries: Outcomes with and without Rashkind balloon atrial septostomy

Debraj Mukherjee; Mark E. Lindsay; Yiyi Zhang; Thomas Lardaro; Hayley Osen; David C. Chang; Joel I. Brenner; Fizan Abdullah

116,210. Respiratory distress was the most common co-existing condition (68.8%) followed by esophageal reflux (27.8%). The most common concomitant procedures performed were ECMO (17.8%) and fundoplication (17.6%). This study, which represents the largest characterization of US infants who have undergone CDH repair using data from a nationally representative non-voluntary database, demonstrates that surgical repair is associated with significant mortality and morbidity.


Pediatric Blood & Cancer | 2009

Splenectomy in hereditary spherocytosis: Review of 1,657 patients and application of the pediatric quality indicators

Fizan Abdullah; Yiyi Zhang; Melissa Camp; Mark I. Rossberg; Melinda A. Bathurst; Paul M. Colombani; James F. Casella; Rosemary Nabaweesi; David C. Chang

BACKGROUNDnRashkind balloon atrial septostomy is a common cardiac procedure aimed at improving systemic oxygenation in newborns with cyanotic congenital cardiac defects, such as transposition of the great arteries. Recent reports on the safety of this procedure were from limited series at single institutions. We analysed two complementary national databases to evaluate clinically relevant outcomes of this procedure.nnnMETHODS AND RESULTSnWe performed an analysis of transposition of the great artery patients nationwide using 15 years of the Nationwide In-patient Sample and three complementary years of the Kids Inpatient Database. Variables included gender, race, age, and co-existing diagnoses. Outcomes included mortality, length of stay, and hospital charges. Comparison between patients undergoing Rashkind procedure or not was performed using Pearsons chi-square and Kruskal-Wallis tests. We identified 8681 patients with transposition of the great arteries, of whom 1742 (20%) underwent Rashkind procedure. Patients undergoing Rashkind procedure had lower mortality (10% versus 12%, p = 0.021), despite higher median co-morbidities and longer median length of stay. Rashkind procedure was not associated with increased risk of necrotising enterocolitis (1% versus 1%, p = 0.630), but was associated with nearly twice the risk of clinically recognised stroke (1% versus 0%, p = 0.046).nnnCONCLUSIONSnThis study represents the largest national analysis of transposition of the great artery patients to date, with a subset treated with Rashkind procedure. Patients not undergoing Rashkind procedure had higher mortality. Rashkind procedure was not associated with increased risk of necrotising enterocolitis, but was associated with twice the risk of stroke.


Journal of Pediatric Surgery | 2011

Necrotizing enterocolitis requiring surgery: outcomes by intestinal location of disease in 4371 infants

Yiyi Zhang; Gezzer Ortega; Melissa Camp; Hayley Osen; David C. Chang; Fizan Abdullah

The objective of the present study is to profile the outcome and safety of pediatric patients undergoing splenectomy with hereditary spherocytosis (HS) using a nationwide sample and the Agency for Healthcare Research and Quality (AHRQ) Pediatric Quality Indicators (PDIs).


Pediatrics | 2013

A Novel Multispecialty Surgical Risk Score for Children

Daniel Rhee; Jose H. Salazar; Yiyi Zhang; Jingyan Yang; Dominic Papandria; Gezzer Ortega; Adam B. Goldin; Shawn J. Rangel; Kristin Chrouser; David C. Chang; Fizan Abdullah

OBJECTIVEnThe objective of this study was to determine whether the outcomes of infants with surgically managed necrotizing enterocolitis (NEC) differ according to whether the location of NEC is in the small bowel, large bowel, or both.nnnSTUDY DESIGNnA retrospective analysis was performed using the Healthcare Cost and Utilization Project Nationwide Inpatient Sample and Kids Inpatient Database. A total of 5374 infants identified as having undergone surgical management of NEC were stratified by location of bowel affected as small bowel (SB) only, large bowel (LB) only, or both small and large bowel (SB&LB). The type of surgical operation performed was used as a proxy for the location of bowel affected.nnnRESULTSnOf the 5374 infants with a diagnosis of NEC, 4371 had an operation that allowed for stratification by location. The LB group (n = 963) fared the best in all outcomes. The SB group (n = 2126) had the longest length of stay and highest total hospital charges, and mortality was comparable with that of the SB&LB group (n = 1282).nnnCONCLUSIONSnMortality, length of stay, and total hospital charges varied according to location of bowel affected by NEC.

Collaboration


Dive into the Yiyi Zhang's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar

David C. Chang

Johns Hopkins University School of Medicine

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Daniel Rhee

Johns Hopkins University School of Medicine

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Melissa Camp

Johns Hopkins University

View shared research outputs
Researchain Logo
Decentralizing Knowledge