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Nonparametric estimation of the association between liver transplantation waiting time and posttransplant graft failure

Wang, Chunyan (2016) Nonparametric estimation of the association between liver transplantation waiting time and posttransplant graft failure. Master's Thesis, University of Pittsburgh. (Unpublished)

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Abstract

Liver transplantation is the most effective treatment for patients with end-stage liver disease. While many factors are associated with posttransplant graft failure, it has been suspected that liver transplant waiting time is negatively associated with posttransplant survival. Due to the suspicion, efforts have been made to reduce wait time for patients. There were some studies investigating this relationship recently. However, these studies were performed either with restricted samples or using data from a single center, and the results were inconclusive. For example, a study showed that after the Model for End-Stage Liver Disease (MELD) era, a longer waiting time predicts longer posttransplant survival for adult patients with hepatocellular carcinoma, whereas another study found no significant relationship between waiting time and posttransplant survival.

In this study, we quantified the time-varying association (time-varying odds ratio) between liver transplant waiting time and posttransplant mortality in the presence of retransplantation as a competing risk. We also applied two different methods to estimate the cumulative incidence of posttransplant mortality. In the first method, the univariate cumulative incidence function method, we assume independence between the liver transplant waiting time and posttransplant survival. The second method, the bivariate cumulative incidence function method, takes into account the association between transplant waiting time and posttransplant survival. Our analytic dataset was extracted from the United Network for Organ Sharing (UNOS) Standard Transplant Analysis and Research (STAR) database. The subjects in our study included 1,265 transplant candidates who were first on the liver transplant waiting list from 2002 to 2012 and were 1-11 years old. Our analysis showed that liver transplant waiting time is positively associated with posttransplant survival. Further investigation is needed to understand whether this finding was because of survivor bias; that is, those who were able to wait longer were healthier. Our analysis also indicated that retransplantation has a weak association with liver transplant waiting time.

PUBLIC HEALTH SIGNIFICANCE: We applied two different methods to pediatric liver transplant data in estimating cumulative incidence of posttransplant mortality. The findings will be the first step to help the liver transplant community understand the impact of liver transplant waiting time on posttransplant survival, and will help researchers further identify indicators of liver transplantation for reducing posttransplant mortality thus have a significant impact on future public health research.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Wang, Chunyanchunyanw@pitt.edu
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorChang, Chung-Chou H.changjh@umpc.edu
Committee MemberCheng, Yuyucheng@pitt.edu
Committee MemberYouk, Adaayouk@pitt.edu
Date: 29 June 2016
Date Type: Publication
Defense Date: 18 April 2016
Approval Date: 29 June 2016
Submission Date: 26 March 2016
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 50
Institution: University of Pittsburgh
Schools and Programs: Graduate School of Public Health > Biostatistics
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Liver transplant; Successive events; Competing risks; Cumulative incidence function; Odds ratio
Date Deposited: 29 Jun 2016 18:58
Last Modified: 30 Jun 2016 05:15
URI: http://d-scholarship.pitt.edu/id/eprint/27353

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