13 research outputs found
Clustering Survival Outcomes using Dirichlet Process Mixture
Motivated by the national evaluation of mortality rates at kidney transplant centers in the United States, we sought to assess transplant center long- term survival outcomes by applying a methodology developed in Bayesian non-parametrics literature. We described a Dirichlet process model and a Dirichlet process mixture model with a Half-Cauchy for the estimation of the risk- adjusted effects of the transplant centers. To improve the model performance and interpretability, we centered the Dirichlet process. We also proposed strategies to increase model\u27s classification ability. Finally we derived statistical measures and created graphical tools to rate transplant centers and identify outlying centers with exceptionally good or poor performance. The proposed method was evaluated through simulation, and then applied to assess kidney transplant centers from a national organ failure registry
A Dirichlet process mixture model for survival outcome data: assessing nationwide kidney transplant centers
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110837/1/sim6438.pd
Composite Scores for Transplant Center Evaluation: A New Individualized Empirical Null Method
Risk-adjusted quality measures are used to evaluate healthcare providers
while controlling for factors beyond their control. Existing healthcare
provider profiling approaches typically assume that the risk adjustment is
perfect and the between-provider variation in quality measures is entirely due
to the quality of care. However, in practice, even with very good models for
risk adjustment, some between-provider variation will be due to incomplete risk
adjustment, which should be recognized in assessing and monitoring providers.
Otherwise, conventional methods disproportionately identify larger providers as
outliers, even though their provider effects need not be "extreme.'' Motivated
by efforts to evaluate the quality of care provided by transplant centers, we
develop a composite evaluation score based on a novel individualized empirical
null method, which robustly accounts for overdispersion due to unobserved risk
factors, models the marginal variance of standardized scores as a function of
the effective center size, and only requires the use of publicly-available
center-level statistics. The evaluations of United States kidney transplant
centers based on the proposed composite score are substantially different from
those based on conventional methods. Simulations show that the proposed
empirical null approach more accurately classifies centers in terms of quality
of care, compared to existing methods
Heart and Lung Transplantation in the United States, 1997–2006
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73552/1/j.1600-6143.2008.02175.x.pd
Heart and Lung Transplantation in the United States, 1996–2005
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74833/1/j.1600-6143.2007.01783.x.pd
Liver regeneration after living donor transplantation: Adult‐to‐adult living donor liver transplantation cohort study
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109827/1/lt23966.pd
Hepatocellular Carcinoma Recurrence and Death Following Living and Deceased Donor Liver Transplantation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75606/1/j.1600-6143.2007.01802.x.pd
Liver transplant recipient survival benefit with living donation in the model for endstage liver disease allocation era
Receipt of a living donor liver transplant (LDLT) has been associated with improved survival compared with waiting for a deceased donor liver transplant (DDLT). However, the survival benefit of liver transplant has been questioned for candidates with Model for Endstage Liver Disease (MELD) scores <15, and the survival advantage of LDLT has not been demonstrated during the MELD allocation era, especially for low MELD patients. Transplant candidates enrolled in the Adult‐to‐Adult Living Donor Liver Transplantation Cohort Study after February 28, 2002 were followed for a median of 4.6 years. Starting at the time of presentation of the first potential living donor, mortality for LDLT recipients was compared to mortality for patients who remained on the waiting list or received DDLT (no LDLT group) according to categories of MELD score (<15 or ≥15) and diagnosis of hepatocellular carcinoma (HCC). Of 868 potential LDLT recipients (453 with MELD <15; 415 with MELD ≥15 at entry), 712 underwent transplantation (406 LDLT; 306 DDLT), 83 died without transplant, and 73 were alive without transplant at last follow‐up. Overall, LDLT recipients had 56% lower mortality (hazard ratio [HR] = 0.44, 95% confidence interval [CI] 0.32‐0.60; P < 0.0001). Among candidates without HCC, mortality benefit was seen both with MELD <15 (HR = 0.39; P = 0.0003) and MELD ≥15 (HR = 0.42; P = 0.0006). Among candidates with HCC, a benefit of LDLT was not seen for MELD <15 (HR = 0.82, P = 0.65) but was seen for MELD ≥15 (HR = 0.29, P = 0.043). Conclusion: Across the range of MELD scores, patients without HCC derived a significant survival benefit when undergoing LDLT rather than waiting for DDLT in the MELD liver allocation era. Low MELD candidates with HCC may not benefit from LDLT. (H EPATOLOGY 2011;54:1313–1321)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86878/1/24494_ftp.pd
Liver transplant recipient survival benefit with living donation in the MELD allocation era,,
Receipt of a living donor liver transplant (LDLT) has been associated with improved survival compared with waiting for a deceased donor liver transplant (DDLT). However, the survival benefit of liver transplant has been questioned for candidates with model for end-stage liver disease (MELD) scores< 15, and the survival advantage of LDLT has not been demonstrated during the MELD allocation era, especially for low MELD patients. Transplant candidates enrolled in the Adult-to-Adult Living Donor Liver Transplantation Cohort Study after 02/28/02 were followed for a median of 4.6 years. Starting at the time of presentation of the first potential living donor, mortality for LDLT recipients was compared to mortality for patients who remained on the waiting list or received DDLT (no LDLT group) according to categories of MELD score
Hospitalization Rates Before and After Adult-to-Adult Living Donor or Deceased Donor Liver Transplantation
To compare rates of hospitalization before and after adult-to-adult living donor liver transplant (LDLT) and deceased donor liver transplant (DDLT)