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Kidney Week

Abstract: PO2479

Effect of UNOS Kidney Allocation System on Transplantation Rates for Veterans Waitlisted at Veterans Affairs Transplant Centers

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Aggarwal, Nidhi, Michael E DeBakey VA Medical Center, Houston, Texas, United States
  • Navaneethan, Sankar D., Michael E DeBakey VA Medical Center, Houston, Texas, United States
  • Niu, Jingbo, Baylor College of Medicine, Houston, Texas, United States
  • Pan, Jenny S., Michael E DeBakey VA Medical Center, Houston, Texas, United States
  • Vangala, Chandan, Michael E DeBakey VA Medical Center, Houston, Texas, United States
  • Cotton, Ronald T., Michael E DeBakey VA Medical Center, Houston, Texas, United States
  • Ramanathan, Venkat, Michael E DeBakey VA Medical Center, Houston, Texas, United States
Background

Impact of new Kidney Allocation System (KAS) on kidney transplantation (KT) rates for Veterans waitlisted at Veterans Affairs Transplant Centers (VATC) is unknown. This study compares effect of KAS on waitlisted patients at VATC and non-VATC.

Methods

UNOS data on adult patients waitlisted for KT during January 2009 to December 2016 were obtained. Logistic regression was used to assess association between center type (VATC vs. Non-VATC), time period (pre-KAS 2009-2014 vs. post-KAS 2015-2016) and outcomes (receiving KT or death on waitlist) within 2 years of waitlisting. Odds ratio (OR) was calculated adjusting for demographic factors, comorbidities, calculated Panel Reactive Antibodies (cPRA) and Estimated Post-Transplant Survival (EPTS) score.

Results

During study period, a total of 263,410 patients were listed at non-VATC (75% pre-KAS; 25% post-KAS) and 3,150 at VATC (68% pre-KAS; 32% post-KAS). VATC patients were significantly older (58.3 vs.51.7 years), diabetics (55.4% vs. 42.5%), had lower cPRA, higher EPTS (53 vs.39%) and longer duration of dialysis (762 vs. 727 days).
Within 2 years of waitlisting, Veterans listed at VATC did not benefit from the new KAS like patients in non-VATC centers. Overall, independent of the era, Veterans tend to be transplanted lesser in this early waitlisting period. But death on waitlist was 29% lower in VATC patients. (Results are shown in the table).

Conclusion

Benefit of new KAS did not extend to Veterans listed at VATC who are older, less immunogenic and have higher EPTS score. Early benefit of KAS seen in non-VATCs could be due to "bolus effect” from transplantation of younger, highly sensitized patients. However, risk of death is significantly lower in VATC waitlisted patients.

Outcomes of patients within 2 years of waitlisting for kidney transplantation
 Kidney transplant rate
(OR, 95% CI)
Death on waitlist
(OR, 95% CI)
Post-KAS vs Pre-KAS (Non-VATC)1.30 (1.27, 1.33)* 
Post-KAS vs Pre KAS (VATC)0.94 (0.76, 1.14) 
VATC vs Non-VATC (Pre-KAS)0.70 (0.63, 0.79)* 
VATC vs Non-VATC (Post-KAS)0.49 (0.41, 0.58)* 
Post-KAS vs. Pre-KAS (Overall) 0.78 (0.75, 0.82)*
VATC vs. Non-VATC (Overall) 0.71 (0.60, 0.84)*

*p<0.01