Purpose: Living-donor preemptive kidney transplantation (PKT) provides survival and financial benefits. However there is no guidelines to assist with PKT timing.

Method: We considered the transplant timing decisions for chronic kidney disease (CKD) patients with a compatible donor, and developed a Markov decision process in which patient's evolving health status is defined by glomerular filtration rate (GFR) level. Assuming patient is risk-neutral, the model's objective was to maximize total expected quality-adjusted survival where the transitions between the GFR levels and post-transplant life expectancies were calibrated using published literature, the SRTR's risk adjustment coefficients, and post-dialysis life expectancy tables from USRDS Annual Report. We applied the model to determine optimal transplant decisions and associated survival outcomes for a cohort of 17,556 patients from the UNOS dataset whom received kidney transplants preemptively in the between 2000 and 2017, and compared the results with their actual counterparts.

Result: The optimal GFR threshold for preemptive transplantation varied between 20 and 30 mL/min/1.73 m² for 55% of the cohort whereas the actual GFRs at the time of transplantation were in this range only for 3% of the patients. Across the whole cohort, a staggering 30% of the recipients transplanted earlier than their implied optimal GFR thresholds with an average 4.46 mL/min/1.73 m² early transplant margin between their observed GFRs at transplant and the prescribed optimal GFR thresholds. While 45% of the transplants happening before Stage 5 CKD were early, only 25% of the transplants in Stage 5 CKD were deemed to be early by our model. The survival-gain of carrying out transplantation before dialysis was 0.38 QALYs per patient which could be extended to 0.59 years for early transplantation if the timing was optimized. On average, the calculated risk of death prior to reaching target GFR level for transplantation was 6.3% per patient.

Conclusion: Optimal times to preemptive transplantation show substantial variation with respect to patient-donor characteristics. Although actual timing behaviors of preemptive kidney transplant recipients mostly appeared to be optimal, sooner preemptive transplants may noticeably fail to maximize their potential.

CITATION INFORMATION: Kurt M., Khojandi A., Barah M., Tanriover B. How Early is Too Early for a Preemptive Kidney Transplant? A Markov Decision Process-Based Retrospective Analysis Am J Transplant. 2017;17 (suppl 3).

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