Estimated Impact of the Number of Simultaneous Offers on Kidney Delay and Discard

Abstract

Following local decline of a recovered kidney, making regional and national offers in larger simultaneous batches might decrease discards. We simulated varying batch sizes for offers stratified by KDPI, and described likelihood of discard and delay.

METHODS: Using 2010 KPSAM-SRTR data, we simulated allocation of 3090 organs, comparing current practice to one of making (one-hour) expiring simultaneous offers to batches of transplant centers. Kidneys not matched after 10 rounds of offers were classified as discarded for excessive delay. We excluded locally allocated and 0-MM kidneys. We assumed each hour's delay increases discard probability by 5%.

RESULTS: Discard and delay decreased with increasing batch size (Table 1). Among regionally accepted offers with KDPI>85%, batch size of 2/5/10 centers resulted in 23%/81%/100% placed within 3 hours of delay. Among nationally accepted offers, batch size of 5/10/20 centers resulted in 23%/28%/56% placed within 3 hours of delay (Figure 1). For KDPI>85%, making national offers in batches of 10 centers rather than 5 decreased discard to 34% from 71%. The probability of accepting but not receiving an organ (because a higher-priority candidate received the kidney) with regional offer batch size of 10 was 38% for KDPI<0.25 and 7% for KDPI>0.85.

CONCLUSION: Making expiring simultaneous kidneys offers at regional and national levels might decrease delays and discard without over-burdening providers. For high KDPI kidneys, increasing the batch size might decrease delay of placement.