Kidney transplantation is the preferred treatment for patients with end-stage kidney disease, offering superior survival and quality of life compared with long-term dialysis. However, demand for donor kidneys continues to far exceed supply, resulting in prolonged waiting times for transplantation in many healthcare systems.

To improve utilisation of available organs and reduce the likelihood of potentially viable kidneys being discarded, transplant programmes have increasingly adopted expedited or out-of-sequence allocation. In this approach, kidneys may be offered outside the traditional waiting-list sequence when concerns arise that the organ may otherwise go unused. While this strategy may accelerate organ placement, it has also prompted questions regarding transparency, equity of access, and whether allocation outside the standard match-run process influences transplant outcomes.

This retrospective cohort study analysed data from the Scientific Registry of Transplant Recipients (SRTR) in the United States, covering deceased donor kidney transplants performed between 2020 and 2024. The analysis included 15 602 kidneys recovered from 8 544 deceased donors, with approximately 62% of donors being male and a mean donor age of 44 years.

Kidneys were categorised according to allocation pathway:

• Both kidneys transplanted out of sequence
• One kidney transplanted in sequence and the other out of sequence (unilateral OOS — the primary comparison group)
• A single kidney transplanted out of sequence

The paired-kidney design was key to the study’s strength: by comparing kidneys from the same donor, the investigators controlled for donor-related factors that might otherwise confound outcome comparisons between allocation pathways.
 

In a national registry analysis of 15 602 kidneys from 8 544 deceased donors, expedited kidney allocation increased dramatically over the study period, yet patient and graft survival remained comparable between kidneys transplanted within and outside the standard allocation sequence.

Of the 8 544 donors included, just over half (50.5%) had one kidney transplanted out of sequence. Unilateral out-of-sequence allocation — where one kidney from a donor was transplanted in sequence and the other was not — accounted for 38.2% of all OOS transplants during the study period. The growth was striking, as shown in the interactive chart below. (Scroll over items to view information.)

The point in the match run at which kidneys were diverted from the standard sequence also changed markedly. In 2020, kidneys ultimately placed out of sequence were first refused at a median position of approximately 393 candidates on the waiting list. By 2024, this had fallen to around the 28th position — indicating that organs were increasingly being allocated outside the standard sequence much earlier in the process.

Over the same period, donor-related reasons for refusal declined by approximately 10–15%, suggesting that decisions to allocate kidneys through expedited pathways may increasingly be driven by logistical considerations rather than donor quality alone.

Recipients of out-of-sequence kidneys differed in several respects from those receiving kidneys through the standard match run. They tended to be slightly older (median age 60 vs 57 years), were more frequently male, and more likely to be White or Asian. They were also more likely to have private health insurance (29.1% vs 23.0%) and to undergo pre-emptive transplantation prior to dialysis (17.1% vs 10.2%), suggesting that socioeconomic and healthcare access factors may influence which patients ultimately receive these organs.

Despite these differences in allocation patterns and recipient characteristics, clinical outcomes remained comparable. In adjusted analyses, unilateral out-of-sequence transplantation was not associated with a statistically significant difference in patient survival (HR 0.84; 95% CI 0.70–1.02) or graft survival (HR 0.87; 95% CI 0.70–1.08) compared with kidneys transplanted within the standard allocation sequence.

Taken together, these findings suggest that expedited kidney allocation can be used without compromising transplant outcomes. In this paired-kidney analysis, both patient and graft survival were similar regardless of whether kidneys were transplanted through the standard match run or through expedited pathways. This supports the clinical safety of transplanting organs allocated outside the traditional sequence, particularly when doing so may help prevent organ discard.

However, the study also raises important questions regarding how and when expedited allocation is used. Because kidneys from the same donor were compared, differences in donor quality are unlikely to explain why one kidney was transplanted within the standard sequence while the other was not. The rapid expansion of unilateral out-of-sequence allocation — and the dramatic shift toward earlier diversion in the match run — therefore suggests that logistical or institutional factors may increasingly influence allocation decisions.

The findings also highlight potential concerns regarding equity in access to transplantation. Recipients of out-of-sequence kidneys were more likely to have indicators associated with greater healthcare access, including private insurance and pre-emptive transplantation. While expedited allocation may improve overall organ utilisation, these observations underscore the importance of transparent governance and clearly defined allocation criteria to ensure that transplant systems remain equitable.
 

These considerations are particularly relevant in the South African context, where transplantation takes place within a resource-constrained healthcare environment characterised by limited organ availability and restricted access to long-term dialysis. Waiting times for deceased donor kidneys may extend for many years, and access to chronic dialysis in the public sector is often constrained by capacity limitations.

In this setting, each successful kidney transplant has broader implications for the healthcare system. Beyond improving survival and quality of life for the recipient, transplantation may also free a dialysis slot for another patient who might otherwise be unable to access life-sustaining treatment.

Innovations in donor matching and allocation therefore have considerable potential to expand transplant opportunities in South Africa. One promising approach is kidney paired donation, in which incompatible donor–recipient pairs are matched with other pairs to enable compatible exchanges. Through this strategy, patients who would otherwise be unable to receive a transplant because of immunological incompatibility may undergo transplantation without requiring complex desensitisation protocols.

Early paired-donation initiatives in South Africa have demonstrated that such exchanges are feasible and can facilitate transplantation for patients who previously had limited treatment options. As transplant programmes continue to evolve, expanding collaborative matching systems and strengthening allocation frameworks may represent important steps toward improving access to transplantation.

Ultimately, the findings of this study reinforce a broader principle in transplant medicine: improving access to transplantation will depend not only on increasing donor numbers but also on optimising allocation systems and matching strategies. For healthcare systems with constrained resources, such as South Africa’s, transparent allocation policies and innovative approaches such as kidney exchange programmes may play an important role in ensuring that the limited supply of donor organs benefits as many patients as possible.

Yu ME, Husain SA, Tucker EG, et al. Expedited Transplant Allocation Using a Paired Kidney Cohort. JAMA Netw Open. 2026;9(3):e260257. doi:10.1001/jamanetworkopen.2026.0257

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