#4680 PATIENT OUTCOMES AND DYNAMICS OF THE AUSTRALIAN KIDNEY TRANSPLANT WAITLIST: SUSPENSIONS, RETURNING TO WAITLIST, TRANSPLANTATION AND DEATHS
Authors: Mata Nicole De La , Khou Victor , Hedley James , Rosales Brenda , Morton Rachael , Webster Angela 
Published: June 2023

Abstract

Background and Aims
People on the kidney waitlist are less informed about potential temporary or permanent suspensions. Disparities may exist among those who are suspended and who return to the waitlist. In Australia, average wait times vary be state/territory and blood group, but overall is X years. We aimed to describe and evaluate factors associated with waitlist transitions and subsequent outcomes after entering the waitlist for deceased donor kidney transplant.

Method
We included all incident patients waitlisted for their first transplant from deceased donors in Australia during 2006-2019. We described all clinical transitions after entering the kidney waitlist including: active on waitlist; suspended; kidney transplant; graft failure; and death. We predicted the restricted mean survival time from waitlist entry until first transplant with 5 year time horizon and summarized the annual percentages in each clinical state until 5 years. We used flexible parametric multi-state survival models to evaluate factors associated with transitions after entering the waitlist until first transplant, reporting the hazard ratio (HR) for each transition. We used Cox proportional hazards models to evaluate factors associated with death while waiting and first transplant, reporting HR for these outcomes.

Results
Of 8,466 people who entered the kidney waitlist, 6,741 people received their first transplant (6,163 deceased donor; 506 living donor; 99 paired kidney exchange donors), 381 people died while waiting (31 active on waitlist; 350 suspended) and 1,344 were still waiting for a transplant (844 active on waitlist; 500 suspended). Nearly two-thirds (63%) were not suspended while waiting, but 2,111(25%) were suspended once and 1,016(12%) were suspended ≥2 times. Of those suspended, 47% spent a total of &lt;6 months off-waitlist. Predicted mean time from waitlist entry to transplant increased with number of suspensions, from 1.9 years (95% CI:1.8-1.9 years) in patients not suspended to 3.0 years (95% CI:2.8-3.2 years) in patients suspended once or more. For the entire cohort, the 1-year probability of transplant was 41%(95%CI:40-42%), active on waitlist was 42%(95%CI:41-43%), suspended was 11%(95%CI:10-12%) and death was 1.4% (95%CI:1.2-1.7%) (Fig. 1). At 5-years, this increased to 63% (95%CI:62-64%) transplanted, 5% (95%CI:4-5%) active on waitlist, 10% (95%CI:9-11%) suspended and 13% (95%CI:12-14%) died. Several patient factors were associated being suspended and returning to the waitlist, as well as with receiving transplant and death while waiting (Fig. 2). Having been suspended from the waitlist, increased the likeliness of further suspensions by 4.2 times (95%CI: 3.8-4.6; p &lt; 0.001) and returning to the waitlist by 50% (95%CI: 36-65%; p &lt; 0.001) but decreased the likeliness of receiving a transplant by 29% (95%CI: 62-82%; p &lt; 0.001). Being previously suspended once reduced the risk of death while waiting by 31% (HR: 0.69, 95%CI: 0.52-0.91; p &lt; 0.01), likely a paradox of being well enough to return to waitlist at least once. Socio-demographic factors were modifiers of returning to the waitlist after suspension. Males of Australian or New Zealand ethnicity (non-Indigenous) were 13% (95%CI: 4-23%) more likely to return to the waitlist compared to females of the same ethnicity (p &lt; 0.01). However, males of Aboriginal, Torres Strait Islander, Māori or Pacific Islander ethnicity had the same likeliness of returning to the waitlist as their female counterparts (p = 0.08).

Conclusion
The dynamics of the transplant waiting list were not straightforward. About one-third of patients were suspended at least once and wait 1 year longer for a transplant compared with those not suspended. Our findings will provide evidence to support more informed discussions about the patient journey from waitlist to transplantation, and aid in shared decision making.