Survival Benefit of First Single-Organ Deceased Donor Kidney Transplantation Compared With Long-term Dialysis Across Ages in Transplant-Eligible Patients With Kidney Failure

Abstract

ImportanceKidney transplant is considered beneficial in terms of survival compared with continued dialysis for patients with kidney failure. However, randomized clinical trials are infeasible, and available evidence from cohort studies is at high risk of bias.ObjectiveTo compare restricted mean survival times (RMSTs) between patients who underwent transplant and patients continuing dialysis across transplant candidate ages and depending on waiting time, applying target trial emulation methods.Design, Setting, and ParticipantsIn this retrospective cohort study, patients aged 18 years or older appearing on the wait list for their first single-organ deceased donor kidney transplant between January 1, 2000, and December 31, 2018, in Austria were evaluated. Available data were obtained from the Austrian Dialysis and Transplant Registry and Eurotransplant and included repeated updates on wait-listing status and relevant covariates. Data were analyzed between August 1, 2019, and December 23, 2021.ExposuresA target trial was emulated in which patients were randomized to either receive the transplant immediately (treatment group) or to continue dialysis and never receive a transplant (control group) at each time an organ became available.Main Outcomes and MeasuresThe primary outcome was time from transplant allocation to death. Effect sizes in terms of RMSTs were obtained using a sequential Cox approach.ResultsAmong the 4445 included patients (2974 men [66.9%]; mean [SD] age, 52.2 [13.2] years), transplant was associated with increased survival time across all considered ages compared with continuing dialysis and remaining on the wait list within a 10-year follow-up. The estimated RMST differences were 0.57 years (95% CI, –0.14 to 1.84 years) at age 20 years, 3.01 years (95% CI, 2.50 to 3.54 years) at age 60 years, and 2.48 years (95% CI, 1.88 to 3.04 years) at age 70 years. The survival benefit for patients who underwent transplant across ages was independent of waiting time.Conclusions and RelevanceThe findings of this study suggest that kidney transplant prolongs the survival time of persons with kidney failure across all candidate ages and waiting times.

Reporting of Observational Studies Explicitly Aiming to Emulate Randomized Trials

“…We retrieved 3133 unique records, of which 200 were included in the review (Figure 1). All reasons for excluding records after full-text review are given in eAppendix 6 in Supplement 1.…”

“…Seventy studies (35%) reported in the title that the study aimed to emulate a target trial; 180 (90%) did so in the Methods section. Twenty studies (10%) reported the study was prospectively registered, 16 of these 20 (80%)…”

“…Twenty studies (10%) reported the study was prospectively registered, 16 of these 20 (80%) also provided information on how to access the registration. One hundred and twenty-six studies (63%) specified whether a randomized clinical trial could be feasibly conducted; 61 (31%) stated that the randomized clinical trial was possible. Of the studies that stated a randomized clinical trial was possible, uncertainty in the generalizability of available trial findings was the most common reason for the target trial emulation (22 of 61 [36%]) .…”

“…Of the studies that stated a randomized clinical trial was possible, uncertainty in the generalizability of available trial findings was the most common reason for the target trial emulation (22 of 61 [36%]) . Forty-three studies (22%) reported using a guideline, most commonly (29 of 43 [67%]) the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline . There were no qualitative differences between the reporting of the target trial emulation when studies were stratified by guideline use (eAppendix 7 in Supplement 1).…”

Twenty Years, and More to Come: Learning What Makes Some Transplants Ultra-Long Survivors

“…This may seem trivial, but it corresponds to almost twice the DC-GF rate when comparing donor age differences of 20 years (1.032 to the power of 20 = 1.88) and it is especially relevant as the donor age distribution varied widely, ranging between 3 and 72 years (median 32). Although older donor age is associated with inferior outcomes, the survival advantage of transplantation over remaining on the wating list still holds true for kidneys from elderly donors ( 9 , 10 ). Likely, this benefit (although not formally tested) was particularly high in ultra-long survivor transplant recipients.…”