OPTN/SRTR 2017 Annual Data Report: Preface

Mean lifetime survival estimates following solid organ transplantation in the US and UK

AIMS

Accurately estimating mean survival after solid organ transplant (SOT) is crucial for efficient healthcare resource allocation decisions. However, registry-based post-transplant recipient survival estimates vary greatly and are incomplete. Often, the methods used in lifetime survival extrapolation may not fit complex transplant data and therefore alternative methods are required. We aimed to explore the flexible cubic spline methodology as a meaningful alternative for estimating lifetime survival following SOT.

METHODS

Survival analyses were conducted in kidney, liver, heart, and lung transplant recipients. Mean survival was estimated using flexible cubic splines on the hazard scale fitted with three knots, based on where hazards changed direction, clinical advice, and best-fit curve using Akaike and Bayesian information criterion. The tail was extrapolated when data were no longer available. Extrapolation tails were compared with general population mortality, using age-matched life table hazards, and the highest hazards were taken at all times.

RESULTS

We found that mean survival post-transplant was longest for kidney transplants (US: 22.79 years; UK: 26.58 years), followed by liver (US: 20.90 years; UK: 20.38 years), heart (US: 14.82 years; UK: 15.85 years), and lung (US: 9.28 years; UK: 9.21 years). A sensitivity analysis using two knots found differences in survival ranging from -1.30 to +4.83 years across SOTs examined.

LIMITATIONS

This study does not represent individual patient survival, survival by age groups, multiple-organ transplants, or assess factors that may impact overall or organ survival.

CONCLUSIONS

Our study estimates reflect real-world survival following SOTs and demonstrate the importance of including long-term hazards in survival estimations. These lifetime survival estimates can be used by decision-makers in situations where means are preferred over medians (e.g. population projections, budgetary estimates, and cost-effectiveness models) and can thus offer a meaningful alternative to the estimates used and accepted in current practice.

Machine learning support for decision making in kidney transplantation: step-by-step development of a technological solution (Preprint)

Background

Kidney transplantation is the preferred treatment option for patients with end-stage renal disease. To maximize patient and graft survival, the allocation of donor organs to potential recipients requires careful consideration.

Objective

This study aimed to develop an innovative technological solution to enable better prediction of kidney transplant survival for each potential donor-recipient pair.

Methods

We used deidentified data on past organ donors, recipients, and transplant outcomes in the United States from the Scientific Registry of Transplant Recipients. To predict transplant outcomes for potential donor-recipient pairs, we used several survival analysis models, including regression analysis (Cox proportional hazards), random survival forests, and several artificial neural networks (DeepSurv, DeepHit, and recurrent neural network [RNN]). We evaluated the performance of each model in terms of its ability to predict the probability of graft survival after kidney transplantation from deceased donors. Three metrics were used: the C-index, integrated Brier score, and integrated calibration index, along with calibration plots.

Results

On the basis of the C-index metrics, the neural network–based models (DeepSurv, DeepHit, and RNN) had better discriminative ability than the Cox model and random survival forest model (0.650, 0.661, and 0.659 vs 0.646 and 0.644, respectively). The proposed RNN model offered a compromise between the good discriminative ability and calibration and was implemented in a technological solution of technology readiness level 4.

Conclusions

Our technological solution based on the RNN model can effectively predict kidney transplant survival and provide support for medical professionals and candidate recipients in determining the most optimal donor-recipient pair.

Renal transplantation using vascular conduit reconstruction in deceased kidneys with multiple renal arteries and short renal veins

BACKGROUND

Transplantation of kidneys with vascular anatomical variants remains a challenge. Due to its varying success in regard to graft function after transplantation, these organs have been frequently discarded assuming in advance an unaffordable rate of vascular complications.

PATIENTS AND METHODS

We performed three kidney transplants using organs from deceased donors harboring vascular variants (multiple arteries and short veins), including an unsplittable horseshoe kidney. Different grafts harvested from the same donor aorta, common iliac artery, and inferior vena cava, were used to reconstruct the initial vascular configuration by creating single arterial and venous conduits aimed to simplify the vascular anastomoses in the recipient.

RESULTS

No post-operative complications were recorded. Warm ischemia times remained comparable to single artery renal allografts. No delayed graft function was noted in any case, and every patient regained normal renal function after transplantation.

CONCLUSIONS

Vascular reconstruction using arterial and venous grafts harvested from the same deceased donor may result a helpful tool to simplify vascular anastomoses during transplantation surgery, thus avoiding their discard in advance, minimizing perioperative complications, and enabling normal graft function rates in the long-term follow-up. The successful outcome obtained by using this approach would help to expand the donor criteria for the inclusion of organs containing vascular anatomical variants.

Patients' perceptions of a culturally targeted Hispanic Kidney Transplant Program: A mixed methods study

Disproportionately fewer waitlisted Hispanics receive living donor kidney transplants (LDKTs) compared to non-Hispanic whites. Northwestern Medicine's^® culturally targeted Hispanic Kidney Transplant Program (HKTP) is associated with a significant increase in LDKTs among Hispanics. This multisite study assessed potential kidney recipients' and donors' and/or family members' perceptions of the HKTP's cultural components through semi-structured interviews and validated surveys. Qualitative thematic analysis and descriptive statistics were performed. Thirty-six individuals participated (62% participation rate) comprising 21 potential recipients and 15 potential donors/family (mean age: 51 years, 50% female, 72% preferred Spanish). Participants felt confident about the educational information because a transplant physician delivered the education and viewed the group format as effective. Participants felt that education sessions addressed myths about transplantation shared by Hispanics. Primary use of Spanish enhanced participants' understanding of transplantation. While few knew about living donation before attending the HKTP, most were "more in favor of" kidney transplantation (97%) and living donation (97%) afterward. Few reported learning about the HKTP from outreach staff and suggested leveraging community leaders to promote HKTP awareness. Our findings suggest the HKTP's cultural components were viewed favorably and positively influenced perceptions of kidney transplantation and living donation, which may help reduce transplant disparities in Hispanics. (Clinicaltrial.gov registration # NCT03276390, date of registration: 9-7-17, retrospectively registered).