Kidney Donor Outcomes Cohort (KDOC) Study

Kidney transplantation extends and improves the lives of adults with end-stage renal disease (ESRD). Live donor kidney transplantation (LDKT) has many advantages over deceased donor transplantation for the recipient, including shorter or no dialysis exposure, immediate graft function, lower perioperative morbidity and mortality, and better long-term graft and patient survival. Also, it yields significant cost savings to the healthcare system overall. These relative advantages and other advances in the field (e.g., laparoscopic techniques, paired kidney exchanges) have led transplant candidates and programs to more proactively embrace LDKT as the primary treatment option. Living kidney donors now account for 40% of all kidney transplants performed in the United States during the past 10 years, and more than 90,000 adults have undergone living donor nephrectomy in the United States over the last 20 years.

Worldwide there have been few large-scale studies examining the short- and long-term outcomes of living kidney donation, and many have been limited by retrospective, cross-sectional, and/or single-center designs with no appropriate control group. Despite efforts to enhance understanding of donor outcomes, it is clear that we have more knowledge in some areas (e.g., surgical and short-term medical complications) than in others (e.g., long-term medical complications, psychological outcomes, financial impact). The relative paucity of multisite, prospective outcome studies is concerning, especially considering the expanding donor eligibility criteria used by transplant programs today. Over the past decade, criteria for acceptance of a living donor candidate has changed: some donor candidates who would not have been considered 15 years ago (e.g., those with hypertension, obesity, or no prior relationship with the recipient) are now readily evaluated by many programs.

Recently, the transplant community and changes in federal regulations have brought attention to the need for more systematic study of living donor outcomes. While reporting outcomes over a 2-yr period is now mandated by the Organ Procurement and Transplantation Network (OPTN) and the United Network for Organ Sharing (UNOS), most transplant programs do not systematically collect donor outcome data. The lack of such data is an important problem because, without it, we will continue to have considerable variability in informed consent processes for living donors and their recipients, as well as limited data to inform clinical practice and policy development. This study directly addresses several of the recommendations made by the U.S. Department of Health and Human Services' Advisory Committee on Organ Transplantation.

A. Design Overview

This is a six center, prospective observational cohort study. A total of 280 living kidney donors, 280 LDKT recipients, and 160 healthy comparison subjects meeting all eligibility criteria will be enrolled. Participants will complete the assessment protocol at 5 time points: prior to surgery (Baseline, T1), 1 month after surgery (T2), 6 months after surgery (T3), 12 months after surgery (T4), and 24 months after surgery (T5). The rationale for selecting these time points is that they correspond to the assessment intervals currently required by the OPTN/UNOS for living donor follow-up, which were selected by the Living Donation Committee as the most appropriate time points for gathering short- and long-term follow-up data.

B. Study Participants

A total of 280 living kidney donors, 280 LDKT recipients, and 160 healthy comparison subjects meeting all eligibility criteria will be enrolled.

We will enroll both English and Spanish speaking participants into the study. All questionnaire outcomes will be translated into Spanish using conventional translational procedures and we will ensure that an interviewer at BIDMC is fluent in Spanish. It is important to emphasize that not all of the questionnaires used in this study have been validated in Spanish or with Hispanic patients. While this is an important limitation, we feel that this limitation is outweighed by the potential benefits of including primarily Spanish-speaking participants in the study.

The primary focus of the study is on assessing donor outcomes. The rationale for including the recipient is to examine the role that recipient factors play in predicting donor outcomes. There is preliminary evidence that some aspects of the recipient's functioning (e.g., graft survival, QOL) are associated with certain functional and psychological outcomes in living donors.7,8,88 The inclusion of transplant recipients in the study permits further examination of this association over time and allows us to include other recipient variables that heretofore have been neglected (e.g., perceptions of the donor-recipient relationship). Also, we will recruit a healthy, non-donor comparison group. A healthy comparison group allows us to address the question, "What if I had not donated my kidney?" - a question that is often considered by donors. These will be adults who completed one or more parts of the donor evaluation, but who did not proceed further for various reasons (although none of them medical).

C. Participant Recruitment and Retention

The first participant will be enrolled into the study in September 2011. Recruitment time is scheduled for 24 months. The last study assessment, therefore, will be completed in August 2015. Target recruitment for each site is 47 donor-recipient pairs and 27 healthy comparisons.

Importantly, we will recruit living donors into the study regardless of their recipient's participation status. Even in the absence of the recipient's participation, we will obtain valuable data about donor outcomes. However, because this is first-and-foremost a study evaluating donor outcomes, if a donor does not consent to participate in the study, we will not approach their recipient about study participation.

Non-directed donors will be recruited into the study. If it's an anonymous donation, their recipient will not be approached about the study. In the case, only the donor will be enrolled. If the non-directed donor has established a relationship (albeit a new one) with the intended recipient, then we will attempt to enroll both the donor and the recipient into the study, just like any other donor-recipient pair.

Donors participating in a paired kidney donation program (KPD) will be recruited into the study. In this instance, we will enroll KPD donors and their intended recipient (i.e., the recipient with whom they are incompatible, not the recipient of their specific kidney).

For each transplant recipient enrolled in the study, we will determine if s/he had other potential donors who were initially screened or evaluated but who did not progress to donation surgery. This initial screening or evaluation may include an initial health history, ABO testing, and/or other preliminary tests. To qualify as a control subject, the non-donor may or may not have completed the entire evaluation, but none of the studies performed will have excluded them from donation. If an enrolled donor has more than one potential health control subject, we will attempt to recruit them all into the study.