Outcomes in living kidney donors over 50 years compared to a healthy matched contemporaneous non-donor cohort from the same geographical region

Abstract A living kidney donor (LD) undergoes a major operation with potential risks of living with a single kidney. Studies comparing LDs with matched general population controls have found no differences in long-term outcomes between groups. However, recent studies comparing LDs to healthy matched controls have reported that LDs are at increased risk for end-stage kidney disease (ESKD), cardiovascular disease (CVD) and death. However, in these studies: the controls were not contemporaneous [born close to the same year]; not from the same geographic area; not known to be healthy on the date matching the donation date; and not matched for family history of ESKD. Each of these factors can impact the relative risk of developing kidney disease and its consequences. There are also concerns about the short follow-up and the statistical analyses of these studies. Some commentaries have suggested that the LD risk was under-estimated; others, overestimated. Having a complete and accurate understanding of true long-term LD risks is important to provide data to inform future LD candidates (informed consent), as well as to inform the design of long-term health maintenance of donors. Government agencies, providers, other stakeholders, and LDs themselves are asking for better quality long-term data. LDs at the University of Minnesota (U of MN) (1st transplant 1963), have been surveyed every 3 years, and data entered into a LD-specific database. Using the Rochester Epidemiology Project (REP), we optimally matched the LDs with healthy controls. The REP includes data as early as the 1950 and established a linked medical records system that has followed the medical history of residents of Olmsted County (same geographic area as the U of MN and Mayo Clinic). LDs were matched with contemporaneous healthy REP controls on age, gender, race/ethnicity. Matched controls then had medical chart review to ensure health at the time corresponding to the donation date. Chart-validated controls had data entered into a designated database; and were sent a survey, similar to the U of MN LD survey, asking about current health. In addition, data has been collected on Mayo Clinic LDs and matched controls. For all LDs and matched controls, data has been supplemented by information from the NDI (death), Minnesota State (death) and USRDS (ESKD). With this grant, we will use our comprehensive dataset to compare long-term (>40 yrs) outcomes of LDs and controls. Because of the quality of the data in the LD and REP datasets, we will be able to study and provide the best data to date on: LD risk of ESKD and death; risk of the more common intermediate events that precede ESKD or death (e.g., CVD); the impact of known risk factors such as family history or smoking on donation risk; the impact of post-donation new onset disease (e.g., diabetes) on risk; and the impact of donation on subsequent pregnancies. We will provide the most comprehensive data, to date, to inform prospective LDs about long-term risk, and to inform the follow-up and care of current LDs.