Chronic kidney disease is a condition that affects over 800 million people worldwide, with about 0.1% of the world population suffering from end-stage kidney disease (ESKD) [1]. From the second half of the twentieth century, kidney transplantation has become the kidney replacement therapy of choice for ESKD, improving both mortality and quality of life. [2]. However, this approach collides with the persistent shortage of organs available worldwide. As of 2021 in the United States, there were 90,483 ESKD patients on the waiting list for a kidney transplant, but only 24,670 were effectively transplanted [3]. Portugal is the European country with the highest prevalence of ESKD, mainly related to high incidence of diabetes mellitus and hypertension [4]. On January 2022, there were 20,731 patients with ESKD in Portugal, with an estimated prevalence of 0.2%. Forty of the 2872 patients waiting for a transplant died while the waiting list [5].

As most of renal grafts are retrieved from brain dead donors, efforts are being made to increase availability, using circulatory death donors as a legitimate source of organ donation. Donation after circulatory death (DCD) can be divided into four categories according to the Modified Maastricht Classification [6] Maastricht type 2 and Maastricht type 3 donation are the most frequent categories used worldwide. Maastricht type 2 or uncontrolled DCD donation refers to donors who suffered sudden, unexpected and witnessed cardiac arrest, with unsuccessful resuscitation efforts. Maastricht type 3 or controlled DCD donation refers to donors in whom there is a planned withdrawal of life sustaining therapy followed with expected cardiac arrest [6]. In Portugal only Maastricht type 2 donation programs have been approved. These programs were put into place in 2017, after criteria for cardiocirculatory death were established by law in 2013. Maastricht type 3 donation is yet to be approved.

It is important to access the impact of these programs in both the short- and long-term renal graft function. This study aims to evaluate the factors influencing the short-term outcome of renal organ transplantation from Maastricht type 2 donation as well as early graft function.