This study is an analytical observational retrospective cohort study. It is a single-center study conducted in the Nancy University Hospital.

End stage renal disease is the ultimate stage of the chronic kidney disease. Patients need extra-renal replacement techniques. Kidney transplantation is the most effective option for survival, quality of life and costs.

Then long-term immunosuppressive agents are required to prevent allograft rejection and improve graft survival.

The number of patients who return in dialysis after graft loss is increasing and accounts for 10% of incident dialysis patients and 14% of patients on the kidney transplant waiting list registered in 2019. This population may develop complications induced by end-stage renal disease and adverse events related to prolonged exposure to immunosuppressive agents.

There are currently no formal guidelines on the management of immunosuppressive agents when patients return to dialysis. Reduction or discontinuation of therapy appears to decrease cardiovascular, infectious, and neoplastic complications. However, continuing these treatments may limit anti-HLA sensitization which may access to retransplantation.

Only a few low-powered cohort studies have evaluated the impact of the management of immunosuppressive therapy on the HLA-sensitization.

The hypothesis of our study is that the continuation of immunosuppressive agents when patients return in dialysis may limit anti-HLA sensitization. Therefore, access to retransplantation could be facilitated.

The main objective is to compare the evolution of anti-HLA sensitization according to the management of immunosuppressive treatment after the return in dialysis (maintenance, reduction, cessation).

Secondary objectives are time to re-transplantation for patients on the transplant waiting list, survival of the new graft, patient survival, and dialysis complications (cardiovascular, infectious and neoplastic complications).

Cohort constitution :

The cohort of patients returning to dialysis after graft loss is extracted from the REIN (Réseau Epidémiologique et Information en Néphrologie) Lorraine registry, which follow all patients in end-stage renal failure under replacement therapy in the Lorraine region since 2001.

Patients returning to dialysis after graft loss between 1st January 2007 and 31st December 2019 are extracted from the register and included.

From this cohort, 3 groups were created according to the management of their immunosuppressive therapy : maintenance, reduction, and discontinuation. The immunological data of the patients are recovered from the HLA laboratory of the Nancy University Hospital.

Inclusion Criteria:

• Patients included in the Lorraine regional REIN registry over the period 2007-2019,
• Returning in dialysis after a kidney transplantation, with a living or deceased donor.
• On haemodialysis or peritoneal dialysis.
• Registered or not on the waiting-list for retransplantation

Exclusion Criteria:

• Patients with graft dysfunction receiving a pre-emptive retransplantation
• Absence of serum tested for anti-HLA (human leukocyte antigen) antibodies after the return to dialysis.
• No information on immunosuppressive agents

The cohort of patients returning to dialysis after graft loss is extracted from the REIN Lorraine registry. Patients returning in dialysis after graft loss between 1st January 2007 and 31st December 2019 are included.

From this cohort, 3 groups were created according to the management of their immunosuppressive therapy : maintenance, reduction, and discontinuation. The immunological data of the patients are recovered from the HLA laboratory of the Nancy University Hospital.