Evolution of kidney allograft loss causes over 40 years (1979-2019).

Introduction: The improvement of kidney allograft recipient and graft survival showed a decrease over the last 40 years. Long-term graft loss rate remained stable during a 25-year time span. Knowing the changing causes and the risk factors associated with graft loss requires special attention. The present study aimed to assess the causes of graft loss and kidney allograft recipient death. Also, we aimed to compare two different periods (1979-1999 and 2000-2019) to identify changes in the characteristics of the failed allografts and recipient and donors profile.

Methods And Patients: We performed a single-center cohort study. We included all the kidney transplant recipients at the Hospital del Mar (Barcelona) between May 1979 and December 2019. Graft loss was defined as recipient death with functioning graft and as loss of graft function (return to dialysis or retransplantation). We assessed the causes of graft loss using clinical and histological information. We also analyzed the results of the two different transplant periods (1979-1999 and 2000-2019).

Results: Between 1979 and 2019, 1522 transplants were performed. The median follow-up time was 56 (IQR 8-123) months. During follow-up, 722 (47.5%) grafts were lost: 483 (66.9%) due to graft failure and 239 (33.1%) due to death with functioning graft. The main causes of death were cardiovascular (25.1%), neoplasms (25.1%), and infectious diseases (21.8%). These causes were stable between the two periods of time. Only the unknown cause of death has decreased in the last period. The main cause of graft failure (loss of graft function) was the allograft chronic dysfunction (75%). When histologic information was available, antibody-mediated rejection (ABMR) and interstitial fibrosis/tubular atrophy (IF/TA) were the most frequent specific causes (15.9% and 12.6%). Of the graft failures, 213 (29.5%) were early (<1 year of transplantation). Vascular thrombosis was the main cause of early graft failure in the second period (2000-2019) (46.7%) and T-cell-mediated rejection (TCMR) was the main cause (31.3%) in the first period (1979-1999). The causes of late graft loss were similar between the two periods.

Conclusions: The causes of kidney allograft recipient death are still due to cardiovascular and malignant diseases. Vascular thrombosis has emerged as a frequent cause of early graft loss in the most recent years. The evaluation of the causes of graft loss is necessary to improve kidney transplantation outcomes.