Risk Factors and Patterns of Acute and Chronic Rejection in Pediatric Kidney Transplant Recipients in Saudi Arabia: A Retrospective Analysis.

BACKGROUND: Acute rejection (AR) in pediatric kidney transplantation (KT) cases in Saudi Arabia are not well documented. Our study investigated AR in pediatric patients and identified risk factors for acute and chronic allograft rejection in pediatric population. METHODS: This retrospective study included all pediatric patients aged 1-17 years who underwent KT at a specialized hospital in Riyadh, Saudi Arabia, between September 2005 and June 2022. Included patients were categorized into two groups (AR and control) based on the occurrence of biopsy-proven rejection. RESULTS: In total, 49/174 (28.2%) patients had pathologically confirmed AR, whereas 12/174 (6.9%) experienced chronic rejection. The most common type of rejection was T cell-mediated rejection TCMR (41/49 [83.7%]), followed by mixed rejection (TCMR and antibody-mediated rejection ABMR; 7/49 [14.3%]) and ABMR (1/49 [2%]). Patients experiencing multiple rejection episodes were older (median age: 10 years; IQR: 7-11) compared to those with a single episode (median age: 7 years; IQR: 3-10) and those with no rejection episodes (median age: 6 years; IQR: 4-9) (p-value = 0.0012). Children aged >5 years had triple the risk of AR (hazard ratios (adjusted HR = 3.18, p-value =0.001); however, multiple opportunistic infections increased the risk of rejection by 2-fold (aHR = 2.31, p-value =0.029). CONCLUSIONS: This study confirmed the importance of recipient age at the time of surgery and the significance of monitoring transplantation for rejection markers and infections as they can considerably affect graft and patient survival.