Introduction: Kidney transplantation (KT) is the treatment of choice for patients with End-Stage Kidney Disease (ESKD), as it is associated with improved quality-of-life and cost-effectiveness when compared to dialysis, regardless of age. Young adult kidney transplant recipients (YKTR) have the highest rate of graft loss amongst transplant recipients in the UK and have been consistently identified as a high-risk group for immunosuppression non-adherence. YKTR face unique challenges, including transition from paediatric to adult care and developmental brain changes, which have been shown to impact adherence. Importantly, non-adherence after KT is a major risk factor for poor patient/graft outcomes.
Published research has focused on clinical and demographic predictors of non-adherence in YKTR. Psychological factors, including medication beliefs and illness perceptions, which are potentially amenable to change, have also been implicated. However, these factors are poorly understood and have not been fully interrogated.
The purpose of this study was i) to catalogue the prevalence of non-adherence in a cohort YKTR (aged 18-25 years) and investigate associations of non-adherence with psychological factors and ii) to undertake a comparative analysis of findings in a cohort of KTR aged over 25 years. 
Method: Patients attending clinic between 24/11/2016 and 23/08/2023 completed electronic self-report questionnaires, including (i) Medication Adherence Report Scale, (ii) Beliefs about Medicines Questionnaire-Specific and (iii) Brief Illness Perception Questionnaire. Analyses were conducted using Mann-Whitney U and t-tests i) within the YKTR cohort ii) between YKTR and KTR aged >25 years who completed the same questionnaire measures between 21/09/2022 and 20/03/2023.
Results: Of n=35 YKTR, n=24 (68.6%) were classed as non-adherent overall, n=23 (65.7%) unintentionally non-adherent and n=9 (25.7%) intentionally non-adherent. Intentionally non-adherent YKTR reported significantly greater medication concerns, t(33)=2.71, p=.005, lower personal control, t(33)=2.252, p=.031 and lower treatment control, Z=-2.61, p=.009, compared with adherent YKTRs. Compared with KTRs aged >25 years, YKTR had significantly lower perceived consequences of the health of their transplant on their life, Z=-2.670, p=.008.
Conclusion: Rates of overall non-adherence in our YKTR cohort are consistent with existing literature. Reported rates of intentional non-adherence were high. Importantly, we identified that medication beliefs and illness perceptions significantly affect IS adherence in YKTR. These psychological factors may be amenable to change through intervention. Reducing medication concerns and enhancing personal and treatment control may reduce intentional non-adherence. Additionally, perceptions of consequences may be a specific intervention target for YKTR. Further research to design and implement tailored interventions is essentiale, considering the unique challenges faced by YKTR.