Understanding immunosuppression medication adherence in kidney transplant recipients: a cross-sectional exploration of the role of illness perceptions, medication beliefs and perceived behavioural control.

Objective: Non-adherence to immunosuppression medication (ISM) is common in kidney transplant recipients (KTRs), despite being associated with poor clinical outcomes. Understanding potentially modifiable contributors to non-adherence is essential for developing effective interventions. This study explored the relationship between components of the Common-Sense Model (CSM), including illness perceptions (graft-specific and of kidney disease more broadly) and beliefs about ISM, as well as perceived behavioural control (PBC), and total, intentional and unintentional ISM non-adherence in KTRs. Methods and measures: A cross-sectional observational study was conducted with N = 296 KTRs. Participants completed self-report measures including the Brief Illness Perception Questionnaire, Beliefs about Medicines Questionnaire, questions assessing PBC, and the Medication Adherence Report Scale. Hierarchical binary logistic regression analyses were conducted to examine the explanatory value of variables on adherence outcomes. Results: Over half of participants (57%) reported any indication of non-adherence. Unintentional non-adherence was reported more frequently (54%) than intentional non-adherence (14%). Combining CSM components with PBC best explained variance in total (Nagelkerke R 2 = 19.8%), intentional (Nagelkerke R 2 = 15.5%), and unintentional non-adherence (Nagelkerke R 2 = 19.3%). Conclusion: Enhancing PBC around taking ISM may offer a valuable intervention target, particularly when addressed alongside CSM components to reduce both intentional and unintentional non-adherence.