Illness Perception Mediation and Disease Characteristics Moderation of the Relationship Between Health Literacy and Self-Care Behaviors in Chronic Kidney Disease

Background: Health literacy (HL) is widely recognized as a determinant of self-care behaviors in chronic kidney disease (CKD). Grounded in the Common-Sense Model of Self-Regulation, illness perception may serve as a cognitive intermediary in this relationship, yet which specific dimensions carry this role in CKD remains unclear. Objective: This study examined the mediating roles of illness perception dimensions in the relationship between CKD-specific HL and self-care behaviors and explored how demographic and disease characteristics moderated this pathway. Methods: We conducted a cross-sectional study among 235 adults with CKD stage 3 or higher, recruited from the nephrology outpatient department of a regional hospital in central Taiwan. Participants completed validated measures of CKD-specific HL, illness perception across seven dimensions, and self-care behaviors. We performed mediation and moderated mediation analyses with 5,000 bootstrap samples. Results: HL was linked to three of the seven illness perception dimensions, namely timeline acute/chronic, personal control, and treatment control, while four dimensions—timeline cyclical, personal control, treatment control, and illness coherence—were related to self-care behaviors. Treatment control was the only dimension that mediated the relationship between HL and self-care behaviors; the other three dimensions did not. CKD duration moderated this mediating pathway. The indirect association between HL and self-care behaviors through treatment control was present among patients with shorter CKD duration but weakened and became non-significant as CKD duration increased. Discussion: Treatment control may be an important cognitive pathway linking HL to self-care in CKD. This pathway appeared more evident among patients with shorter disease duration, suggesting that HL-based support may be particularly useful when patients are still developing their understanding of CKD and confidence in treatment. For patients with a longer illness history, self-care support may need to move beyond information provision and address treatment confidence and the challenges of long-term disease management.