The Dyadic Relationship of Illness Perception and Fear of Progression in Patients With Digestive System Cancers and Their Caregivers: An Actor‐Partner Interdependence Model Analysis

This study employs a dyadic analysis approach to explore the relationship between illness perception and fear of progression among digestive system cancer patients and caregivers using the Actor-Partner Interdependence Model (APIM). We selected 242 pairs of digestive system cancer patients and their primary caregivers from two tertiary hospitals in Guangdong Province using convenient sampling method. Participants completed the Brief Illness Perception Questionnaire and Fear of Progression Questionnaire. Structural equation modelling based on the APIM framework was used to assess both actor effects (individuals' illness perception on their own fear of progression) and partner effects (individuals' illness perception on the other member's fear of progression). This study included a total of 242 sets of participants, with patients having an average age of 55.97 (SD = 14.19) years and caregivers having an average age of 49.40 (SD = 13.18) years. The study revealed that the paired patterns of illness perception and fear of progression among patients and caregivers were couple patterns. Specifically, in terms of actor effects, illness perception among digestive system cancer patients and their caregivers was able to influence their own fear of progression (β = 0.238, 0.163; 95% CI = 0.167-0.310, 0.094-0.233; both p < 0.001). Regarding the partner effects, the illness perception of digestive system cancer patients and their caregivers positively influenced each other's fear of progression (β = 0.238, 0.163; 95% CI = 0.167-0.310, 0.094-0.233; both p < 0.001). This study confirms the existence of the actor-partner relationships between illness perception and fear of progression among digestive system cancer patients and their caregivers. These interdependent effects highlight the importance of adopting dyad-centred interventions in psycho-oncology care, where clinicians should address both patients and caregivers as an emotionally connected unit rather than isolated individuals.