Factor Structure and Effects of Illness Perception on Depression and Anxiety in Patients with Diabetes

Objective: Illness perception represents how a patient perceives his or her health and illness. The Brief Illness Perception Scale (BIPQ; Broadbent et al. 2006) is often used to assess illness perception. However, the factor structure of the BIPQ is inconsistent across studies. The present study aimed to confirm the factor structure of the BIPQ in diabetic patients and to examine its impact on depression and anxiety. Methods: Patients with diabetes (N = 340, type 1: 39. type 2; 296, others: 5) provided demographic and clinical information and completed the Japanese version of the BIPQ, the Patient Health Questionnaire-9, and the Generalized Anxiety Disorder -7. This research was conducted with the approval of Waseda University's Ethics Review Committee on Human Studies (Accreditation Number: 2021-351). Results: We eliminated one item on the timeline because of the ceiling effect. Then, we conducted an exploratory factor analysis and adopted a two-factor structure. Moreover, a confirmatory factor analysis with the same two-factor structure indicated the sufficient model fit (GFI = .93, AGFI = .86, CFI = .87) Furthermore, from multiple regression analyses, assessed the effects of "Impact on daily life" and "Sense of control", the two factors we named, on depression and anxiety indicated a significant coefficient of determination (R 2 = .31, p < .001, R 2 = .30, p < .001). Additionally, the Impact on daily life (β = .36, p < .01, β = .29, p < .01) and the Sense of control (β = - .29, p < .001, β = -.23, p < .001) had significant effects on depression and anxiety. Conclusion: The results supported the two-factor structure of the BIPQ, similar to that for cancer survivors (Hata et al., 2020), even though we eliminated one item. Illness perception in patients with diabetes consists of the impact of the disease on their daily lives and their sense of control over diabetes and its symptoms. Improving these perceptions would reduce depression and anxiety. Disclosure E. Tajima: None. K. Hata: None. S. Suzuki: None. Funding Japan Society for the Promotion of Science (19J22933)