Influence of individual illness perception on readiness to change behavior in patients with anorexia nervosa.

Background: Treating patients with anorexia nervosa (AN) is generally prolonged or often ineffective. A key factor influencing treatment is the high level of ambivalence patients feel regarding the necessary behavioral changes. We examined the trajectories of patients' readiness to change throughout their inpatient stay, considering the influence of their illness perceptions.

Methods: Data from clinical routine monitoring at the Department of Psychosomatic Medicine at Medical University Innsbruck, collected between 2015 and 2024, were analyzed. Monitoring included questionnaires assessing readiness to change (Fragebogen zur Erfassung der Veränderungsbereitschaft [FEVER], biweekly) and the patients' individual perception of illness (Brief Illness Perception Questionnaire [B-IPQ], weekly). Data analysis was conducted using linear mixed models, considering data from 189 adult patients (2321 data points) diagnosed with AN or atypical AN (F 50.0, F 50.1; 94.9% female; average length of hospital stay 5.3 weeks).

Results: Willingness to change shifted during treatment, with lower precontemplation and higher action scores at discharge. In linear mixed-effects models, higher perceived treatment control, illness concern, and consequences were significantly associated with more advanced stages of change.

Conclusion: The results indicate that an individual's perception of their illness influences their readiness to change. This underscores the importance of continuously integrating patients' perceptions into treatment and collaboratively addressing their assumptions and beliefs.