Der Einfluss von subjektiven Krankheitstheorien auf Demoralisierung, Depression und Angst bei Patienten mit einer Krebserkrankung: eine Längsschnittstudie

Background The aim of this longitudinal study was to examine the impact of illness perceptions on the longitudinal change of demoralization, depression, and anxiety in patients with cancer.

Method We assessed n=307 patients with mixed tumor entities at three time points. T1 was conducted on occasion of in- or outpatient treatment, T2 at 6-month follow-up (n=213, 69%), and T3 at 12-month follow-up (n=153, 50%). Subjective perceptions of illness were assessed using the subscales consequences, personal control, treatment control, and illness coherence of the Illness Perception Questionnaire-Revised (IPQ-R). We assessed psychological distress using the Demoralization Scale (DS), the Patient Health Questionnaire-9 (PHQ-9), and the General Anxiety Disorder Scale-7 (GAD-7). Longitudinal analyses were conducted using repeated measures analysis of variance (MANOVA).

Results At baseline, 20% of the participants perceived cancer-related significant consequences (12-month follow-up: 16%); 25% reported a sense of personal control (12-month follow-up: 17%); 42% perceived their illness as something that could be controlled through treatment (12-month follow-up: 26%), and 24% perceived their illness as subjectively coherent (12-month follow-up: 30%). The perception of relevant consequences was associated with significantly higher levels of psychological distress; controllability and coherence were associated with significantly lower levels of psychological distress. The size of this association was highest for demoralization: (consequences: r=0.45, p<0.001, personal control: r=− 0.25, p<0.001, treatment control: r=− 0.31, p<0.001, coherence: r=− 0.27, p<0.001). None of the subscales had a significant impact on the change of psychological distress over the course of 12 months (d≤0.29, p≥0.09).

Discussion Subjective illness perceptions in terms of significant consequences, uncontrollability and incomprehensibility are related to current high levels of distress in patients with cancer. Such perceptions are not necessarily associated with a further increase in psychological distress over time. One possible explanation is the limited ability of the IPQ-R to differentiate adaptive-adequate from maladaptive-distorted illness perceptions.