Exploring the contribution of illness perceptions to psychological distress among breast cancer survivors

Abstract

Breast cancer patients are increasingly becoming long-term cancer survivors. However, the physical and psychosocial sequelae of the cancer diagnosis and its treatment may persist long after the completion of active treatments. Leventhal’s common-sense model proposes that individuals’ illness perceptions influence their illness outcomes. Hence, it is crucial to understand how Chinese breast cancer survivors perceive their illness and explore the contribution of their illness perceptions to long-term psychological distress. This thesis has four objectives: 1) to assess the psychometric properties of the measure of illness perceptions in a sample of Chinese breast cancer survivors; 2) to describe illness perceptions among Chinese breast cancer survivors and its related factors; 3) to examine the contribution of illness perceptions to change of psychological distress over the first year after the completion of active treatment, and 4) to explore the indirect effect of illness perceptions on psychological distress through physical symptom burden. 372 breast cancer survivors were consecutively recruited within 6 months of completion of active treatment (baseline) from Hong Kong public hospitals and followed up at 3-months, 6-months, and 12-months post-baseline. Patients’ illness perceptions, psychological distress, physical symptom burden, health-related information needs, dispositional optimism, demographics and clinical chracteristics were assessed by standardised and valid questionnaires. Three studies were conducted to accomplish each proposed objective. Study I was a validation study that assessed the psychometric properties of Brief Illness Perception Questionnaire (B-IPQ). Study II was a cross-sectional study that examined illness perceptions of Chinese breast cancer survivors and correlates. Study III was a longitudinal-study exploring the contribution of illness perceptions to the change of psychological distress as well as the mediation effect of physical symptom burden on the relationship between illness perceptions and psychological distress. Study I suggested that after deleting one item measuring illness coherence, sevenitems gave an optimal two-factor (cognitive-emotional representations) structure for the B-IPQ (B-IPQ-7). Cronbach’s alpha for the two subscales were 0.653 and 0.821. Correlations of illness perceptions and physical symptom distress, anxiety, depression and known-group comparison between different treatment status suggested acceptable construct validity. The association between baseline illness perceptions and psychological distress at 3-month follow-up supported predictive validity. Study II revealed that breast cancer survivors’ cognitive and emotional representations of illness were inter-correlated. Stress-related factors were the most frequently attributed causes of cancer. Patients who were at a younger age, had undergone adjuvant chemotherapy and radiotherapy, had lower level of dispositional optimism, more health-related information needs, and presence of more physical symptoms experienced more negative illness perceptions. Study III indicated that more negative cognitive representations of illness at baseline predicted greater anxiety at 12 months follow-up, and more emotional representations of illness at baseline predicted slower rate of decline in depression over the 12 months follow-up. This study provides insights into the factorial structure of illness perceptions, how Chinese breast cancer survivors who have finished their active treatment perceive their illness, and the correlates of their illness perceptions. It also helps understanding whether illness perceptions at transitional period predict changes of anxiety and depression over time.