Studies have found that illness perceptions explain significant variance in health outcomes in numerous diseases. However, most of the research is cross-sectional and non-oncological. We examined, for the first time in breast, colorectal and prostate cancer patients, if cognitive and emotional illness perceptions near diagnosis predict future multidimensional health-related quality of life (HRQoL).
UK-based patients (N = 334) completed the illness perception questionnaire-revised within 6 months post-diagnosis and the quality of life in adult cancer survivors scale 15 months post-diagnosis. Sociodemographic and clinical data were obtained from medical records. Hierarchical multiple regression analyses were conducted.
The sociodemographic and clinical factors collectively significantly predicted 8/12 HRQoL domains, although for 5/8 accounted for <10% of the variance. For all 12 HRQoL domains, illness perceptions collectively explained significant substantial additional variance (∆R(2) range: 5.6-27.9%), and a single illness perception questionnaire-revised dimension was the best individual predictor of 9/12 HRQoL domains. The consequences dimension independently predicted 7/12 HRQoL domains; patients who believed their cancer would have a more serious negative impact on their life reported poorer future HRQoL. The emotional representations and identity dimensions also predicted multiple HRQoL domains.
Future research should focus on realising the potential of illness perceptions as a modifiable target for and mediating mechanism of interventions to improve patients' HRQoL.