Background: Advanced treatment options have resulted in more women surviving breast cancer. However, breast cancer treatment is often associated with negative side-effects, which can impact on survivors’ quality of life. Chronic pain is a recognised long-term consequence associated with breast cancer and its treatment, and is reported by 25-60% of breast cancer survivors. Chronic pain experienced by breast cancer survivors is often underdiagnosed and undertreated. Research attempting to understand the underlying mechanisms of chronic pain in breast cancer survivors is inconclusive. Illness representations have been used to predict a number of illness outcomes experienced by a range of different health conditions including breast cancer; however, there are no current studies that have used illness representations to understand chronic pain experienced by breast cancer survivors. The aim of the current study was to explore the association between illness representations, health-related quality of life (HRQoL) and chronic pain in women who have survived breast cancer.
Methods: A cross-sectional online survey design was used. Data from 182 women who participated in the survey were analysed. Participants provided demographic and illness-related information. Illness representations were assessed using the Illness Perception Questionnaire - Revised (IPQ-R); pain was assessed by the Brief Pain Inventory – Short Form (BPI-SF); HRQoL was assessed by the EuroQol – visual analogue scale (EQ-VAS); and, depression and anxiety were measured using the Patient Health Questionnaire – 8 items (PHQ-8) and the Generalised Anxiety Disorder scale – 7 items (GAD-7), respectively. Ordinal logistic regression models were used to quantify the relationship between illness representations, HRQoL and pain, adjusted for demographics, illness-related and psychological (e.g. anxiety and depression) factors.
Results: Chronic pain was reported by 66% of respondents. Using the BPI-SF, participants were categorised into one of four pain categories: no pain (34.1%); mild pain (35.7%); moderate pain (25.3%) and severe pain (4.9%). Of the illness representation dimensions, timeline (acute/chronic), consequences, timeline (cyclical), treatment control and causal factors (stress and state of health), were significantly associated with pain severity. Having a strong illness identity (IPQ-R subscale which assesses the number of symptoms an individual attributes to their illness) was found to be a significant predictor of pain severity (OR 1.21, (95% CI 1.07-1.37), p=0.003). The results also found that HRQoL was significantly associated and predictive of pain severity (OR 0.97, (95% CI 0.95-0.99), p<0.001). An additional finding was that not being in paid work was strongly associated with being in a higher pain category (OR 5.92, (95% CI 1.84-19.05), p=0.003).
Discussion: The findings of this study show that dimensions of illness representations are associated with chronic pain experienced by breast cancer survivors. However, results from the logistic regression analysis showed that in a fully adjusted model, only the IPQ-R identity domain remained an independent predictor of chronic pain, along with reduced HRQoL and not being in paid work. Furthermore, the high prevalence of chronic pain reported in this study highlights an important unmet clinical need, whereby breast cancer survivors are not receiving adequate pain management, resulting in reduced HRQoL associated with a high prevalence of moderate to severe pain. These findings have made a contribution to existing research which has attempted to understand chronic pain experienced by this population. These findings should be used to inform future research and clinical practice, which could result in better prevention, assessment and management of pain experienced by breast cancer patients and/or survivors.
