The Mediating Effect of Perceived Injustice and Pain Catastrophizing in the Relationship of Pain on Fatigue and Sleep in Breast Cancer Survivors: A Cross-Sectional Study.

OBJECTIVE: Multidimensional aspects of pain have raised awareness about cognitive appraisals, such as perceived injustice (PI) and pain catastrophizing (PC). It has been demonstrated that they play an important role in patients' pain experience. However, the mediating effect of these appraisals has not been investigated in breast cancer survivors (BCS), nor have they been related to fatigue and sleep. METHODS: Cross-sectional data from 128 BCS were analysed by structural path analysis with the aim to examine the mediating effect of PI and PC in the relationship of pain on fatigue and sleep. RESULTS: The indirect mediating effects of PI on fatigue (CSI*PI = 0.21; P < .01 and VAS*PI = 1.19; P < .01) and sleep (CSI*PI = 0.31; P < .01 and VAS*PI = 1.74; P < .01) were found significant for both pain measures (Central Sensitization Inventory [CSI] and Visual Analogue Scale [VAS]). PC, on the other hand, only mediated the relationship between pain measured by VAS and fatigue (VAS*PC = 0.80; P = .03). Positive associations were found, indicating that higher pain levels are positively correlated with PI and PC, which go hand in hand with higher levels of fatigue and sleep problems. CONCLUSIONS: PI is an important mediator in the relationship of pain on fatigue and sleep, while PC is a mediator on fatigue after cancer treatment. These findings highlight that both appraisals are understudied and open new perspectives regarding treatment strategies in BCS.

Prevalence and risk factors of sleep disturbances in breast cancersurvivors: systematic review and meta-analyses.

BACKGROUND: Breast cancer remains the most frequently diagnosed malignancy among women worldwide, with rising incidence numbers. In Belgium, one out of eight women will be diagnosed with breast cancer. Fortunately, 80% of those breast cancer patients will still be alive 10 years after diagnosis due to improvements in screening and treatment strategies. However, an important portion of the breast cancer survivors (BCS) will face side effects, such as sleep disturbances, long after treatment ends. It has been demonstrated that untreated insomnia in BCS negatively impacts mood, physical symptoms, pain sensitivity, fatigue, and quality of life. Furthermore, insomnia is increasingly considered an independent risk factor for future depression in BCS. The importance of understanding sleep disturbances in cancer populations has been highlighted and recognized as warranting further research. Therefore, the purpose of this systematic review was to determine the prevalence and the risk factors for the development of sleep disturbances in BCS. METHODS: PubMed, Web of Science, and PEDro were systematically screened for studies encompassing data regarding the prevalence or risk factors of sleep disturbances in BCS. If possible, meta-analyses were performed. Subgroup analyses were undertaken based on the methodological quality, study design, type of sleep disturbance, and the use of a measurement tool with strong psychometric properties to investigate significant heterogeneity (I2 > 50%) across studies. RESULTS: A total of 27 studies were found eligible. The pooled estimate for sleep disturbances prevalence is 0.40 (95% confidence interval (CI) = [0.29-0.52], I2 = 100%, p < 0.00001) and ranged from 0.14 (95% CI = [0.04-0.24]) to 0.93 (95% CI = [0.91-0.95]). Subgroup analyses did not reduce the heterogeneity among studies. Meta-analyses were performed for seven risk factors. Significant differences for the odds of developing sleep disturbances were found for hot flashes (pooled OR (ORp) 2.25, 95% CI = [1.64-3.08], I2 = 0%, p = 0.90), race (ORp 2.31, 95% CI = [1.56-3.42], I2 = 0%, p = 0.47), and menopause (ORp 1.84, 95% CI = [1.11-3.06], I2 = 0%, p = 0.70). After withdrawing the studies that did not rely on the use of a measurement tool with strong psychometric properties, pain (ORp 2.31, 95% CI = [1.36-3.92], I2 = 27%, p = 0.25), depressive symptoms (ORp 3.20, 95% CI [2.32-4.42], I2 = 0%, p = 0.63), and fatigue (ORp 2.82, 95% CI = [1.98-4.02], I2 = 0%, p = 0.60) became significant as well, with a substantial decrease of heterogeneity. CONCLUSION: Prevalence for sleep disturbances ranged from 0.14 to 0.93 with the vast majority of the studies investigating insomnia and sleep-wake disturbances. High heterogeneity makes it difficult to draw firm conclusions. Pain, depressive symptoms, hot flashes, fatigue, non-Caucasian race, and menopausal status were significantly associated with increased odds for developing sleep disturbances.