An exploration of the relationship between perceived injustice and pain severity in breast cancer survivors: a structural equation model

Abstract

Purpose The construct of perceived injustice is receiving increased attention in pain research due to its relationship with adverse pain outcomes. Even though cancer survivors face a 30% risk of developing pain, there is a notable lack of research exploring this relationship within this population. Therefore, this study aims to explore the relationship of perceived injustice with pain severity in breast cancer survivors (BCS). Methods A directed acyclic graph (DAG) (i.e., path model) was multidisciplinary created a priori, positioning perceived injustice -measured with the Injustice Experienced Questionnaire (IEQ)- as the main exposure variable and pain severity -measured with the Brief Pain Inventory (BPI)- as the main outcome variable, with the addition of explanatory variables within the relationship of IEQ and BPI. Data from 156 female BCS with pain and perceived injustice were analysed using structural equation modelling, with confidence intervals estimated through Montecarlo simulation. Results Perceived injustice did not have a significant univariate direct relationship with pain severity (beta = 0.186, p = 0.102). However, in the complete path model including explanatory outcomes, a significant relationship was observed (beta = 0.304, 95% CI [0.136; 0.477]), explaining 22,5% of the variance in pain severity. In the complete model, the greatest proportion of the effect was mediated through pain catastrophizing (beta = 0.226, 95% CI [0.101; 0.376]). Conclusion The findings indicate that perceived injustice has an important relationship with pain severity levels of BCS experiencing pain and perceived injustice. Multimodal intervention studies are suggested for future investigation as a treatment for pain in BCS.Registration prior to recruitment atClinicalTrials.gov NCT04730154.