Incremental validity of psychological acceptance over pain intensity and catastrophizing to predict adjustment in females with endometriosis

Background: While there is substantial evidence supporting acceptance of pain as a protective factor for a positive adjustment to chronic pain, few research exists about the contribution of general acceptance (i.e., the ability of accepting not only pain but also other internal events such as difficult thoughts and feelings) to explain adjustment to chronic pain. The present study explored the incremental validity of general acceptance to predict adjustment to pain in females with endometriosis, over and beyond the effect of two well-known predictors of adjustment (pain intensity and catastrophising). Methods: Participants were 519 females with endometriosis and illness-related pain, aged between 18-56 years (mean age = 34.6; SD = 6.26). Participants were recruited through the Italian Association for the Endometriosis Project (AEP). Participants completed self-report measures of pain intensity, catastrophizing, general acceptance, functioning, psychological well-being, anxiety, and depression. Results: The results from Hierarchical Regression Analyses showed that the contribution of general acceptance was statistically significant over and beyond socio-demographic variables, pain intensity and catastrophizing. The percentage of additional explained variance ranged from 3% (for functioning) to 28% (for psychological well-being) across the outcomes. Conclusion: Findings support the unique role of psychological acceptance above and beyond pain intensity and catastrophizing in predicting pain adjustment in patients with endometriosis. These findings suggest that psychological interventions may improve their effectiveness by fostering broader acceptance abilities that allow patients to accept not only pain but also other difficult inner experiences.