Structural Relationships between Chronic Pain and Body Mass Index: The Mediating Role of Eating Behaviors and Components of the Fear-Avoidance Model

To investigate the structural relationships between chronic pain and body mass index mediated by eating behaviors, pain-related fear, anxiety sensitivity, and pain catastrophizing.

The research method was structural equation modeling and the statistical population of men and women with chronic pain referred to the orthopedic, physiotherapy, neurology wards of Al-Ghadir Hospital and orthopedic specialists of Farahbakhsh clinics in Tehran in spring, summer and autumn of 2022, of which 400 they were selected by purposive sampling method and participated in the research. Data were used to calculate participants' body mass index and the Dutch Eating Behavior Questionnaire (Van Strien, Frijters, Bergers & Defares, 1986), Chronic Pain (Vankorff et al, 1990), Pain Anxiety Symptom Scale (Pain-Related Fear) (McCracken & Dhingra, 2002), Anxiety Sensitivity Questionnaire (Patterson and Reese, 1992) and Pain Catastrophic Scale (Sullivan, Bishop, & Pivik, 1995) were collected and analyzed using structural equation modeling in Amos21 software.

The results showed that the model has a good fit with the observed data (df2c <3, GFI, AGFI and CFI> 0.90 and RMSEA <0.08). Chronic pain, pain-related fear, anxiety sensitivity, catastrophic pain, and eating behaviors can explain 29.6% of the variance in body mass index. 55.2% of the variance of eating behaviors is explained by chronic pain, pain-related fear, anxiety sensitivity, and catastrophic pain.

To prevent and treat obesity in people with pain, the variables of pain-related fear, anxiety sensitivity, catastrophic pain and eating behaviors should be targeted.