Psychosocial moderators of the association between pain intensity and physical function in people with systemic sclerosis

Abstract

Background:

Pain is a prevalent symptom of systemic sclerosis. While previous studies have demonstrated a correlation between higher pain intensity and lower physical function in individuals with systemic sclerosis, the potentially moderating effect of psychosocial factors on the association has yet to be explored.

Methods:

This cross-sectional study used data from a fatigue self-management trial for adults with systemic sclerosis. Baseline questionnaire instruments measured pain intensity (11-point scale), physical function (PROMIS 4a short form), and psychosocial factors: positive and negative affect (Positive and Negative Affect Schedule), resilience (Connor–Davidson Resilience Scale), anxiety, depression (PROMIS short forms), and self-efficacy domains (PROMIS item banks). Linear regression quantified the pain intensity–physical function association with interaction terms for candidate psychosocial moderators included in separate models (adjusted for age, systemic sclerosis subtype, and disease duration).

Results:

Among 173 participants (mean age 54.5, Standard Deviation 11.7, 93% female, 83% White), 47% had diffuse cutaneous systemic sclerosis, 35% limited, 13% overlap, and 5% other/unsure. Mean pain intensity was 4.9 (Standard Deviation 2.3) and mean physical function T-score was 38.5 (Standard Deviation 6.4). Pain intensity accounted for 31% of the variability in physical function (B −1.34, 95% confidence interval −1.69, −0.99). Statistically significant interactions were found between pain intensity and negative affect and anxiety, with higher levels of these factors amplifying the negative pain–physical function association.

Conclusion:

These findings suggest that higher levels of negative affect and anxiety exacerbate the negative effect of pain on physical function in individuals with systemic sclerosis. Interventions targeting these factors may help improve overall physical function regardless of pain intensity.