Background/Purpose: Pain is a common symptom of systemic sclerosis (SSc), affecting over 80% of those living with the condition, with over a third experiencing pain of moderate or severe intensity. Pain intensity is strongly associated with physical functioning in SSc, however psychosocial moderators of this association are understudied. If modifiable psychosocial factors decouple the pain intensity-physical functioning association, addressing them may help diminish physical limitations attributable to SSc-related pain. Accordingly, this study examined psychosocial factors as potential moderators of the pain intensity-physical function association in SSc.

Methods: This cross-sectional observational study used baseline data from a trial examining the effectiveness of a web- and app-based intervention for fatigue management for people with SSc (ClinicalTrials.gov identifier NCT04908943). Participants were >18 years old with any SSc subtype, with a mean score >4 on the Fatigue Severity Scale. A questionnaire battery captured information about demographic, clinical and psychosocial factors. Pain intensity was assessed using the PROMIS Global Pain item (average pain past 7 days; 0-10 Numeric Rating Scale); physical function was assessed with the PROMIS short-form v2.0 Physical Function 4a. Psychosocial factors examined as potential moderators were positive and negative affect (Positive and Negative Affect Schedule), resilience (Connor-Davidson Resilience Scale), and PROMIS measures of anxiety, depression, fatigue, sleep disturbances, and self-efficacy. Linear regression was used to quantify the association between pain intensity and physical function, with interaction terms added for each moderator in separate models, adjusted for age, SSc subtype, and disease duration.

Results: Of 174 people recruited to the trial, 173 were randomized and included. 93% were female, sample mean age 54.5 (standard deviation (SD) 11.7). Most were white (83%), non-Hispanic/non-Latino (87%), and married (65%). 47% had diffuse cutaneous SSc, 35% limited,13% overlap, and 5% other/unsure. Mean (SD) pain intensity was 4.9 (2.3) and mean physical function T-score was 38.5 (1.2 SD below the general US population). There was a linear association between pain intensity and physical function, with pain intensity explaining 31% of variability in physical functioning, adjusted for age, SSc subtype, and disease duration. Statistically significant interaction effects were identified for level of negative affect, anxiety, and fatigue. In all cases, higher psychosocial symptom levels were associated with a stronger, negative association between pain intensity and physical functioning.

Conclusion: Negative affect, anxiety and fatigue moderated the association between pain intensity and physical functioning. Compared to those with lower levels of these psychosocial symptoms, those with higher levels experienced poorer physical functioning at higher pain intensities. If replicated, these findings would support longitudinal studies to examine whether addressing high levels of negative affect, anxiety and fatigue improve physical functioning of people with SSc-related pain.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/negative-affect-anxiety-and-fatigue-moderate-the-association-between-pain-intensity-and-physical-function-in-people-with-systemic-sclerosis/