Photo Credit: iStock.com/DouglasOlivares

Negative affect and anxiety intensified the link between pain and reduced physical function in systemic sclerosis, suggesting a role for psychosocial interventions.

High levels of anxiety and negative affect worsened the effects of pain on the physical function of people with systemic sclerosis, according to findings recently published in the Journal of Scleroderma and Related Disorders.

“Although pain is recognized as a key contributor to impaired physical function in people with rheumatic and musculoskeletal diseases, research has identified additional important factors to consider,” wrote Daniel Whibley, PhD, and colleagues.

Previous research has identified factors linked with poorer physical function in autoimmune diseases like systemic sclerosis, such as female sex, older age, and higher fatigue, Whibley and colleagues explained.

“More recently, a study of 71 individuals with SSc highlighted significant associations between emotional status, pain, and function,” the researchers continued. “Furthermore, research in other chronic pain conditions has demonstrated that [the] association between pain intensity and functional outcomes may be dependent on level of self-efficacy, psychological distress, positive affect, severity of depressive and anxious symptoms, and resilience. Despite these intriguing data, the influence of psychosocial factors on the pain intensity-physical function association in people with systemic sclerosis remains understudied.”

Whibley and colleagues performed a cross-sectional study using data from a 12-week trial of digital fatigue self-management interventions. All patients were adults with systemic sclerosis.

At baseline, the researchers collected survey data that measured pain on an 11-point scale, as well as physical function using the PROMIS 4a short-form questionnaire. Dr. Whibley and colleagues also collected psychosocial data, including positive and negative affect as measured by the Positive and Negative Affect Schedule; resilience as measured by the Connor–Davidson Resilience Scale, anxiety and depression (evaluated with PROMIS short-forms); and self-efficacy domains using the PROMIS item banks.

Then, the researchers used linear regression analysis to quantify the relationship between pain and physical functioning scores after accounting for systemic sclerosis subtype, sex, and disease duration.

A total of 173 participants from the RENEW trial participated. The patients were an average of 54.5 years old (SD, 11.7, range, 26.6-87), and nearly all (93.1%) were women. The population was also mostly White (83.2%), and non-Hispanic or non-Latino (86.7%). About two-thirds were married (65%). Most patients (57.8%) had a college education or higher), and slightly less than half (42.8%) worked full or part-time at the time of the study. Patients were diagnosed a median of 4 years before the study began.

Nearly half of patients (47%) had diffuse cutaneous systemic sclerosis, whereas 35% had the limited subtype, 13% had overlapping subtypes, and 5% had other or “unsure” subtypes, the researchers reported.

Psychosocial Factors, Pain, & Function

Patients reported an average pain intensity of 4.9 (SD, 2.3) points out of 10, according to Dr. Whibley and colleagues, and the average reported physical function T-score was 38.5 (SD, 6.4). The researchers noted that this physical function score was 1.2 standard deviations below the national average score, which, they wrote, meant it was classified as a “moderate problem.”

Dr. Whibley and colleagues identified a linear association between pain intensity and physical function. After running regression diagnostic tests and adjusting for disease subtype, age, and disease duration, they reported that 31% of the variability in patients’ physical function was explained by the intensity with which they felt pain (unstandardized B = −1.34, 95% CI -1.69 to -0.99, P<0.001).

There were also statistically significant interactions between intensity of pain and both negative affect and anxiety, the researchers reported. Higher levels of pain, a more negative affect, and more anxiety appeared to intensify the negative association between pain and physical function.

Explaining the Link

“Negative affect and anxiety may adversely affect physical function due to alterations in motivation or avoidance behaviors,” Dr. Whibley and colleagues wrote. “Indeed, individuals managing both high levels of pain and affective distress may be vulnerable to lower motivation and adherence to tasks that are painful or challenging due to interruptions in directed attention or goal conflict (eg, pain relief vs rewarding approach behavior).”

People with chronic pain often adjust their lives to avoid pain, the researchers continued. However, this may avoid pain in the short term and worsen physical functioning in the long term.

“Our findings add to the growing body of evidence highlighting the negative association between pain intensity and physical function in systemic sclerosis, while also suggesting that negative affect and anxiety may modulate this association,” the researchers concluded, adding that interventions targeting psychosocial factors may help improve physical function regardless of pain severity.

“Future research could enhance understanding by examining whether managing pain effectively improves physical function in systemic sclerosis—although this may not be the case given several biomechanical drivers of poor physical function in systemic sclerosis,” they wrote.