Disease severity and domain-specific arthritis self-efficacy: relationships to pain and functioning in patients with rheumatoid arthritis

Abstract

Objective: To examine the degree to which disease severity and domains of self-efficacy (pain, function, and other symptoms) explain pain and functioning in rheumatoid arthritis (RA) patients.

Methods: Patients (n = 263) completed the Arthritis Impact Measurement Scales 2 to assess pain and functioning (physical, affective, and social), the Arthritis Self-Efficacy Scale to assess 3 self-efficacy domains (pain, physical function, and other). Disease severity was assessed with C-reactive protein level, physician's rating, and abnormal joint count. Structural equation modeling was used to examine 3 hypotheses: does disease severity have a direct relationship with pain and each area of functioning, does disease severity have a direct relationship with each arthritis self-efficacy domain, and do the self-efficacy domains mediate the relationship between disease severity and RA pain and each area of functioning.

Results: Disease severity was related to pain, physical functioning, and each self-efficacy domain (beta = 0.28-0.56, P < 0.001). Each self-efficacy domain was related to its respective domain of functioning (e.g., self-efficacy for pain was related to pain; beta = 0.36-0.54, P < 0.001). Self-efficacy mediated the relationship between disease severity and pain and functioning (beta = 0.12-0.19, P < 0.001). Self-efficacy for pain control and to perform functional tasks accounted for 32-42% of disease severity's total effect on their respective outcomes (e.g., self-efficacy for pain control accounted for 32% of disease severity's total effect on pain). Variance accounted for by the total model was 52% for pain, 53% for physical functioning, and 44% for affective and social functioning.

Conclusion: Disease severity and self-efficacy both impact RA functioning, and intervening in these areas may lead to better outcomes.

Trial registration: ClinicalTrials.gov NCT00088764.

Figures

Figure 1

Note. Structural Equation Model; Fit Indices:; CFI = 0.96;; RMSEA = .06 (90% CI = 0.047-0.074); SRMSR = .04. Age, education, race, and opioid use are controlled for in the model. Direct paths were specified between control variables and disease severity, self-efficacy variables, pain, physical function, affective function, and social function. These paths are not displayed in the figure for ease of readability. All paths displayed in the figure are significant except disease Severity to Affective Function and Disease Severity to Social Function.