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

Over the past 15 years arthritis self-efficacy has emerged as one of the most important psychosocial variables in understanding pain and disability among people with rheumatoid arthritis (RA) (1-4). Self-efficacy refers to an individual's belief that they have the ability to successfully perform a certain behavior to achieve a desired outcome (5, 6). Self-efficacy is conceptualized as domain specific; that is, self-efficacy assesses one's confidence that they can perform a particular task (e.g. managing arthritis pain) rather than a global sense of control or mastery (7). Consistent with this conceptualization, Lorig et al. (8) developed an Arthritis Self-Efficacy Scale (ASES) to measure three key domains of arthritis self-efficacy: self-efficacy for pain control, self-efficacy to perform functional tasks, and self-efficacy to control other symptoms (i.e., fatigue, affect, remain active, enjoy activity). This standardized instrument has been shown to be reliable and is widely used to measure self-efficacy in psychosocial studies of RA patients (2, 3, 8-14). Research has shown that RA patients who report higher levels of self-efficacy experience less pain, physical disability, fatigue, and negative mood (8, 10, 15-17). Increases in self-efficacy that occur over the course of self-management training or pain coping skills training significantly predict improvements in RA pain, health status, and depression (11). Most rheumatologists focus on evaluating and reducing disease severity in order to reduce pain and disability. They are generally less focused on psychosocial factors, such as self-efficacy, that also potentially influence pain and disability. Likewise, many researchers who study self-efficacy have not sufficiently considered the effects of disease severity on self-efficacy. Given the recognized importance of both of these variables – disease severity and self-efficacy – it is critical to understand their relative relationship with RA outcomes. Further, a consideration of disease severity is especially important in RA because it potentially can influence both arthritis self-efficacy and RA outcomes. The current study used a structural equation model (SEM) to examine the relationships between disease severity, domains of arthritis self-efficacy, and measures of pain and functioning. SEM allows for simultaneous examination of the direct effects of disease severity and self-efficacy on measures of pain and function as well the degree to which self-efficacy explains observed relationships between disease severity and measures of pain and function (i.e., indirect effects). Our first hypothesis was that disease severity would have a direct relationship with pain and functioning; that is, patients with higher levels of disease severity would experience greater levels of pain and lower functioning. Our second hypothesis was that disease severity would have a direct relationship with self-efficacy; that is, RA patients with higher levels of disease severity would report lower self-efficacy across all self efficacy domains. Finally, we hypothesized that each type of domain specific self-efficacy would mediate the relationship between disease severity and its corresponding pain or functioning measure. Specifically, we predicted that self-efficacy for pain control would mediate the relationship of disease severity to ratings of pain and self-efficacy to perform functional tasks would mediate the relationship of disease severity to physical functioning. We also predicted that self-efficacy to control other symptoms would mediate the relationship between disease severity and both affective and social functioning because self-efficacy to control other symptoms (fatigue, activity regulation, feeling blue, manage pain during activities, manage pain to do things one enjoys, deal with frustration of pain) measures constructs that may be related to both affective (tension levels, mood) and social functioning (social activity, perceived social support).