Processes mediating the relation between pain catastrophizing and pain outcomes
The literature reviewed in this chapter points to several processes or mechanisms that might underlie the relation between pain catastrophizing and pain outcomes. Research suggests that pain catastrophizing is significantly associated with expectancies for heightened pain experience, increased attention to pain sensations and increased negative mood. In turn, expectancies, attention and negative mood have been shown to contribute to heightened pain experience. Research also suggests that pain catastrophizing might interfere with the effectiveness of certain coping strategies and might be associated with strategies (e.g. distress displays) that inadvertently contribute to increased pain.
It is important to caution that observed relations between pain catastrophizing and expectancies, attention, negative mood and coping cannot be taken as evidence that these are the processes by which pain catastrophizing impacts on pain experience. In order to determine which of these variables underlie the relation between pain catastrophizing and pain outcomes, it is necessary to examine the degree to which the catastrophizing-pain relation is diminished when controlling, experimentally or statistically, for potential determinants (or mediators).
Unfortunately, few studies have conducted mediational analyses for variables that might underlie the relation between pain catastrophizing and pain outcomes. Still, the available research permits some speculation about potential mediational candidates. Research addressing the role of expectancies in mediating the relation between pain catastrophizing and pain has yielded mixed findings. Sullivan et al. (2001a) reported that expectancies for pain experience prior to an experimental pain procedure partially mediated the relation between catastrophizing and pain. In a recent study of patients with osteoarthritis, Shelby et al (2008) reported that self-efficacy fully mediated of the relation between catastrophizing and pain in patients with osteoarthritis.
The research on the relation between pain catastrophizing and attention to pain is strongly suggestive that attention might mediate the catastrophizing-pain relation. Catastrophizing appears to be associated with a propensity to focus excessively on pain, and might also be associated with a deficit in mental control over pain-related stimuli such that individuals high in catastrophizing will have more difficulty disengaging their attention from a pain stimulus. Although the bulk of this research has been conducted within experimental paradigms, there is little basis for arguing that different processes might operate in patients with chronic pain. In chronic pain patients, pain catastrophizing has been shown to correlate significantly with self-reported vigilance to pain symptoms (Crombez et al. 2004). Surprisingly, research suggests that pain catastrophizing might mediate the relation between vigilance and pain, as opposed to vigilance mediating the relation between pain catastrophizing and pain (Crombez et al. 2004).
Questions concerning the role of emotional distress as a mediator of the relationship between catastrophizing and pain have been addressed in several investigations. Overall, the findings of this research do not support the mediating role of emotional distress. Many investigations have reported findings suggesting that instead of emotional distress mediating the relation between pain catastrophizing and pain outcomes, pain catastrophizing might mediate the relation between emotional distress and pain. Geisser et al. (1995) found that pain catastrophizing mediated the relation between depression and pain. Lackner and Quigley (2005) reported that pain catastrophizing mediated the relation between worry and pain in individuals with irritable bowel syndrome. In a study using experimental pain and mood induction, Bartley and Rhudy (2008) found no evidence that pain catastrophizing exerted its effects on pain indirectly through mood.
Thus, it appears that emotional distress might not be a promising candidate as a mediator of the relation between pain catastrophizing and pain outcomes. Although emotional distress co-varies with catastrophic thinking to a significant degree, the research does not support the view that emotional distress is the vehicle through which pain catastrophizing exerts its impact on pain outcomes.
The role of coping as a mediator of the relation between catastrophizing and pain outcomes has been more challenging to address. First, the use of ‘adaptive’ coping strategies does not appear to co-vary with level of pain catastrophizing, although the effectiveness of coping strategies might be influenced by level of pain catastrophizing. It is possible that pain catastrophizers might use maladaptive strategies, such as the expression of pain behaviour, that inadvertently contribute to adverse interpersonal or pain outcomes. However, if the use of pain behaviour to solicit attention or support is not driven by conscious intent, it will be difficult to establish whether such coping efforts are the process by which pain catastrophizing impacts negatively on pain outcomes.