RESUMO
Irritable bowel syndrome (IBS) is the most common gastrointestinal (GI) condition treated by GI and primary care physicians. Although IBS symptoms (abdominal pain, bowel problems) are generally refractory to medical therapies, consistent research has shown that they improve following cognitive-behavioral therapy (CBT). Notwithstanding empirical support for CBT, there is less research explicating the reasons for why or how it works. Like other pain disorders, the focus on change mechanisms for behavioral pain treatments has focused on pain-specific cognitive-affective processes that modulate pain experience, few of which are more important than pain catastrophizing (PC). The fact that PC changes are seen across treatments of differing theoretical and technical orientation, including CBT, yoga, and physical therapy, suggests that it may be a nonspecific (vs. theory-based) change mechanism akin to therapeutic alliance and treatment expectancy. Therefore, the current study examined change in PC as a concurrent mediator of IBS symptoms severity, global GI symptom improvement, and quality of life among 436 Rome III-diagnosed IBS patients enrolled in a clinical trial undergoing two dosages of CBT versus a nonspecific comparator emphasizing education and support. Results from structural equation modeling parallel process mediation analyses suggest that reduction in PC during treatment are significantly associated with improvement in IBS clinical outcomes through 3-month follow-up. Results from the current study provide evidence that PC may be an important, albeit nonspecific change mechanism, during CBT for IBS. Overall, reducing the emotional unpleasantness of pain through cognitive processes is associated with improved outcomes for IBS.