McCracken, L. M. and K. E. Vowles (2008). "A prospective analysis of acceptance of pain and values-based action in patients with chronic pain." Health Psychol 27(2): 215-20.  [PubMed]
                OBJECTIVE: Acceptance of pain and values-based action appear important in the emotional, physical, and social functioning of individuals with chronic pain. The purpose of the current study was to prospectively investigate these combined processes. METHOD: 115 patients attending an assessment and treatment course for chronic pain in the U.K. completed a standard set of measures on two occasions separated by an average of 18.5 weeks. RESULTS: Correlation analyses showed that acceptance of pain and values-based action measured at Time 1 were significantly correlated with pain, pain-related distress, pain-related anxiety and avoidance, depression, depression-related interference with functioning, and physical and psychosocial disability measured at Time 2. Multiple regression analyses, in which pain and relevant patient background variables were controlled, showed that the combined acceptance and values measures accounted for between 6.5% and 27.0% of variance in six key measures of patient functioning later in time. CONCLUSION: These results support the importance of acceptance and values-related processes in relation to chronic pain. These results also encourage continued applications of a functional contextual model of psychopathology, the model underlying Acceptance and Commitment Therapy and related approaches such as Contextual Cognitive-Behavioral Therapy.

Vowles, K. E. and L. M. McCracken (2008). "Acceptance and values-based action in chronic pain: a study of treatment effectiveness and process." J Consult Clin Psychol 76(3): 397-407.   [PubMed]
                Developing approaches within cognitive behavioral therapy are increasingly process-oriented and based on a functional and contextual framework that differs from the focus of earlier work. The present study investigated the effectiveness of acceptance and commitment therapy (S. C. Hayes, K. Strosahl, & K. G. Wilson, 1999) in the treatment of chronic pain and also examined 2 processes from this model, acceptance and values-based action. Participants included 171 completers of an interdisciplinary treatment program, 66.7% of whom completed a 3-month follow-up assessment as well. Results indicated significant improvements for pain, depression, pain-related anxiety, disability, medical visits, work status, and physical performance. Effect size statistics were uniformly medium or larger. According to reliable change analyses, 75.4% of patients demonstrated improvement in at least one key domain. Both acceptance of pain and values-based action improved, and increases in these processes were associated with improvements in the primary outcome domains.

Zautra, A. J., M. C. Davis, et al. (2008). "Comparison of cognitive behavioral and mindfulness meditation interventions on adaptation to rheumatoid arthritis for patients with and without history of recurrent depression." J Consult Clin Psychol 76(3): 408-21.   [PubMed]
                This research examined whether cognitive behavioral therapy and mindfulness interventions that target responses to chronic stress, pain, and depression reduce pain and improve the quality of everyday life for adults with rheumatoid arthritis (RA). The 144 RA participants were clustered into groups of 6-10 participants and randomly assigned to 1 of 3 treatments: cognitive behavioral therapy for pain (P); mindfulness meditation and emotion regulation therapy (M); or education-only group (E), which served as an attention placebo control. The authors took a multimethod approach, employing daily diaries and laboratory assessment of pain and mitogen-stimulated levels of interleukin-6 (IL-6), a proinflammatory cytokine. Participants receiving P showed the greatest Pre to Post improvement in self-reported pain control and reductions in the IL-6; both P and M groups showed more improvement in coping efficacy than did the E group. The relative value of the treatments varied as a function of depression history. RA patients with recurrent depression benefited most from M across several measures, including negative and positive affect and physicians' ratings of joint tenderness, indicating that the emotion regulation aspects of that treatment were most beneficial to those with chronic depressive features.