Exposure and acceptance in patients with chronic debilitating pain : A behavior therapy model to improve functioning and quality of life

Sammanfattning: A large number of patients suffer from reduced functioning and quality of life due to longstanding pain. The importance of psychological factors is undisputable and there is today substantial empirical support for treatments based on cognitive behavior therapy (CBT). Nevertheless, previous research also illustrates a clear need for improvements. For example, there is a lack of studies with children and adolescents that are severely disabled by longstanding pain other than headache. Also, the process by which CBT is effective is still rather unclear. Recently, developments within CBT, such as Acceptance and Commitment Therapy (ACT), suggest an approach that, in contrast to reduction or control of symptoms, promotes acceptance of negative private experiences like chronic pain and distress. This type of intervention is aimed at improving functioning and quality of life by increasing psychological flexibility, i.e. the ability to act in alignment with personal values also in the presence of e.g. pain, fear, and negative thoughts. Although studies exist, there is an urgent need for randomized controlled trials with chronic pain patients, especially children and adolescents. The presented studies were conducted within the development of a clinical model to improve functioning and quality of life in children, adolescents, and adults with chronic debilitating pain. The thesis had two general aims. One, to investigate the effectiveness of an intervention based on values-oriented exposure and acceptance (studies 1, 2, and 4 in the present thesis). Two, to develop and psychometrically evaluate a self-report instrument designed to assess psychological flexibility in people with chronic pain (studies 2 and 5). Initially, an uncontrolled pilot study (study 1) was conducted with adolescents suffering from chronic idiopathic pain (n=16). Following treatment, large and stable reductions were seen in e.g. functional disability, pain intensity, and catastrophizing, with generally large effect sizes. Study 3 included people with chronic pain and whiplash associated disorders (WAD) (n=22). Exposure and acceptance delivered in addition to treatment as usual (TAU) was compared with a control group receiving only TAU. Following the exposure and acceptance intervention, improvements were seen in all measures but pain intensity, and these effects were retained seven months following the end of treatment. Furthermore, significant differences following treatment, in favor of the exposure and acceptance group, were seen in e.g. pain disability, life satisfaction, fear of movement, and psychological inflexibility, with moderate to large effect sizes. In study 4, participants were children and adolescents with chronic idiopathic pain (n=32). The effectiveness of exposure and acceptance was evaluated by comparing it with a multidisciplinary treatment approach including amitriptyline (MDT). The exposure and acceptance group showed large and sustained improvements in all measures, including functioning, quality of life, and pain intensity, with mostly large effects sizes. The exposure and acceptance group performed significantly better than the MDT on e.g. perceived functional ability in relation to pain, kinesiophobia, pain intensity and pain related discomfort, with moderate to large effect sizes. Parallel to the treatment evaluations, two studies were conducted to develop and evaluate an instrument to assess central and discernible components of psychological flexibility, referred to as the Psychological Inflexibility in Pain Scale (PIPS). In the development study (study 2), data was collected from pain clinics and patient organizations (n=203). Based on an original set of 38 items, principal component analyses suggested a two-factor solution with 16 items, showing adequate internal consistency and concurrent criterion validity. In study 5, participants were recruited from a patient organization for people with WAD (n=611). Exploratory and confirmatory factor analyses resulted in a two-factor solution with 12 items, illustrating good reliability and validity. Only items that were retained in both studies 2 and 5 were included in the final version of the instrument. Furthermore, hierarchical regression analyses illustrated that PIPS explained a significant amount of variance in e.g. pain, work absence, life satisfaction, disability, depression, and kinesiophobia. In conclusion, despite some methodological limitations, the treatment evaluations indicate the effectiveness of the exposure and acceptance intervention, and suggest that it may be superior to TAU only, as well as to a multidisciplinary program including amitriptyline. Furthermore, data from two measurement development studies suggest that PIPS can be used as a reliable and valid measure to assess key components in psychological inflexibility in people with chronic pain. More studies are needed to confirm these findings; especially larger scale randomized controlled trials.