More than pain : assessment and treatment of pain-related dysfunction in pediatric chronic pain

Background: Pediatric chronic pain is prevalent, affecting between 11-38% of children and adolescents, with a subset of individuals suffering from substantial pain-related disability. Dysfunction in emotional, social and physical domains, as well as parental distress, commonly co-occurs with pediatric chronic pain. The effectiveness of behavior oriented treatments for child pain intensity and disability is today well known, but there is still a need for further development of such treatments, including evaluations of different treatment formats and parent support programs. There is also a need to further develop and evaluate instruments to assess pain-related dysfunction in pediatric chronic pain. Purpose and aims: The purpose of this doctoral project was to develop effective ways to assess and treat dysfunction in pediatric chronic pain. The aims were to 1) evaluate the psychometric properties of the Insomnia Severity Index (ISI) for youths (study I) and the psychometric properties of the Pain Interference Index (PII) (study II), 2) investigate the prevalence of insomnia and the relationships between sleep and functioning (emotional and physical) (study I), 3) identify and evaluate existing research on intensive interdisciplinary treatment (IIPT) for pediatric chronic pain (study III), 4) investigate the effects of Acceptance and Commitment Therapy (ACT) on functioning in a clinical pilot study of individual and group treatment for adolescents with chronic pain (study IV) and 5) investigate the effects of parental support based on ACT on functioning in a clinical pilot study of individual and group treatment for parents of adolescents with chronic pain (study IV). Methods: Psychometric properties of the ISI and the PII were evaluated using cross-sectional data from pediatric participants with chronic debilitating pain. Evaluations included principal component analysis, correlational and regression analyses, and analysis of internal consistency. The importance of insomnia for the relationships between pain intensity, depression and functional disability were assessed by examining the indirect effects of insomnia in the relationship between pain and depression, and between pain and functional disability. To evaluate the current evidence for IIPT for pediatric chronic pain, a systematic review and meta-analysis was conducted. Finally, to investigate the effects of individual and group ACT treatment for adolescents with chronic pain and their parents, non-parametric analyses of differences between groups and over time were conducted, as well as analyses of clinically significant changes for adolescent and parent outcomes. Results: Results from the psychometric evaluations in study I and II supported the concurrent criteria validity and reliability for the ISI and the PII in this sample. The principal component analysis supported a 1-factor solution for PII. More than half of the sample reported clinically relevant scores of insomnia, and indirect effects of insomnia were found for the relationships between pain and depression, and between pain and functional disability. In study III, the systematic searches resulted in 10 studies matching criteria for inclusion (1 randomized controlled trial and 9 non randomized studies), and the meta-analysis yielded preliminary evidence for positive treatment effects of IIPT, but findings showed substantial heterogeneity. In study IV, adolescents reported significant improvements in functioning outcomes (i.e. pain interference, pain reactivity, depression, and psychological flexibility). Parents reported improvements in parental pain reactivity and psychological flexibility. There were no differences between group and individual treatment, and the pattern of results illustrated significant changes during the second half of treatment. Clinically significant changes were reported to a large extent in adolescent (21-63%) and parent (54-76%) variables. Conclusions and further directions: The PII and ISI are reliable and valid instruments that can be used to assess pain interference and insomnia in children and adolescents presenting with chronic pain. IIPT holds promise as a treatment format for addressing pain and painrelated dysfunction, but due to a small number of studies and methodological weaknesses, more research in this field is needed. The treatment evaluation of ACT for adolescents with chronic pain supported the promising findings from previous studies, illustrating improvements in adolescent functioning after treatment. Also, results indicate the utility of the ACT based parent support. Particularly, larger clinical trials with rigorous methodology are needed to evaluate the relative utility of individual and group treatment formats, mechanisms of change and the effects of parental support programs