Chronic pain in children and adolescents is common; approximately 5% of children and adolescents report chronic pain along with moderate to high pain-related disability. Chronic pain is a subjective experience and can best be explained by a bio-psycho-social approach, which suggests reciprocal relations between different levels of this multidimensional phenomenon. The different dimensions of chronic pain need to be considered for a comprehensive assessment. Due to the subjective nature of pain, the child’s self-report is usually considered the best available and most valid estimate of the pain experience. A reliable and multidimensional assessment is an indispensable requirement for treatment planning. To date, questionnaires in German language are available to assess a wide range of relevant parameters in pediatric chronic pain. However, so far, no validated self-report tool exists to assess sensory and affective pain perception in children. These two parameters are of relevance since they describe aspects of the biological as well as the psychological dimension of chronic pain. Furthermore, a comprehensive diagnostic approach combining parameters from the three dimensions of chronic pain does not yet exist for children and adolescents. Such a comprehensive approach could be used for sample descriptions and standardized comparisons across different populations; it could serve as an approach for treatment planning or to classify outcome. This doctoral thesis is aimed at further developing the available diagnostic measures for older children and adolescents with chronic pain based on the above mentioned gaps in pediatric pain assessment. Research was performed on three patient samples. Sample 1 includes data from a prospective assessment at the German Pediatric Pain Centre from August 2008 to March 2009 (N(1)=139). Sample 2 includes retrospective data from patients who were treated at the German Pediatric Pain Centre from July 2005 to June 2010 (N(2)=1242). Sample 3 consists of pediatric pain patients who started an intensive interdisciplinary inpatient treatment between November 2009 and July 2011 (N(3)=83). In a first study, a tool to assess sensory and affective pain perception, the Pain Perception Scale for Adolescents, was adapted and validated in an adolescent clinical sample (Sample 1). The Pain Perception Scale for Adolescents allows pain patients to provide a valid and reliable self-report of parameters for both the biological and psychological dimensions of pain. In a second study, this tool was applied to a further sample of adolescents with migraine and tension-type headache (subsample of Sample 2). It was demonstrated that, contrary to the official headache classification guidelines, the sensory pain perception in this sample did not differentiate between migraine and tension-type headache. To develop a multidimensional assessment approach, in a third study, an adult classification system (Chronic Pain Grading) was applied to a sample of pediatric pain patients (Sample 2). This approach proved useful as a valid measure for a brief operationalization of pain problem severity, including pain intensity and pain-related disability only, and as an outcome measure. However, it displayed major shortcomings with regards to treatment stratification. To further develop an approach for treatment stratification and treatment planning, a fourth study focused on developing a new multidimensional approach for subgroup classification (subsample of Sample 2). The stability of subgroups was demonstrated in a cross-validation with an independent sample (Sample 1). Furthermore, the identified subgroups displayed distinct treatment outcomes after a standardized treatment program (Sample 3). In conclusion, this doctoral thesis offers an addition to diagnostic measures for older children and adolescents with chronic pain by adding the Pain Perception Scale for Adolescents and by proving the validity of the Chronic Pain Grading for the application in this patient group. These tools allow a valid description of adolescents’ subjective pain experience. Results from this doctoral thesis also indicate that the findings from adults cannot be readily transferred to children and adolescents. The final output of this doctoral thesis is a bio-psycho-social classification approach that identifies subgroups of adolescents with chronic pain with treatment relevant differences. This is a first step toward the development of subgroup-specific treatment.

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