title: The psychometric characteristics of an assessment instrument for perceived harmfulness in adolescents with musculoskeletal pain (PHODA-youth).
abstract: BACKGROUND
  Cognitive-behavioural models of chronic pain predict that dysfunctional assumptions about harmfulness of activities may maintain pain-related fear and disability. To assess perceived harmfulness in adolescents, the Photograph Series of Daily Activities for youth (PHODA-youth) was developed. Information concerning its methodological quality is currently lacking.
  
  
  OBJECTIVE
  To investigate psychometric characteristics (factor structure, test-retest reliability, construct validity) and feasibility of the PHODA-youth in adolescents with chronic musculoskeletal pain.
  
  
  METHODS
  Test-retest design.
  
  
  METHODS
  Adolescents aged 13-21 years with chronic nonspecific musculoskeletal pain.
  
  
  METHODS
  Participants filled in an electronic version of the PHODA-youth including 89 items twice with a 4-week interval. The instrument's factor structure was determined by a factor analysis. Construct validity was studied with criterion variables: catastrophizing (Pain Catastrophizing Scale for Children), pain intensity (visual analogue scale), depression (Children's Depression Inventory) and pain-related disability (Functional Disability Inventory) using regression analysis. Test-retest reliability was evaluated based on the Pearson correlation coefficient. Feasibility was studied with self-constructed questions.
  
  
  RESULTS
  Seventy-one adolescents participated. Results show a three-factor structure for the PHODA-youth including 51 items with subscales labelled as: 'activities of daily life', 'intensive physical activities' and 'social activities'. Total and subscale scores showed a high internal consistency. Its test-retest reliability was good (r = 0.94) and its construct validity is supported by the finding that both catastrophizing (β = 0.25; p = 0.02) and disability (β = 0.71; p < 0.001) were uniquely related to the PHODA-youth. In addition, feasibility appeared adequate.
  
  
  CONCLUSIONS
  The findings support the PHODA-youth as a valid and reliable measure of the perceived harmfulness of activities in adolescents with musculoskeletal pain.
authors.affiliation: Department of Rehabilitation Medicine, Research School CAPHRI, Maastricht University, The Netherlands; Adelante Centre of Expertise in Rehabilitation and Audiology, Hoensbroek, The Netherlands.
authors.forename: J A
authors.initials: JA
authors.lastname: Verbunt
authors.forename: A
authors.initials: A
authors.lastname: Nijhuis
authors.forename: M
authors.initials: M
authors.lastname: Vikström
authors.forename: A
authors.initials: A
authors.lastname: Stevens
authors.forename: N
authors.initials: N
authors.lastname: Haga
authors.forename: J
authors.initials: J
authors.lastname: de Jong
authors.forename: M
authors.initials: M
authors.lastname: Goossens
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D058443:Catastrophization / Q000523:psychology; D059350:Chronic Pain / Q000523:psychology; D003863:Depression / Q000175:diagnosis / Q000523:psychology; D004185:Disability Evaluation; D005163:Factor Analysis, Statistical; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D059352:Musculoskeletal Pain / Q000175:diagnosis* / Q000523:psychology*; D010147:Pain Measurement; D011594:Psychometrics / Q000379:methods*; D015203:Reproducibility of Results; D012919:Social Behavior; D055815:Young Adult