title: Psychometric evaluation of a new instrument to measure uncertainty in children and adolescents with cancer.
abstract: BACKGROUND
  Although uncertainty has been characterized as a major stressor for children and adolescents with cancer, it has not been studied systematically.
  
  
  OBJECTIVE
  The objective of this study was to describe the development and initial psychometric evaluation of a measure of uncertainty in school-aged children and adolescents with cancer.
  
  
  METHODS
  Interview data from the first author's qualitative study of uncertainty in children undergoing cancer treatment (Stewart, 2003) were used to generate 22 items for the Uncertainty Scale for Kids (USK), which were evaluated for content validity by expert panels of children with cancer and experienced clinicians (Stewart, Lynn, & Mishel, 2005). Reliability and validity were evaluated in a sample of 72 children aged 8 to 17 years undergoing cancer treatment.
  
  
  RESULTS
  The USK items underwent minor revision following input from content validity experts, and all 22 were retained for testing. The USK demonstrated strong reliability (Cronbach's alpha = .94, test-retest r = .64, p = .005), and preliminary evidence for validity was supported by significant associations between USK scores and cancer knowledge, complexity of treatment, and anxiety and depression. Exploratory factor analysis yielded two factors, not knowing how serious the illness is and not knowing what will happen when, which explained 50.4% of the variance.
  
  
  CONCLUSIONS
  The USK, developed from the perspective of children, performed well in the initial application, demonstrating strong reliability and preliminary evidence for construct and discriminant validity. It holds considerable promise for moving the research forward on uncertainty in childhood cancer.
authors.affiliation: School of Nursing, University of Pittsburgh, Pittsburgh, PA 15261, USA. stewj@pitt.edu
authors.forename: Janet L
authors.initials: JL
authors.lastname: Stewart
authors.forename: Mary R
authors.initials: MR
authors.lastname: Lynn
authors.forename: Merle H
authors.initials: MH
authors.lastname: Mishel
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D001007:Anxiety / Q000209:etiology / Q000523:psychology*; D002648:Child; D002652:Child Behavior / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000150:complications / Q000523:psychology* / Q000628:therapy; D011594:Psychometrics; D011788:Quality of Life / Q000523:psychology; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012944:Social Support; D011795:Surveys and Questionnaires; D017741:Survivors / Q000523:psychology; D035501:Uncertainty