title: Rasch analysis supported the construct validity of self-report measures of activity and participation derived from patient ratings of the ICF low back pain core set.
abstract: OBJECTIVE
  To investigate whether measures of activity limitations and participation restrictions with sound internal construct validity could be derived from patient ratings of the International Classification of Functioning, Disability and Health Low Back Pain Core Set (LBP-CS).
  
  
  METHODS
  The LBP-CS Self-Report Checklist (LBP-CS-SRC) was developed to permit patients to self-rate their functioning according to an extended set of activity and participation categories from the LBP-CS. Rasch analysis was used to examine the validity of the LBP-CS-SRC with a sample of 308 adults with chronic low back pain attending two tertiary-referral outpatient services in Brisbane, Australia.
  
  
  RESULTS
  The activity limitations and participation restrictions qualifier scales functioned satisfactorily, and the LBP-CS-SRC person response validity was good. After deletion of six misfitting items, the dimensionality results supported using the instrument as distinct measures of activity limitations (17 items) and participation restrictions (10 items). The activity and participation measures both had good person separation reliability, and no component items exhibited meaningful differential item functioning.
  
  
  CONCLUSIONS
  The results demonstrate that measures of activity and participation with sound internal construct validity can be derived from patient ratings of LBP-CS categories. The LBP-CS-SRC can be used in clinical practice and epidemiologic research to support understanding of patients' perspectives on functioning.
authors.affiliation: Interdisciplinary Persistent Pain Centre, Gold Coast Hospital and Health Service, 2 Investigator Drive, Robina, Queensland 4226, Australia; Occupational Therapy Department and the Orthopaedic Physiotherapy Screening Clinic, Royal Brisbane and Women's Hospital, Butterfield St, Herston, Queensland 4029, Australia; Occupational Therapy, School of Health and Rehabilitation Sciences, The University of Queensland, Chancellors Place, St Lucia, Brisbane, Queensland 4072, Australia. Electronic address: Karl.Bagraith@gmail.com.
authors.forename: Karl S
authors.initials: KS
authors.lastname: Bagraith
authors.affiliation: Occupational Therapy, School of Health and Rehabilitation Sciences, The University of Queensland, Chancellors Place, St Lucia, Brisbane, Queensland 4072, Australia.
authors.forename: Jenny
authors.initials: J
authors.lastname: Strong
authors.affiliation: Occupational Therapy, School of Health and Rehabilitation Sciences, The University of Queensland, Chancellors Place, St Lucia, Brisbane, Queensland 4072, Australia.
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Meredith
authors.affiliation: Centre for Functioning and Health Research, Metro South Hospital and Health Service, Cnr of Ipswich Road and Cornwall Street, Buranda, Queensland 4102, Australia; Institute of Health and Biomedical Innovation and School of Public Health & Social Work, Queensland University of Technology, Victoria Park Road, Kelvin Grove, Queensland 4059, Australia.
authors.forename: Steven M
authors.initials: SM
authors.lastname: McPhail
mesh_terms: D000203:Activities of Daily Living; D001315:Australia; D057189:Checklist / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D057566:Self Report / Q000592:standards*
keywords: Activity; International Classification of Functioning, Disability and Health; Low back pain; Participation; Rasch analysis; Validity