title: Measuring illness beliefs in patients with lower extremity injuries: reliability and validity of the Dutch version of the Somatic Pre-Occupation and Coping questionnaire (SPOC-NL).
abstract: BACKGROUND
  Positive coping strategies, illness perceptions and recovery expectations are associated with better clinical outcomes and earlier return to work after injuries. The Somatic Pre-Occupation and Coping (SPOC) questionnaire captures illness beliefs and coping towards recovery of physical function and return to work after surgical treatment of tibial shaft fractures. The aim of this study was to translate and culturally adapt the SPOC into Dutch (SPOC-NL) and evaluate its reliability and validity in patients with lower extremity injuries.
  
  
  METHODS
  The SPOC-NL contains four subscales: Somatic complaints, Coping, Energy, and Optimism. Patients treated for lower extremity injuries (N=106) completed the SPOC-NL, Short Form-36 and Short Musculoskeletal Function Assessment (SMFA-NL) questionnaire, and reported their current work status and self-perceived work ability. To assess test-retest reliability, 56 patients completed the SPOC-NL for a second time two weeks after the first administration of the SPOC-NL. We calculated Cronbach's Alpha, intraclass correlation coefficients (ICCs) and G coefficients to measure internal consistency and overall reliability, and used the Bland and Altman method to assess bias between test and retest SPOC-NL scores. To determine construct validity, we explored 16 a priori hypotheses regarding correlations between SPOC-NL scores and subscale scores and SF-36, SMFA-NL, work status and work ability.
  
  
  RESULTS
  Internal consistency was good to excellent, with Cronbach's Alpha values ranging between 0.79 and 0.94 and G coefficients ranging between 0.77 and 0.95. Test-retest reliability was also good, since high ICCs (0.72-0.91) and G coefficients (0.82-0.94) were found. Construct validity of the SPOC-NL was good, as 75% of the predefined hypotheses were confirmed. Compared to participants who were on sick leave or receiving disability benefits, participants with a paid job had significantly higher scores on the total score and the subscales Somatic complaints and Energy of the SPOC-NL. Participants with high work ability also had significantly higher scores on the total score and all subscales than participants with low work ability.
  
  
  CONCLUSIONS
  The SPOC-NL is a reliable and valid measure for the assessment of illness beliefs and coping towards recovery and it is strongly related to work status and self-perceived ability to work in patients with lower extremity injuries.
authors.affiliation: Department of Trauma Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address: i.h.f.reininga@umcg.nl.
authors.forename: Inge H F
authors.initials: IH
authors.lastname: Reininga
authors.affiliation: Department of Health Sciences, Division of Community & Occupational Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Sandra
authors.initials: S
authors.lastname: Brouwer
authors.affiliation: Department of Trauma Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Anita
authors.initials: A
authors.lastname: Dijkstra
authors.affiliation: Department of Anesthesia, McMaster University, Hamilton, Ontario, Canada; Department of Biostatistics and Clinical Epidemiology, McMaster University, Hamilton, Ontario, Canada; The Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Busse
authors.affiliation: Department of Anesthesia, McMaster University, Hamilton, Ontario, Canada; Department of Biostatistics and Clinical Epidemiology, McMaster University, Hamilton, Ontario, Canada; Stanford Prevention Research Center, Department of Medicine, Stanford University, Stanford, USA; Department of Anaesthesia & Pain Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Shanil
authors.initials: S
authors.lastname: Ebrahim
authors.affiliation: Department of Trauma Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Wendt
authors.affiliation: Department of Trauma Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Mostafa
authors.initials: M
authors.lastname: El Moumni
mesh_terms: D000223:Adaptation, Psychological; D004185:Disability Evaluation; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007869:Leg Injuries / Q000503:physiopathology / Q000523:psychology* / Q000534:rehabilitation; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D010147:Pain Measurement / Q000379:methods*; D010361:Patients / Q000523:psychology* / Q000706:statistics & numerical data; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011594:Psychometrics; D011788:Quality of Life; D020127:Recovery of Function; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires
keywords: Clinimetric properties; Coping; Cross-cultural adaptation; Illness beliefs; Injury; Lower extremity; Recovery expectations; Return to work