title: Factor analyses for the Örebro Musculoskeletal Pain Questionnaire for working and nonworking patients with chronic low back pain.
abstract: The Örebro Musculoskeletal Pain Questionnaire (ÖMPQ) has good psychometric properties to predict return to work in patients with acute low back pain. Although it is used in patients with chronic back pain and nonworkers, there is no evidence on the factor structure of the ÖMPQ in these populations. This is deemed an important prerequisite for future prediction studies.
  
  
  
  This study aimed to analyze the factor structure of the ÖMPQ in working and nonworking patients with chronic back pain.
  
  
  
  This is a cross-sectional study in a university-based spine center.
  
  
  
  The patient sample consists two cohorts of working and nonworking adult patients (>18 years) with specific and nonspecific chronic back pain.
  
  
  
  The Örebro Musculoskeletal Pain Questionnaire.
  
  
  
  Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were performed in working (N=557) and nonworking (N=266) patients for three, four, five, and six factors identified in literature. A goodness of fit index was calculated by a chi-square. Root mean square error of approximation (RMSEA) was calculated, and the number of factors identified was based on RMSEA values <.05. A Tucker-Lewis index (TLI) and a normed fit index (NFI) >0.90 are considered to indicate acceptable fit.
  
  
  
  In working patients, a five-factor solution had the best fit (RMSEA<0.05; NFI and TLI >0.90), but substantial adaptations should be made to get proper fit (removal of the work-related items). In nonworking patients, a four-factor analysis had the best fit (RMSEA<0.05). For both samples, items related to duration could not fit in the overall model.
  
  
  
  Factor structure of the ÖMPQ was not confirmed in working and nonworking patients with chronic back pain. Substantial adaptations should be made to obtain a factor structure with acceptable fit.
authors.affiliation: Groningen Spine Center, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands; Saxion Universities of Applied Sciences, M.H. Tromplaan 28, PO Box 70.000, 7500 KB, Enschede, The Netherlands. Electronic address: r.soer@umcg.nl.
authors.forename: Remko
authors.initials: R
authors.lastname: Soer
authors.affiliation: Department of Neurology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands.
authors.forename: Patrick
authors.initials: P
authors.lastname: Vroomen
authors.affiliation: Department of Public Health, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands.
authors.forename: Roy
authors.initials: R
authors.lastname: Stewart
authors.affiliation: Groningen Spine Center, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands; Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Coppes
authors.affiliation: Groningen Spine Center, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands.
authors.forename: Patrick
authors.initials: P
authors.lastname: Stegeman
authors.affiliation: Department of Rehabilitation Medicine, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands; Department of Oral and Maxilofacial Surgery, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: Dijkstra
authors.affiliation: Department of Rehabilitation Medicine, University Medical Center Groningen, University of Groningen, Hanzeplein 1, PO Box 30001, 9750 RB Groningen, The Netherlands.
authors.forename: Michiel
authors.initials: M
authors.lastname: Reneman
mesh_terms: D000328:Adult; D004651:Employment; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D008297:Male; D008875:Middle Aged; D059352:Musculoskeletal Pain / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*
keywords: Confirmatory factor analyses; Disability; Musculoskeletal pain; Psychometric properties; Psychosocial factors; Spinal pain