title: Clinical classes of injured workers with chronic low back pain: a latent class analysis with relationship to working status.
abstract: To determine (a) clinical classes of injured workers with chronic low back pain (CLBP), (b) predictors of class membership and (c) associations of classes with baseline work status.
  
  
  
  Patients with CLBP from a tertiary care outpatient clinic in Toronto, Canada were sampled. Latent class analysis was applied to determine class structure using physical, psychological and coping indicators. Classes were interpreted by class-specific means and analyzed for predictors of membership. Lastly, association of the classes with being off work was modeled.
  
  
  
  A 3-class model was chosen based on fit criteria, theoretical and clinical knowledge of this population. The resultant 3 classes represented low, moderate and high levels of clinical severity. Predictors of being in the high severity group compared to the low severity group were < high school education [odds ratio (OR) 3.06, 95% CI (1.47, 6.37)] and comorbidity total [OR 1.28, 95% CI (1.03, 1.59)]. High severity class membership was associated with four times increased risk of being off work at baseline compared to those in the low severity group [OR 3.98, 95% CI (1.61, 6.34)].
  
  
  
  In a cohort of injured workers with CLBP, 3 clinical classes were identified with distinct psychological and physical profiles. These profiles are useful in aiding clinicians to identify patients of high clinical severity who may be potentially at risk for problematic return to work.
authors.affiliation: School of Rehabilitation, Faculty of Medicine, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC, H3C 3J7, Canada. lisa.carlesso@umontreal.ca.|Hôpital Maisonneuve-Rosemont Research Centre, Montréal, Canada. lisa.carlesso@umontreal.ca.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Carlesso
authors.affiliation: Division of Orthopedic Surgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Raja Rampersaud
authors.affiliation: Health Care and Outcomes Research, Toronto Western Research Institute, University Health Network, Toronto, Canada.|Department of Physical Therapy and Institute of Rehabilitation Science and Institute of Health, Policy, Management and Evaluation, University of Toronto, Toronto, Canada.
authors.forename: Aileen M
authors.initials: AM
authors.lastname: Davis
mesh_terms: D000328:Adult; D002170:Canada; D059350:Chronic Pain / Q000175:diagnosis* / Q000523:psychology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D004651:Employment / Q000523:psychology / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis* / Q000523:psychology; D008297:Male; D008875:Middle Aged; D060051:Occupational Injuries / Q000175:diagnosis* / Q000523:psychology; D010147:Pain Measurement / Q000379:methods; D000071066:Patient Reported Outcome Measures; D011594:Psychometrics / Q000379:methods*
keywords: Clinical classes; Latent variable mixture model; Low back injury; Workers