title: The lack of association between changes in functional outcomes and work retention in a chronic disabling occupational spinal disorder population: implications for the minimum clinical important difference.
abstract: METHODS
  A prospective study in a chronic pain/ disability population, relating changes in the Oswestry Disability Index (ODI), as well as the Mental Component Summary (MCS) and Physical Component Summary (PCS) of the Short Form-36 (SF-36), to work retention (WR) status at 1-year postrehabilitation.
  
  
  OBJECTIVE
  To explore the relationship between WR status and change in ODI, and the MCS and PCS of the SF-36, and determine if an MCID can be identified using WR as an external criterion for the group of patients under consideration.
  
  
  BACKGROUND
  Clinically meaningful change may be defined through self-report, physician- based, or objective criteria of improvement, although most assessments have been based on self-report assessment of improvement. The disability occurring after work-related spinal disorders lends itself to anchoring self-report measures to objective work status outcomes 1-year post-treatment. Additional research is needed to evaluate the relationship between change and objective markers of improvement.
  
  
  METHODS
  A consecutive cohort of patients (n = 2024) with chronic disabling occupational spinal disorders completed an interdisciplinary functional restoration program, and underwent a structured clinical interview for objective, socioeconomic outcomes at 1-year post-treatment. The average percent change in the ODI, as well as the MCS and PCS of the SF-36, were calculated for patients who successfully retained work and those who had not after completing a functional restoration program. Predictive ability of the percent change scores were evaluated through logistic regression analysis.
  
  
  RESULTS
  No percent difference variables were strong predictors of WR status 1-year following treatment.
  
  
  CONCLUSIONS
  The current analyses suggest that the ODI and SF-36 MCS and PCS measures are not responsive at the individual patient level when WR data are used as the external criterion using an anchor-based approach. This finding contrasts to reports of responsiveness based on distributional methods, or methods using self-report anchors of change.
authors.affiliation: PRIDE Research Foundation, Dallas, TX, USA. hdwilson@u.washington.edu
authors.forename: Hilary D
authors.initials: HD
authors.lastname: Wilson
authors.forename: Tom G
authors.initials: TG
authors.lastname: Mayer
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Gatchel
mesh_terms: D000328:Adult; D002908:Chronic Disease; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000628:therapy*; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000706:statistics & numerical data; D011446:Prospective Studies; D012044:Regression Analysis; D012647:Self-Assessment; D013122:Spinal Diseases / Q000628:therapy*; D011795:Surveys and Questionnaires; D014937:Work