title: What is the role of "nonorganic somatic components" in functional capacity evaluations in patients with chronic nonspecific low back pain undergoing fitness for work evaluation?
abstract: METHODS
  Analytical cross-sectional study.
  
  
  OBJECTIVE
  To assess the association of "nonorganic somatic components" together with physical and other psychosocial factors on functional capacity evaluation (FCE) in patients with chronic nonspecific low back pain (NSLBP) undergoing fitness-for-work evaluation.
  
  
  BACKGROUND
  Functional capacity evaluation is increasingly used for physical fitness-for-work evaluation in patients with chronic NSLBP, but results seem to be influenced by physical as well as psychosocial factors. The influence of nonorganic somatic components together with physical and other psychosocial factors on FCE performance has not yet been investigated.
  
  
  METHODS
  One hundred twenty-six patients with chronic NSLBP referred for physical fitness-for-work evaluation were included. The 4 FCE tests were lifting from floor to waist, forward bend standing, grip strength, and 6-minute walking. Nonorganic somatic components were assessed with the 8 nonorganic somatic signs as defined by Waddell and were adjusted for age, sex, days off work, salary in the previous occupation, pain intensity, fear avoidance belief, and perceived functional ability in multivariate regression analyses.
  
  
  RESULTS
  Between 42% and 58% of the variation in the FCE tests was explained in the final multivariate regression models. Nonorganic somatic components were consistent independent predictors for all tests. Their influence was most important on forward bend standing and walking distance, and less on grip strength and lifting performance. The physical factors of age and/or sex were strongly associated with grip strength and lifting, less with walking distance, and not at all with forward bend standing. The influence of at least 1 other psychosocial factor was observed in all FCE tests, having the highest proportion in the 6-minute walking test.
  
  
  CONCLUSIONS
  Nonorganic somatic components seem to be consistent independent predictors in FCE testing and should be considered for interpretation of test results.
authors.affiliation: Research Department, Rehabilitation Centre Valens, Switzerland. p.oesch@klinik-valens.ch
authors.forename: Peter
authors.initials: P
authors.lastname: Oesch
authors.forename: Kathrin
authors.initials: K
authors.lastname: Meyer
authors.forename: Beatrice
authors.initials: B
authors.lastname: Jansen
authors.forename: Petter
authors.initials: P
authors.lastname: Mowinckel
authors.forename: Stefan
authors.initials: S
authors.lastname: Bachmann
authors.forename: Kare Birger
authors.initials: KB
authors.lastname: Hagen
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D004651:Employment; D005080:Exercise Test; D005239:Fear / Q000523:psychology; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D008297:Male; D009784:Occupational Diseases / Q000175:diagnosis* / Q000503:physiopathology; D010147:Pain Measurement; D011590:Psychology, Industrial; D011594:Psychometrics; D020127:Recovery of Function; D012649:Self Concept; D012720:Severity of Illness Index; D014938:Work Capacity Evaluation; D014942:Workers' Compensation