title: Disability, pain, psychological factors and physical performance in healthy controls, patients with sub-acute and chronic low back pain: a case-control study.
abstract: OBJECTIVE
  To compare measures of disability, psychological factors, pain and physical performance in healthy controls, and patients with sub-acute and chronic low back pain. To evaluate the concept of the deconditioning syndrome and to explore factors that may contribute to chronicity.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Three age- and gender-matched groups were included in the study; healthy controls (n = 45), patients sick-listed 8-12 weeks (n = 46) and patients with chronic low back pain on a waiting list for lumbar instrumented fusion (n = 45).
  
  
  METHODS
  Measures of disability, pain, psychological factors, and physical performance were obtained from the 3 groups using validated measures.
  
  
  RESULTS
  Gender, age, body weight and height were not significantly different between the groups. Comparable scores were found for self-rated working ability, fear-avoidance beliefs for physical activity and aerobic capacity in the 2 patient groups. Oswestry Disability Index, pain, emotional distress, abdominal and back muscle endurance were significantly different between the 3 groups. Self-efficacy for pain and fear-avoidance beliefs for work was significantly different between the 2 patient groups.
  
  
  CONCLUSIONS
  The results suggest a stepwise deterioration of impairment and disability from healthy controls to patients with chronic low back pain. Most variables distinguished between healthy controls and patients with sub-acute or chronic low back pain. Deconditioning was more related to psychophysical measures of abdominal and back muscle endurance than to cardiovascular fitness. Comparable scores for fear-avoidance and working ability in the 2 patient categories suggest that these factors appear at an early stage and contribute to the transition from acute to chronic low back pain.
authors.affiliation: Department of Orthopaedic Surgery, Section for Back Surgery and Physical Medicine and Rehabilitation, National Hospital, Oslo, Norway. jens.ivar.brox@rikshospitalet.no
authors.forename: Jens Ivar
authors.initials: JI
authors.lastname: Brox
authors.forename: Kjersti
authors.initials: K
authors.lastname: Storheim
authors.forename: Inger
authors.initials: I
authors.lastname: Holm
authors.forename: Astrid
authors.initials: A
authors.lastname: Friis
authors.forename: Olav
authors.initials: O
authors.lastname: Reikerås
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002908:Chronic Disease; D004185:Disability Evaluation; D005239:Fear; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology; D008875:Middle Aged; D020377:Self Efficacy; D018582:Sick Leave; D014938:Work Capacity Evaluation