title: Treatment expectancy and credibility are associated with the outcome of both physical and cognitive-behavioral treatment in chronic low back pain.
abstract: BACKGROUND
  Patients' initial beliefs about the success of a given pain treatment are shown to affect final treatment outcome. The Credibility/Expectancy Questionnaire (CEQ) has recently been developed as measure of treatment credibility and expectancy.
  
  
  OBJECTIVE
  The objectives of this study were (1) to investigate the factor structure of the CEQ in a sample of chronic low back pain (CLBP) patients by means of a confirmatory factor analysis, (2) to examine the association between treatment credibility and expectancy and patient characteristics, and (3) to assess whether treatment expectancy and credibility are associated with the outcome of rehabilitation treatment.
  
  
  METHODS
  CLBP patients (n=167) were randomized to either active physical therapy (n=51), cognitive-behavioral therapy (n=57), or a combination therapy (n=59), and completed the CEQ after a careful explanation of the treatment rationale.
  
  
  RESULTS
  Confirmatory factor analysis supported the 2-factor structure (credibility/expectancy) of the CEQ. Lower credibility was associated with higher pain-related fear and lower internal control of pain, and lower expectancy with higher levels of pain-related fear and no radiating pain. Multiple linear regression analyses revealed that after controlling for age, sex, treatment center, pain-intensity at baseline, duration of disability, and irrespective of the treatment offered, expectancy was significantly associated with disability and satisfaction. Credibility was significantly associated with patient-specific symptoms and satisfaction. For global perceived effect, treatment expectancy was predictive in active physical therapy only, and treatment credibility was a significant predictor in combination therapy only.
  
  
  CONCLUSIONS
  Although the associations found were low to modest, these results underscore the importance of expectancy and credibility for the outcome of different active interventions for CLBP and might contribute to the development of more effective treatments.
authors.affiliation: Rehabilitation Centre Blixembosch, Eindhoven, The Netherlands. rsmeets@iae.nl
authors.forename: Rob J E M
authors.initials: RJ
authors.lastname: Smeets
authors.forename: Saskia
authors.initials: S
authors.lastname: Beelen
authors.forename: Mariëlle E J B
authors.initials: ME
authors.lastname: Goossens
authors.forename: Erik G W
authors.initials: EG
authors.lastname: Schouten
authors.forename: J André
authors.initials: JA
authors.lastname: Knottnerus
authors.forename: Johan W S
authors.initials: JW
authors.lastname: Vlaeyen
mesh_terms: D000223:Adaptation, Psychological; D000293:Adolescent; D000328:Adult; D000368:Aged; D002908:Chronic Disease; D015928:Cognitive Behavioral Therapy / Q000379:methods*; D003131:Combined Modality Therapy / Q000379:methods; D004185:Disability Evaluation; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000523:psychology* / Q000534:rehabilitation*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010349:Patient Compliance; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D016896:Treatment Outcome