title: Intercorrelation and test-retest reliability of the Pain Disability Index (PDI) and the Oswestry Disability Questionnaire (ODQ) and their correlation with pain intensity in low back pain patients.
abstract: OBJECTIVE
  To determine the intercorrelation between subjective disability, as assessed with the Pain Disability Index (PDI) and the Oswestry Disability Questionnaire (ODQ) and their correlation with visual analogue scale (VAS) pain intensity ratings.
  
  
  METHODS
  Questionnaires were administered to 94 patients with chronic low back pain with or without radiation into the legs of at least 3 months' duration.
  
  
  METHODS
  Tertiary care center.
  
  
  RESULTS
  High correlations were noted between the ODQ and PDI (r = 0.83) and PDI factor 1 (r = 0.84), a subscale of the PDI. Lower correlations were noted between pain intensity (VAS) scores and the ODQ (r = 0.62) and the PDI (r = 0.69). A weaker correlation (r = 0.41) was noted between the ODQ and PDI factor 2. Intraclass correlation coefficients (ICC) for test-retest reliability in 20 patients (time interval 1 week) were for the ODQ ICC = 0.83, PDI ICC = 0.91, PDI percentage score ICC = 0.91, PDI factor 1 ICC = 0.87, and PDI factor 2 ICC = 0.73, respectively.
  
  
  CONCLUSIONS
  The present results suggest that either the PDI or the percentage score PDI and also the even shorter-to-administer PDI factor 1 may be useful and reliable tests for the assessment of subjective disability in low back pain patients. As noted by the moderate intercorrelations with pain intensity scores, both the PDI and the ODQ address a broader concept of disability than that directly related to pain intensity.
authors.affiliation: Spine Research Unit, Helsinki University Central Hospital, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Grönblad
authors.forename: M
authors.initials: M
authors.lastname: Hupli
authors.forename: P
authors.initials: P
authors.lastname: Wennerstrand
authors.forename: E
authors.initials: E
authors.lastname: Järvinen
authors.forename: A
authors.initials: A
authors.lastname: Lukinmaa
authors.forename: J P
authors.initials: JP
authors.lastname: Kouri
authors.forename: E O
authors.initials: EO
authors.lastname: Karaharju
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis* / Q000523:psychology; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000295:instrumentation*; D011795:Surveys and Questionnaires