J Manipulative Physiol Ther. 1995 Feb; 18(2): 79-87.
Low back pain outcome measurement assessment in chiropractic teaching clinics: responsiveness and applicability of two functional disability questionnaires.
Research Department, Western States Chiropractic College, Portland, OR 97230-3099, USA.
OBJECTIVE: The major aims were to evaluate responsiveness and clinical/research applicability of the Revised Oswestry Disability Questionnaire (ODQ) and the Dallas Pain Questionnaire (DPQ). Construct and content validity were assessed. Patient characteristics and outcomes were also documented. DESIGN: Longitudinal observational study. SETTING: College outpatient clinics. PARTICIPANTS: Six hundred sixty-three consecutive new patients accepted for treatment of low back pain (LBP) at the clinics over a 1-yr period, age 18 or older. INTERVENTIONS: Treatment of low back pain by senior interns under the supervision of staff clinicians. MAIN OUTCOME MEASURES: ODQ and DPQ administered at baseline, 2 wk, 1 month, and monthly up to 6 months. Responsiveness: mean standardized change score (delta' = mudif/sigma dif), relative efficiency ([RE = delta' ODQ/delta DPQ']2), and improvement rates (IR). Applicability: instrument completion rates. Construct validity: correlation with VAS for pain intensity. RESULTS: ODQ responsiveness was generally consistent over time (delta' = .70-.83) and negligibly better than the DPQ activities of daily living scale (RE = 1.00-1.35); most patients self-reporting improvement showed positive outcomes (IR = 97%). For large samples (n > 100): delta' = .47-.63 and IR = 81% for the DPQ work/leisure scale; delta' = .17-.40 and IR = 54% for the DPQ anxiety/depression and social dimensions. Completion rates: 65%-78% of all instruments; 81%-100% of individual scales. Construct validity: r = .44-.68 for the ODQ, DPQ activities of daily living, and DPQ work/leisure scales; r = .20-.40 for the anxiety/depression scale. CONCLUSIONS: The ODQ and the activities of daily living and work/leisure scales from the DPQ appear appropriate for monitoring LBP patients returning for care to chiropractic teaching clinics. The social and anxiety/depression dimensions of the DPQ do not appear to be responsive in this population. The latter scale may be unsuitable on the grounds of misinterpretations.