Responsiveness and minimal clinically important difference of the Persian versions of disability questionnaires in people with lumbar disc herniation

Abstract

Background and Objectives: Disability questionnaires are routinely measured in clinical practices and clinical researchs.The Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RMDQ), and Quebec Back Pain Disability Scale (QBPDS) are most widely used questionnaires that assess disability in patients with low back pain (LBP). Responsiveness is an important psychometric property of an instrument and assesses longitudinal changes in health status in treatment efficacy trials. The objective of this study is to examine and compare the responsiveness and minimal clinically important difference (MCID) of the Persian version of the ODI, RMDQ, and QBPDS in subjects with lumbar herniated disc submitted to a physical therapy program. Materials and Methods: Ninety two subjects with lumbar herniated disc and lumbar and lower limb pain completed the Persian version of the ODI, RMDQ, and QBPDS before and after the program. All patients also completed a global perception of change (GPE) Likert scale in condition after the program. This scale was collapsed to produce a dichotomous variable outcome: improved and non-improved. Responsiveness was determined using Receiver Operating Characteristic curve (ROC curve), with best cut-point analysis. The best change score cut-off was identified when equally balanced sensitivity and specificity was found, as an expression of the minimum clinically important difference (MCID). Results: ROC analysis revealed an area under the curve of 0.78 for the ODI and 0.70 for the QBPDS. The best cut-off point for ODI and QBPDS was 13 (70% sensitivity, 73% specificity) and 14/5 (60% sensitivity, 69% specificity). The area under the curve and the best cut-off point for RMDQ was 0.66 and 5/5 (40% sensitivity, 86% specificity). Conclusion:. The Persian version of Oswestry Disability Index and Quebec Back Pain Disability Questionnaire seems preferable to the Roland-Morris Disability Questionnaire for use in clinical trials and clinical practice among patients with herniated lumbar discs.