Background and objectives: In clinical examinations of a patient with non-specific low back pain (LBP), there is a need to dispose over a valid and quick to perform rating system. The "Backache Disability Index" for LBP or BADIX includes rating of 5 trunk movements in erect position and a "Morning Back Stiffness" score, whereof the sum gives the BADIX (max. 20 points). The objective of this study was to explore the reliability, responsiveness and concurrent validity of the BADIX. Patients with LBP (n=100) were randomly assigned into a "control" group (n=40) in function of validity studies, and a "treatment" group (n=60) in function of responsiveness studies. The treatment group underwent two weekly sessions of in total 30 minutes of deep cross-friction on the thoraco-lumbar Erector spinae and gluteals. All patients completed the Oswestry Disability Questionnaire validated Dutch version (ODQ), the McGill Pain Questionnaire (MPQ). The impairment examination consists, besides current orthopaedic and neurologic examinations, of the new BADIX scoring system.
Results: In our study the retest reliability after 3 days of the BADIX was perfect (n=039, r=0.95). A good correlation (p < 0.001) was found between BADIX at baseline, and Oswestry Disability Index (ODI) (n=93, r=0.76), and McGill-Quality of Life Index (r=0.74). Similar discriminative ability and effect size of measures was found for BADIX and ODI (n=54). It is proposed that the minimal detectable change should be equal or more than 2 points.
Conclusions: The "Backache Disability Index" appears to be a reliable and a valid assessment tool of morning stiffness and restricted spinal movements, and discriminates between successful and unsuccessful treatment outcome. The BADIX will allow patients to take snapshots of their daily treatment evolution, save them on their computer or tablets (apps) and share the results with their doctors and/or therapists.
Keywords: Low back pain; disability index; impairment; reliability; validity.