The Inter-Tester Reliability of Physical Therapists Classifying Low Back Pain Problems Based on the Movement System Impairment Classification System

ObjectiveThe classification of patients with low back pain (LBP) may be important for improving clinical outcomes and research efficiency. The purpose of this study was to examine the inter-tester reliability of 2 trained physical therapists to classify patients with LBP by using the standardized Movement System Impairment (MSI) classification system. The 5 proposed MSI classifications are based on the most consistent patterns of movement and alignment observed throughout the examination that correlate with the patient's symptom behavior.DesignTest-retest to assess reliabilitySettingAcademic healthcare center outpatient facilityParticipantsThirty subjects (21 women and 9 men) with chronic, recurrent LBP (mean age 31.1 ± 12.9 years) were examined independently by 2 experienced physical therapists.MethodsTraining consisted of self-study of a procedure manual, a supervised practice of examination procedures and classification rules, and discussion. Subjects were examined independently by each therapist using a test-retest design. Each therapist assigned a LBP classification upon completion of the examination. Both therapists were blinded to the other therapist's findings.Main Outcome MeasuresInter-tester reliability of therapists classifying the LBP problems was indexed by the percent agreement and kappa coefficient.ResultsOverall percent agreement on the classification assigned was 83% with kappa = 0.75 (95% confidence interval = 0.51-0.99; P < .0001).ConclusionInter-tester reliability of classification of patients with LBP when therapists use a standardized clinical examination based on the MSI classification system is substantial.