Intertester reliability of McKenzie's classifications of the syndrome types present in patients with low back pain

The McKenzie system for examining and treating patients with low back pain is frequently used by clinicians. The primary purpose of this multicenter study was to determine the intertester reliability of assessments of patients with low back pain when physical therapists used the McKenzie method. A second purpose was to determine if previous postgraduate training in the McKenzie system affects reliability. Some therapists had previously undertaken postgraduate training in the McKenzie system. All therapists were given written descriptions of the McKenzie method and the criteria used to classify patients. Classifications were made on 363 patients with low back pain by randomly paired physical therapists in eight clinics. The Kappa value on agreement of patient classification was 0.26, which suggests poor reliability. Therapists agreed on which syndrome was present 39% of the time. Previous postgraduate training did not improve reliability. The results suggest that assessments of the syndrome present in patients with low back pain appear to be unreliable when using the McKenzie system.