The reliability of the McKenzie classification system using extremity McKenzie assessment forms

Objectives: To investigate the reliability of experienced physiotherapists in classifying patients in McKenzie’s non-specific mechanical syndromes from extremity McKenzie assessment forms. Design: Inter-therapists reliability pilot study using patient vignettes. Setting: NHS outpatients department, UK. Method: Three McKenzie ‘credentialed’ therapists, who had taken a course in Mechanical Diagnosis and Therapy for the Extremities, independently examined 11 completed McKenzie assessment forms with the classification conclusion omitted. These had been completed by a fourth therapist who was a faculty member of the McKenzie Institute teaching programme, and whose classification conclusions represented a ‘gold standard’ against which to judge the other therapists’ conclusions. Outcomes: Reliability was expressed as percentage agreement and kappa. Results: The reliability of syndrome classification was ‘good’, 82% agreement, kappa 0.7. Against the ‘gold standard’ the therapist with more training was more reliable. Conclusion: In this pilot study, the reliability of McKenzie’s mechanical syndrome classification in extremity patients was good and warrants further investigation in a larger cohort of therapists and amongst real patients rather than paper vignettes.