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McKenzie Lumbar Classification: Inter-rater Agreement by Physical Therapists With Different Levels of Formal McKenzie Postgraduate Training

Werneke, Mark W., PT, MS, Dip. MDT*; Deutscher, Daniel, PT, PhD; Hart, Dennis L., PT, PhD†,‡; Stratford, Paul, PT, MSc§; Ladin, Joel, PT; Weinberg, Jon, PT, Dip. MDT; Herbowy, Scott, PT, Dip. MDT**; Resnik, Linda, PT, PhD‡‡

doi: 10.1097/BRS.0000000000000117
Health Services Research

Study Design. Inter-rater chance-corrected agreement study.

Objective. The aim was to examine the association between therapists' level of formal precredential McKenzie postgraduate training and agreement on the following McKenzie classification variables for patients with low back pain: main McKenzie syndromes, presence of lateral shift, derangement reducibility, directional preference, and centralization.

Summary of Background Data. Minimal level of McKenzie postgraduate training needed to achieve acceptable agreement of McKenzie classification system is unknown.

Methods. Raters (N = 47) completed multiple sets of 2 independent successive examinations at 3 different stages of McKenzie postgraduate training (levels parts A and B, part C, and part D). Agreement was assessed with κ coefficients and associated 95% confidence intervals. A minimum κ threshold of 0.60 was used as a predetermined criterion for level of agreement acceptable for clinical use.

Results. Raters examined 1662 patients (mean age = 51 ± 15; range, 18–91; females, 57%). Data distributions were not even and were highly skewed for all classification variables. No training level studied had acceptable agreement for any McKenzie classification variable. Agreements for all levels of McKenzie postgraduate training were higher than expected by chance for most of the classification variables except parts A and B training level for judging lateral shift and centralization and part D training level for judging reducibility. Agreement between training levels parts A and B, part C, and part D were similar with overlapping 95% confidence intervals.

Conclusion. Results indicate that level of inter-rater chance-corrected agreement of McKenzie classification system was not acceptable for therapists at any level of formal McKenzie postgraduate training. This finding raises concerns about the clinical utility of the McKenzie classification system at these training levels. Additional studies are needed to assess agreement levels for therapists who receive additional training or experience at the McKenzie credentialed or diploma levels.

Level of Evidence: 2

Results indicate inadequate agreement for judging McKenzie main syndromes, presence of lateral shift, derangement, reducibility, directional preference, and centralization by physical therapist raters completing formal McKenzie training levels parts A and B, C, and D. Future research is warranted to examine the implementation and educational processes required to obtain adequate agreement.

*CentraState Medical Center, Freehold, NJ

Physical Therapy Service, Maccabi Healthcare Services, Tel Aviv, Israel

Focus On Therapeutic Outcomes, Inc., White Stone, VA

§School of Rehabilitation Science, Institute of Applied Sciences and Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada

Physical Therapy Service, Maccabi Healthcare Services, Tel Aviv, Israel

Team Care Physical Therapy, Oxford, NC

**Physical Therapy Department, St David's Hospital Austin, TX; and

††Providence VA Medical Center, Providence, RI, and Department of Health Services, Policy and Practice, Brown University, Providence, RI.

Address correspondence and reprint requests to Mark W. Werneke, PT, MS, Dip. MDT, CentraState Medical Center, 901 West Main St, Freehold, NJ 07728; E-mail:

Acknowledgment date: June 24, 2013. First revision date: September 10, 2013. Second revision date: October 12, 2013. Acceptance date: October 21, 2013.

†Died April 11, 2012.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work.

There were no relevant financial activities outside the submitted work: board membership, consultancy, employment, payment for lecture.

© 2014 by Lippincott Williams & Wilkins