Invited Commentary

Walsh and hall and Schafer et al have published two papers on the sub-classification of back-related leg pain, according to patho-anatomical sources of those symptoms. The papers demonstrated some of the necessary features of a clinically useful classification system. For instance, reasonably clear-cut operational definitions and the use of an algorithmic clinical reasoning process to determine classification. One paper demonstrated that the four sub-groups differed from each other in terms of Oswestry scores and in terms of fear-avoidance beliefs about physical activity, but not in other measures that they used (Walsh & hall). The importance of this is not made clear, but appears to be seen as relevant to choice of interventions. The other study demonstrated moderate inter-rater reliability of the system, with kappa values of 0.72 (Schafer et al).

The only point of a classification system is if it optimises treatment outcomes for the identified sub-groups. Walsh and hall help to describe sub-groups, but do not identify how treatment might be optimised. however, this is clearly work in progress and the development of optimal treatments for the different sub-groups is undoubtedly part of the research program.

The authors stated that it is not their intention to replace existing classification systems, but simply to add to them, with the suggestion that their system can be used in conjunction with existing systems, with a particular emphasis on the sub-classification of neural related disorders. It is not clear how this would work— a patient with back and leg pain could already be classified and treated according to a number of classification systems. The intent of a classification system is to direct management; multiple classification systems would suggest multiple choices of treatment, and thus a complicated life for clinicians. The intent of a classification system however should be to facilitate clinical reasoning.

Numerous classification systems for low back pain already exist, at the last count it was well over 30. McKenzie¹ first suggested that musculoskeletal problems were best managed with the use of nonspecific classifications that linked examination findings to treatment; and the development and exploration of classification systems has become a major goal for research groups. however the plethora of systems makes it difficult for clinicians to decide what is the most useful way to classify their patients. Ideally classification systems should be speaking the same language, but the burgeoning number of systems with different classifications and interventions has become an additional source of confusion rather than a help to clinicians and patients. To progress forward, it would be helpful to determine the most common and important elements in these classification systems.