Abstract
A literature search identified eight classification systems that subdivide non-specific low back pain. These eight systems were selected on the basis of the following criteria: they were all developed for the purpose of guiding choice of physiotherapeutic treatments, and they were all based on symptoms and clinical tests. A critical appraisal was performed using a systematic approach including evaluation of validity, reliability, feasibility, and generalizability. None of the classification systems fulfilled all of the requirements and none were considered to have included all relevant categories separated in a way suitable for the purpose. Studies concerning reliability and validity were rarely reported. Generally aspects of validity and reliability were only tested for a few of the criteria used for categorizing patients and construct validity and reliability of the classification systems as a whole were not tested. Future studies ought to focus on the evaluation of existing classification systems and/or the development of new ones, which are capable of meeting basic measurement criteria.