Interrater reliability of a new classification system for patients with neural low back-related leg pain

The aim of this study was to investigate the reliability of a new classification system for low back-related leg pain arising from neural tissue dysfunction. Leg pain is a frequent accompaniment to back pain and is an indicator of the severity and prognosis of the disorder. For optimal patient care, treatment should be directed according to the identified pathophysiological mechanisms. The authors have proposed a sub-classification of neural low back-related leg pain into four categories, each requiring a different management strategy: Central Sensitization (CS), comprising major features of sensitization of the somatosensory system; Denervation (D), arising from significant axonal compromise without evidence of major central nervous system changes; Peripheral Nerve Sensitization (PNS), arising from nerve trunk inflammation without clinical evidence of significant denervation; and Musculoskeletal pain (M), referred from non-neural structures such as the disc or facet joints. The purpose of this study was to investigate the interrater reliability of this classification system. Forty consecutive patients with unilateral low back-related leg pain were independently assessed by five pairs of examiners using a physical examination protocol, screening for central sensitization of the somatosensory system, neurological deficit, and nerve tissue mechano-sensitization. Subjects were classified as follows: CS 30%, D 27.5%, PNS 10%, and M 32.5%. Interrater reliability was good with 80% agreement and a k of 0.72 (95% Confidence Interval (CI) .57-.86). The findings of the study demonstrate that patients with low back-related leg pain can be reliably classified to one of the four proposed groups.