A Process of Subgroup Identification in Non-specific Low Back Pain Using a Standard Clinical Examination and Cluster Analysis

Background and Purpose: Non-specific low back pain (NSLBP) accounts for over 85% of all low back pain. Homogenous subgroups may exist within this diagnosis. This study derived a clinical examination and evaluated the examination's ability to identify homogenous subgroups in NSLBP. Methods: Patients with NSLBP were examined using a standardized clinical examination. Each patient was examined by two physiotherapists. Data were analysed for item reliability and the presence of distinct subgroups using cluster analysis. Cross-validation of the clusters identified was conducted. Results: Three hundred and one patients were examined. The inter-tester reliability of the majority of items was moderate to substantial (52% of items with kappa>0.40). A K-means cluster analysis of the two data sets revealed agreement on the presence of two subgroups. One group (n=47, 16%) had higher fear avoidance beliefs, anxiety and disability. They were more likely to be provoked by pain provocative tests. They were also more likely to be judged as having central sensitization and a dominant psychosocial component to their presentation. Conclusion: The identification of a group of hypervigilant NSLBP patients should allow the interventions to be targeted towards this group. A valid, standardized clinical examination does contribute to the diagnostic management of NSLBP. © 2011 John Wiley & Sons, Ltd.