Centralization: association between repeated end-range pain responses and behavioral signs in patients with acute non-specific low back pain.

OBJECTIVE Tests and measures, if confounded by behavioral signs, cloud interpretation of physical test results during clinical examination. The purpose of this study was to determine whether common behavioral signs and pain responses (i.e. centralization and non-centralization) were associated during initial examination. DESIGN Observational and designed to cross-tabulate pain responses to behavioral signs. PATIENTS Data from 177 consecutive patients with acute work-related low back syndromes referred to physical therapy were analysed. METHODS Patients were screened for 8 baseline behavioral signs. Pain responses during initial evaluation were determined from repeated end-range trunk movement tests or loading strategies following McKenzie assessment methods. Association between centralization and non-centralization and baseline behavioral signs were assessed. RESULTS The physical sign of non-centralization was associated with non-organic signs, overt pain behaviors, fear of work activities, and somatization. Although depression, fear of physical activities, disability and pain intensity were not associated with non-centralization (p>0.05), upper bounds of odds ratios confidence intervals suggest that these behavioral signs may not be entirely independent of pain responses. CONCLUSION Presence of non-centralization is associated with many behavioral signs, and therefore when present, clinicians should consider additional psychosocial screening during the initial evaluation.