Catastrophizing, state anxiety, anger, and depressive symptoms do not correlate with disability when variations of trait anxiety are taken into account. a study of chronic low back pain patients treated in Spanish pain units [NCT00360802].

OBJECTIVES To assess the influence of pain severity, catastrophizing, anger, anxiety, and depression on nonspecific low back pain (LBP)-related disability in Spanish patients with chronic LBP. Study Design.  Cross-sectional correlation between psychological variables and disability. Methods.  One hundred twenty-three patients treated for chronic LBP in pain units within nine Spanish National Health Service Hospitals, in eight cities, were included in this study. Intensity of LBP and pain referred to the leg, disability, catastrophizing, anger, state anxiety, trait anxiety, and depression were assessed through previously validated questionnaires. The association of disability with these variables, as well as gender, age, academic level, work status, and use of antidepressants, was analyzed through linear regression models. RESULTS Correlations between LBP, referred pain, disability, catastrophizing, anger, state anxiety, trait anxiety, and depression were significant, except for the ones between anger and LBP and between anger and referred pain. The multivariate regression model showed that when variations of trait anxiety were taken into account, the association of the other psychological variables with disability was no longer significant. The final model explained 49% of the variability of disability. Standardized coefficients were 0.452 for trait anxiety, 0.362 for intensity of LBP, 0.253 for failed back surgery, and -0.140 for higher academic level. CONCLUSION Among Spanish chronic LBP patients treated at pain units, the correlation of catastrophizing, state anxiety, anger, and depression with disability ceases to be significant when variations of trait anxiety are taken into account. Further studies with LBP patients should determine whether anxiety trait mediates the effects of the other variables, explore its prognostic value, and assess the therapeutic effect of reducing it.