University of Groningen Relationship between psychological factors and performance-based and self-reported disability in chronic low back pain

Cross sectional study, performed in an outpatient university based pain rehabilitation setting. To analyze the relationship between psychological factors (psychosocial distress, depression, self efficacy, selfesteem, fear of movement, pain cognitions and coping reactions) and performance-based and self-reported disability, as measured with a Functional Capacity Evaluation (FCE) and the Roland Morris Disability Questionnaire (RMDQ), in patients with chronic low back pain (CLBP). It has been suggested that a strong relationship exists between psychological factors and disability in patients with CLBP. In former research disability was often measured by self-report and seldom performance-based. Study sample consisted of 92 patients with CLBP admitted for multidisciplinary rehabilitation. Prior to treatment, all patients completed questionnaires to measure psychological factors and self-reported disability, and performed an FCE to measure performance-based disability. Correlation coefficients between psychological variables and FCE and self-reported disability were calculated. Multivariate linear regression analyses were performed with self-reported or performance based disability measures as outcome variables, and psychological measures as predictor variables. Out of 42 relations analyzed, 5 were statistically significant. This concerned one significant correlation between kinesiophobia and a subtest of FCE, and four correlations between psychological factors and RMDQ. No correlation was significant after the Bonferroni correction was applied (P \ 0.001). The strength of significant correlations ranged from r = -0.33 to r = 0.25. The multivariate analysis revealed that psychological variables measured in this study could explain 19% of the variance of self-reported disability, with kinesiophobia being the only psychological variable that contributed significantly. The suggested strong relationship between psychological factors and performance-based and selfreported disability could not be confirmed in this study. This may implicate that the relationship between psychological factors and disability in patients with CLBP is not as unambiguous as suggested. H. R. Schiphorst Preuper (&) M. F. Reneman P. U. Dijkstra J. H. B. Geertzen S. Brouwer Center for Rehabilitation, University Medical Center Groningen, University of Groningen, PO Box 30.002, 9750 RE Haren, Groningen, The Netherlands e-mail: h.r. schiphorst.preuper@cvr.umcg. nl H. R. Schiphorst Preuper M. F. Reneman P. U. Dijkstra J. H. B. Geertzen S. Brouwer Graduate School for Health Research SHARE, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands A. M. Boonstra Center for Rehabilitation, ‘Revalidatie Friesland’, Beetsterzwaag, The Netherlands P. U. Dijkstra Department of Oral and Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands G. J. Versteegen Pain Expertise Center, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands S. Brouwer Department of Health Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands 123 Eur Spine J (2008) 17:1448–1456 DOI 10.1007/s00586-008-0772-0