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Open Access Research article

Influence of depression symptoms on serum tumor necrosis factor-α of patients with chronic low back pain

Haili Wang1*, Carsten Ahrens1, Winfried Rief2, Simone Gantz1, Marcus Schiltenwolf1 and Wiltrud Richter1

Author Affiliations

1 Department of Orthopaedic Surgery, University of Heidelberg, Schlierbacher Landstrasse 200a, 69118 Heidelberg, Germany

2 Department of Clinical Psychology and Psychotherapy, University of Marburg, Gutenbergstrasse 18, 35032 Marburg, Germany

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Arthritis Research & Therapy 2010, 12:R186  doi:10.1186/ar3156

Published: 11 October 2010

Abstract

Introduction

Patients with chronic low back pain (cLBP) have high rates of comorbid psychiatric disorders, mainly depression. Recent evidence suggests that depressive symptoms and pain, as interacting factors, have an effect on the circulating levels of inflammatory markers relevant to coronary artery disease. Our previous work showed a higher serum level of an inflammatory marker tumour necrosis factor-alpha (TNFα) in patients with cLBP, which did not correlate with intensity of low back pain alone. In the present study we investigated the cross-sectional associations of depressive symptoms, low back pain and their interaction with circulating levels of TNFα.

Methods

Each group of 29 patients with cLBP alone or with both cLBP and depression was age-matched and sex-matched with 29 healthy controls. All subjects underwent a blood draw for the assessment of serum TNFα and completed a standardised questionnaire regarding medication, depression scores according to the German version of Centre for Epidemiological Studies Depression Scale (CES-D), pain intensity from a visual analogue scale, and back function using the Roland and Morris questionnaire. The correlations between TNFα level and these clinical parameters were analysed.

Results

There were no differences in TNFα level between cLBP patients with and without depression. Both cLBP patients with (median = 2.51 pg/ml, P = 0.002) and without (median = 2.58 pg/ml, P = 0.004) depression showed significantly higher TNFα serum levels than healthy controls (median = 0 pg/ml). The pain intensity reported by both patient groups was similar, while the patients with depression had higher CES-D scores (P < 0.001) and worse back function (P < 0.001). The variance analysis showed that the interaction between TNFα level and pain intensity, CES-D scores, sex, body mass index and medication was statistically significant.

Conclusions

Depression as a comorbidity to cLBP did not influence the serum TNFα level. It seems that TNFα somehow acts as a mediator in both cLBP and depression, involving similar mechanisms that will be interesting to follow in further studies.