Influence of comorbidity with depression on interdisciplinary therapy: outcomes in patients with chronic low back pain

INTRODUCTION: Our previous work showed higher tumour necrosis factor (TNF)-α levels in patients with chronic low back pain (cLBP) compared to healthy controls. However, patients with depression as a comorbidity did not have higher TNF-α levels in comparison to patients without depression. In this study we investigated the influence of depression on therapy outcomes such as TNF-α serum levels, pain intensity and back function in patients with cLBP. Our hypothesis was that patients with both cLBP and depression benefit no less than patients with cLBP alone from the multidisciplinary pain therapy. METHODS: A total of 58 patients with cLBP alone or with both cLBP and depression were age- and sex-matched with 29 healthy controls. Serum concentrations of TNF-α were assayed at the beginning of the study (T0) and 10 days (T1), 21 days (T2), and 180 days (T3) later. The clinical outcomes such as pain intensity, as well as back function, sleep, exercise, alcohol and nicotine consumption were documented. In the first three weeks, all patients underwent multidisciplinary therapy based upon biological, psychological, physical and psychosocial components. RESULTS: Over the whole course there were no differences in TNF-α level between cLBP patients with and without depression. At T0, both cLBP patients with (cLBP+DE) and without (cLBP) depression showed significantly higher TNF-α serum levels (P = 0.002 for cLBP+DE, P = 0.004 for cLBP) than healthy controls (HC) that normalized after 10 days of therapy and remained similar to healthy controls. During the follow-up, the depression scales were normalised and pain intensity was significantly reduced. Both evidences processed parallel to the reduction of TNF-α levels, which correlates neither with depression score nor with pain intensity at any time point. CONCLUSIONS: Depression as a comorbidity to chronic low back pain did not influence the serum TNF-α level in the course of six months, but seemed to affect the success of therapy. cLBP patients with comorbidity of depression benefit from multidisciplinary pain therapy not only to the same extent but also to a greater degree than cLBP patients without depression.