A Cochrane review [Abstract] 1 included 10 studies with a total of 722 subjects. Seven trials were of high quality. Nine trials included patients with chronic low-back pain and one trial did not specify the duration of the low-back pain of the included patients. All studies included low-back pain patients with a mix of clinical diagnoses, such as radicular symptoms, herniated disc or spondylolisthesis. Only one study explicitly selected patients with low-back pain and significant depressive symptoms. Four studies included a mix of patients who were depressed and patients who were not depressed, three trials excluded patients with major depression, and in two studies it was unclear if patients were depressed or not. Most studies evaluated the effectiveness of tricyclic antidepressants. Three studies evaluated a selective serotonin reuptake inhibitor (paroxetine, fluoxetine) and two studies investigated 'atypical' antidepressants, bupropion (aminoketone antidepressant) and trazodone. The pooled analyses showed no difference in pain relief (six trials; SMD -0.04 95% CI -0.25 to 0.17), functional status (two trials; SMD -0.06 95% CI -0.40 to 0.29) or depression (two trials; SMD 0.06 95% CI -0.29 to 0.40) between antidepressant and placebo treatments. There was no difference in pain relief between tricyclic antidepressants and placebo (SMD -0.10 95% CI -0.51 to 0.31) or SSRI:s versus placebo (SMD 0.11 95% CI -0.17 to 0.39). The qualitative analyses found conflicting evidence on the effect of antidepressants on pain intensity in chronic low-back pain, and no clear evidence that antidepressants reduce depression in chronic low-back pain patients.
Comment: The quality of evidence is downgraded by inconsistency (variability in results across studies) and by by imprecise results (limited study size for each comparison).
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