DO ANTIDEPRESSANTS HAVE AN ANALGESIC EFFECT IN PSYCHOGENIC PAIN AND SOMATOFORM PAIN DISORDER - A METAANALYSIS

Objective: A significant amount of evidence indicates that some antide pressants have an analgesic effect. We wished to determine whether thi s analgesic effect could be demonstrated in studies that had used anti depressants for the treatment of pain in patients diagnosed with psych ogenic pain or somatoform pain disorder. Meta-analysis was used for th is purpose. Methods: All randomized, placebo-controlled antidepressant treatment studies of patients diagnosed with psychogenic pain disorde r or somatoform pain disorder were isolated. These studies were review ed and relevant statistics were coded. For each study, a single p valu e for the drug/placebo comparison was found or calculated for pain cha nge scores from pretreatment to completion of treatment. The z scores and effect sizes were calculated for each study, followed by a calcula tion of an overall z score and effect size. Results: Eleven studies fu lfilled the inclusion and exclusion criteria for this meta-analysis. T he combined difference showed that antidepressants decreased pain inte nsity in patients with psychogenic pain or somatoform pain disorder si gnificantly more than placebo (z = 5.71, p <.0001). The overall effect size was large (mean = 0.48) and ranged from 0 to 0.91. Conclusions: The results indicate that, in patients diagnosed with psychogenic pain or somatoform pain disorder, antidepressant treatment resulted in a r eduction in pain that was significantly greater than that of placebo. Possible explanations for these results are discussed.