A randomized double-blind clinical trial on analgesic efficacy of fluoxetine for persistent somatoform pain disorder

Abstract

Objectives To verify the efficacy and safety of fluoxetine in treating patients with persistent somatoform pain disorder (PSPD). Methods In this 8-week, randomized double-blind placebo-controlled study, 80 patients with an ICD-10 diagnosis of PSPD were randomly assigned to receive 20 mg fluoxetine or a placebo. Several psychological scales including Medical Outcomes Study Pain Measures (MOSPM), Hamilton Depression Scale-17 items (HAMD 17) and Treatment Emergent Symptom Scale (TESS) were used to assess analgesic efficacy and safety of fluoxetine, and the possible analgesic mechanism of fluoxetine was preliminarily analyzed. All data were analyzed by SPSS11.5 with t-test, one-way ANOVA and a mixed-effects model repeated measures analysis. Intent-to-treat (ITT) analysis was performed and the last observation carry forward (LOCF) was used for missing values. Results There was a significant difference of MOSPM total score between the fluoxetine and placebo group after 2 weeks of treatment. The analgesic effect of fluoxetine was related with treatment time, and depressive patients showed a better analgesic effect than non-depressive patients. An adverse effect of fluoxetine was scarcely found. Conclusions Fluoxetine has a better analgesic effect than a placebo in treating persistent somatoform pain disorder, and is considered a safe treatment; its analgesic effect may be related to an antidepressant effect.