Venlafaxine versus Mirtazapine in the??Treatment of Undifferentiated Somatoform Disorder

Abstract

We set out to compare the efficacy and tolerability of mirtazapine versus venlafaxine in patients with undifferentiated somatoform disorder (USD) using the Patient Health Questionnaire-15 (PHQ-15). This was a 12-week prospective, open-label, randomized, parallel-group trial. The trial consisted of six visits that included baseline and weeks 1, 2, 4, 8 and 12. The primary effectiveness measure was the mean change in PHQ-15 total score from baseline to the end of treatment. Secondary effectiveness measures included the mean changes in total scores on the Beck Depression Inventory (BDI) and the 12-item General Health Questionnaire (GHQ) from baseline to the end of treatment. Ninety-five subjects were randomized to either mirtazapine (n = 50) or venlafaxine (n = 45); 71 subjects completed the study (mirtazapine: n = 39/50 [78%]; venlafaxine: n = 32/45 [71%]). The mean total score on the PHQ-15 decreased by 34.7% (-8.4, p < 0.0001) from baseline to endpoint in the mirtazapine group and by 26.6% (-6.1, p < 0.0001) in the venlafaxine group. A marginally significant between-group difference was observed for the mean change in total score on the PHQ-15 from baseline to endpoint (F = 4.126, p = 0.046). The mean total scores on the GHQ-12 and BDI from baseline to endpoint decreased by -4.9 (29.4%, p < 0.0001) and -13.5 (55.9%, p < 0.0001), respectively, in the mirtazapine group, and by -4.3 (26.2%, p = 0.001) and -9.02 (46.0%, p < 0.0001), respectively, in the venlafaxine group. No between-group difference was observed for the mean changes in total scores on the secondary effectiveness measures from baseline to endpoint. Both treatments were well tolerated. Our findings suggest that both mirtazapine and venlafaxine may be effective and well tolerated in the treatment of patients with USD. Double-blind, placebo-controlled and/or head-to-head comparison studies are required to allow definite conclusions to be drawn.