The predictive validity of atypical neurovegetative depressive symptoms identified by the first principal component in the DUAG trial of moclobemide versus clomipramine

Abstract

To investigate to what extent the primary depression subtype atypical depression can predict differential outcome of the mono-amino-oxidase inhibitor (MAO-I) moclobemide and the tricyclic antidepressant clomipramine in the Danish University Antidepressant Group Study (DUAG). In a randomised, double blind trial, a total of 117 patients with major depression were treated over 6 weeks with either 400 mg moclobemide or 150 mg clomipramine. A baseline principal component analysis (PCA) was performed to identify atypical symptoms on the combined depression scales (Hamilton Depression Scale (HAM-D(17)) and the Quantitative Scale for Atypical Depression (QSAD)). The primary outcome scale was the subscale HAM-D(6) which contains the pure items of depression. PCA identified two items with loadings opposite to the other depression items within HAM-D(17) and QSAD, namely increased duration of sleep and increased appetite (atypical neurovegetative symptoms). Patients with a positive score at baseline on these items were classified as having atypical depression. In total 13 patients were classified as having atypical depression. Within this group of patients 8 received clomipramine and 5 patients received moclobemide. At endpoint the moclobemide treated patients had a significantly better response than the clomipramine treated (P=0.036), effect size 1.42, when using HAM-D(6) as outcome. However, in the 104 patients classified as having typical depression clomipramine was superior to moclobemide (P=0.034), effect size 0.47. The number of patients with atypical neurovegetative symptoms was very small and no placebo arm was included. It is very important to screen for atypical depression (increased duration of sleep/increased appetite) in the acute therapy of patients with major depression. Our results add to the body of evidence that monoamine oxidase inhibitors are superior to tricyclic antidepressants in this sub-group of patients.