5. Inadequate response to antidepressants: having a score of ≥14 on the 17-item HAMD or a CGI-S score of ≥ 3 after a retrospective confirmation of an adequate trial of a single antidepressant (defined as an 6-week trial of acceptable therapeutic dose [40 mg of fluoxetine, paroxetine 30 mg of citalopram, 20 mg of escitalopram, 37.5 mg of paroxetine CR, 150 mg of sertraline, 100 mg of fluvoxamine, 225 mg of venlafaxine XR)