Should anxiety and insomnia influence antidepressant selection: a randomized comparison of fluoxetine and imipramine

The more sedating antidepressants are often recommended for patients presenting with anxiety or insomnia. We examine whether baseline anxiety or insomnia symptoms (1) show differential response to fluoxetine or imipramine or (2) predict differences between drugs in overall clinical response or likelihood of medication discontinuation.

336 health maintenance organization primary care patients beginning antidepressant treatment for depression were randomly assigned to an initial prescription for fluoxetine or imipramine. All subsequent care (medication dosage, change, or discontinuation) was managed as usual by the primary care physician. The 17-item Hamilton Rating Scale for Depression (HAM-D) and the Hopkins Symptom Checklist (SCL) anxiety and depression subscales were administered prior to randomization and 1 month later.

Rates of improvement in insomnia (HAM-D insomnia items), agitation (HAM-D agitation item), and anxiety (SCL anxiety subscale) were essentially identical in the two treatment groups. Baseline level of insomnia did not predict significant differences between randomization groups in improvement in overall HAM-D score (p = .44) or SCL depression subscale (p = .44). Similarly, baseline level of anxiety did not predict significant differences in improvement in HAM-D (p = .19) or SCL depression subscale (p = .31). Patients assigned to fluoxetine were significantly less likely to change or discontinue antidepressant medication during the first month, but this difference did not vary according to baseline level of insomnia (p = .68) or anxiety (p = .25).

Among patients with moderate depression, baseline levels of insomnia or anxiety should not influence the choice of fluoxetine or imipramine as an initial antidepressant.