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Depressive subtype did not affect antidepressant treatment outcomes

Results from a multiple-phase, multisite, open-label, randomized practical clinical trial suggest that depressive subtypes may play an insignificant role in antidepressant selection.

“Major depressive disorder is a heterogeneous condition in which a wide range of etiologies, risk factors and symptom profiles may be associated with a threshold diagnosis. Response to treatment is highly variable,” study researcher Bruce A. Arnow, PhD, of Stanford University School of Medicine, and colleagues wrote. “Not only does treatment outcome vary substantially among depressed patients who are treated in a similar fashion, but there is little evidence that one treatment is superior to another, whether comparing antidepressant medications, among psychotherapies, or between the two.”

To assess overlaps among depressive subtypes and the association between subtypes and responsiveness to commonly used antidepressants, researchers conducted the International Study to Predict Optimized Treatment in Depression (iSPOT-D) among 1,008 patients aged 18 to 65 years across 17 sites in five countries. Study participants met DSM-5 criteria for diagnosis of current single-episode or recurrent nonpsychotic major depressive disorder. They were randomized to receive escitalopram, sertraline or extended-release venlafaxine for 8 weeks.

Seventy-five percent of patients met criteria for at least one of the three depressive subtypes, and of these, 52% met criteria for a single subtype and 48% met criteria for more than one subtype. Thirty-six percent of patients met criteria for two or more depressive subtypes and 11% met criteria for all three subtypes.

Logistic regression indicated no differences in remission rates among subtype groups. Patients who received escitalopram, sertraline and venlafaxine had comparable odds of achieving remission.

There was no statistically significant interaction between subtype and treatment, suggesting that subtype was not a moderator of treatment effect.

“This exploratory study revealed substantial overlap among anxious, atypical and melancholic depression subtypes, a finding consistent with [previous] observations. Whether pure or mixed, subtypes were not differentially predictive of overall acute treatment outcomes or differentially predictive of efficacy among the three antidepressant medications. If replicated, these findings would suggest that the clinical utility of these subtypes in treatment selection is minimal,” Arnow and colleagues concluded. – by Amanda Oldt

Disclosure: Arnow reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.