Four comparative studies (RCTs) randomised 788 participants. In addition the recommendations of the American psychiatric Association (APA) and the Agency for Health Care Policy and Research were evaluated in the discussion.
In the first study, differences were non significant between lithium and amitryptyline, but statistically significant between drug and placebo (p = 0.025). Observed relapse rates were quite high.
In the second study, the investigators concluded that IMI and lithium were better than placebo in the long-term treatment of MDD.
In the third study, the authors concluded that IMI was better than lithium in patients with severe illness, and that a combination regimen offered no advantages. In the fourth study, Kaplan-Meier curves showed IMI with or without IPT-M to be the best maintenance treatment consistently over the 3 years of follow-up, followed by IPT-M with or without placebo, and then placebo.
The APA guidelines note that various antidepressants and lithium have been shown to be effective and IMI at the usual acute therapeutic dose has been documented effective for up to 5 years. The full acute dose may not be necessary but should be used if it does not cause undue side effects. Maintenance electroshock therapy (generally about one treatment per month) is also noted to be appropriate for some patients.
The AHCPR guidelines favour medication for maintenance treatment and generally sees psychotherapy as adjunctive. It is recommended that individuals with a lifetime history of three episodes be maintained on a full therapeutic dose of an antidepressant for a period of 1 to several years after the most recent episode.