Incidence of treatment-resistant depression during the first mood depressive episode.

Introduction: In spite of several approaches and therapeutic measures, treatment-resistant depression (TRD) continues to inflict serious, individual and collective consequences. Therefore, there is a persistent need to scrutinize the concept of TRD in order to adapt the therapeutic strategies.

Aim: To estimate the incidence of TRD in patients with a first major depressive episode (MDD), and study factors associated with resistance.