IntroductionMajor depressive disorder (MDD) is a highly prevalent mental disorder that is associated with significant levels of disability, morbidity, and mortality. It is one of the leading causes of disability globally, affecting nearly 350 million people worldwide,1 and the burden associated with MDD continues to increase.2 The 2010 Global Burden of Disease Study, for instance, showed a 37% increase in disability-adjusted life years due to MDD between 1990 and 2010.2 MDD is also known to have a major impact on health-related quality of life (QoL) and functioning. For example, a previous study by Rapaport et al3 reported that approximately 63% of patients with MDD and 85% of patients with chronic/double depression (ie, an MDD episode on top of dysthymia) entering clinical trials had severe QoL impairments.