The aim of iSPOT-D is to identify biological pretreatment measures that predict or moderate MDD treatment response or remission to escitalopram, sertraline or venlafaxine; and develop a model that incorporates multiple predictors and moderators.

The iSPOT-D study is a multi-center, international, randomized, prospective, open-label trial (1). It is enrolling 2016 MDD outpatients (ages 18–65) from primary or specialty care practices (672 per treatment arm; 672 age-, sex- and education-matched healthy controls). Study-eligible patients are antidepressant medication (ADM) naïve or washed-out with no protocol ADM contraindications. Baseline assessments include symptoms; distress; daily function; cognitive performance; electroencephalogram and event-related potentials; heart rate and genetic measures. A subset of these baseline assessments are repeated after eight weeks of treatment. Outcomes include the 17-item Hamilton Rating Scale for Depression (primary) and self-reported depressive symptoms, social functioning, quality of life, emotional regulation, and side-effect burden (secondary). Participants may then enter a naturalistic telephone follow-up at weeks 12, 16, 24 and 52. The first half of the sample will be used to identify potential predictors and moderators, and the second half to replicate and confirm.

First enrolment was in December 2008, and enrollment of the first 50% (1008 MDD participants) was completed in Dec 2010. iSPOT-D evaluates clinical and biological predictors of treatment response in the largest known sample of MDD collected worldwide.

Initial findings reveal a remission rate of 45.4% and a response rate of 62.6% after 6–8 weeks of treatment. Initial findings will be discussed including factors for response prediction and MDD subtype differences.