The Effectiveness of Sertraline in Patients Who Have Had Inadequate Response to Escitalopram

Inclusion Criteria: * Primary DSM-IV diagnosis of Major Depressive episode of MDD without psychotic symptoms. Additional axis I diagnoses will be permitted only if they are identified as secondary diagnoses * Ham-D 21 item score of greater than or equal to 18 * Age 18 and above * Ability and willingness to provide consent for participation * Failure to respond to escitalopram Exclusion Criteria: * Diagnosis of Bipolar Disorder or any psychotic disorder * Alcohol or drug abuse or dependence currently or in the last 6 months * A history of non-response or intolerance to sertraline at least 50 mg. for at least 4 weeks or more * Concomitant use of another antidepressant or use of an antidepressant within 2 weeks of baseline (4 weeks for fluoxetine) * Use within 1 week of baseline, or concomitant use of any psychotropics with the exception of zolpidem for sleep * Use within 4 weeks of baseline or concomitant use of benzodiazepines with the exception of PRN use of diazepam 10 mg/day or its equivalent * Presence of serious and/or unstable medical condition * Score of 3 or 4 on the suicide item (item 3) of the Ham-D scale * Known sensitivity of sertraline