Major depression is usually very hard to treat. Studies have shown that only 11-30% of patients reach remission with initial treatment, even after 8-12 months. Most patients require a 'second-step' treatment but there is little information about the relative effectiveness of different drugs as a second step and prescribing tends to be done on a 'trial-and-error' basis. A U.S. study of 727 patients, between the ages of 18 and 75 looked at which factors were associated with a remission in patients being treated with 'second-step' medication. The researchers found that remission was more likely among participants who were White, employed, cohabiting or married and who had made no prior suicide attempts. Remission was less likely among patients who were also suffering from anxiety, obsessive-compulsiv disorder, panic disorder, post-traumatic stress disorder and social phobia. People with substance abuse problems were also less likely to improve when treated with a 'second-step' drug.
Rush, John A. ... [et al] - Selecting among second-step antidepressant medication monotherapies: predictive value of clinical, demographic, or first-step treatment features Archives of General Psychiatry August 2008, 65(8), 870-881