Some studies have suggested that people who suffer from anxiety as well as depression respond less well to treatments with antidepressants. J. Craig Nelson from the University of California, San Francisco reviewed 11 studies into the effectiveness of duloxetine at treating depression. The studies covered a total of 2,841 people of whom 1,326 were classified as anxious. Duloxetine was found to be more effective than a placebo and have better response and remission rates, and the drug was just as effective for people with anxiety.
Nelson, J. Craig - Anxiety does not predict response to duloxetine in major depression: results of a pooled analysis of individual patient data from 11 placebo-controlled trials Depression and Anxiety January 2010, 27(1), 12-18