The STAR*D study is a ground-breaking, large-scale study of over 4,000 adults with treatment-resistant depression at 41 different locations in the U.S. As part of the study 2,876 people received the antidepressant citalopram. In the second phase of the study those people (1,292) who had failed to improve after taking citalopram for 14 weeks were then randomly assigned to take another antidepressant or a combination of citalopram and another drug. As part of the trial participants were asked about their anxiety levels. Approximately 53% of the sample had clinical anxiety problems and for those people remission was significantly less likely and took longer to occur. Ratings of drug side effects were also significantly greater in the anxious group. Changing medication or augmenting citalopram with another drug were also significantly less effective in anxious people.
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