Antidepressants versus placebo for generalised anxiety disorder (GAD)

Summary & key facts

This Cochrane review pooled 37 randomized trials with 12,226 adults who had moderate to severe generalized anxiety disorder (GAD). It found antidepressants were more effective than placebo at improving anxiety symptoms, with high confidence in the main results. Overall dropout rates were similar between antidepressants and placebo, but fewer people on antidepressants stopped because the drug did not work and more stopped because of side effects. The trials lasted 4–28 weeks and mostly excluded people with serious medical illnesses.

Key facts:

• The review included 37 randomized controlled trials with 12,226 participants.
• Antidepressants increased the chance of a treatment response (≥50% reduction on the HAM‑A) versus placebo: risk ratio (RR) 1.41, 95% CI 1.29 to 1.55 (20 studies, 7,267 participants).
• The number needed to treat for one additional beneficial outcome (NNT) was 7 (95% CI 5 to 9) for treatment response.
• Overall acceptability (dropouts for any reason) was similar: RR 1.03, 95% CI 0.93 to 1.14 (33 studies, 11,294 participants).
• Fewer participants dropped out because of lack of efficacy on antidepressants versus placebo: RR 0.41, 95% CI 0.33 to 0.50 (29 studies, 11,007 participants); NNT for benefit 27 (95% CI 24 to 32).
• More participants dropped out because of adverse effects on antidepressants versus placebo: RR 2.18, 95% CI 1.81 to 2.61 (32 studies, 11,793 participants); number needed to harm (NNH) 17 (95% CI 13 to 112).
• The evidence for these main outcomes was rated as high certainty by the review authors.
• Trials ran from 4 to 28 weeks and mostly enrolled adults without serious medical comorbidities; few trials included people with other psychiatric disorders as well.

Abstract

This review added to the growing literature on antidepressants in the treatment of GAD. We have high confidence that antidepressants are more effective than placebo at improving treatment response and that antidepressants have similar acceptability to placebo. Fewer participants dropped out due to a lack of efficacy in the antidepressant group compared to the placebo group and more participants dropped out due to adverse effects in the antidepressant group compared to placebo. We are highly confident in this evidence. This review identified some important gaps in the literature on antidepressants for GAD and can be used as a tool to guide future research. Future studies may be more transparent with their methodology and outcome reporting. Future reviews may also include people with comorbidities, and explore other sources of heterogeneity.

Topics

Anxiety, Depression, Psychometrics, Treatment, Cognitive Processes Child and Adolescent Psychosocial and Emotional Development Perfectionism, Procrastination, Anxiety Studies

Categories

Experimental and Cognitive Psychology Psychology Social Sciences

Tags

Adverse effect Alternative medicine Antidepressant Anxiety Generalized anxiety disorder Internal medicine Medicine Pathology Placebo Psychiatry Psychopharmacology Randomized controlled trial Tolerability