Prazosin has been an accepted treatment for patients with post-traumatic stress disorder (PTSD) who experience sleep disturbances, including nightmares. Results of a recent large randomized control trial did not find benefit of prazosin vs placebo in improving such outcomes. A meta-analysis that includes this most recent trial was conducted to examine the pooled effect of prazosin vs placebo on sleep disturbances and overall PTSD symptoms in patients with PTSD.

A systematic review of the published literature on trials comparing prazosin vs placebo for improvement of overall PTSD scores, nightmares, and sleep quality was conducted. Hedges’ g standardized mean differences (SMD) between prazosin and placebo were calculated for each outcome across studies.

Six randomized placebo-controlled studies representing 429 patients were included in the analysis, including two studies with a crossover design. Results showed prazosin significantly improved overall PTSD scores (SMD = −0.31; 95% confidence intervals [CI]: −0.62, −0.01), nightmares (SMD = −0.75; 95% CI: −1.24, −0.27), and sleep quality (SMD = −0.57; 95% CI: −1.02, −0.13). In the largest trial, prazosin showed a reduction in clinical outcome measures similar to past studies, but a relatively large placebo effect size, particularly for nightmares, contributed to no treatment differences.

Despite the results of a recent, large randomized study, pooled effect estimates show that prazosin has a statistically significant benefit on PTSD symptoms and sleep disturbances. Limitations that should be considered include heterogeneity of study design and study populations as well as the small number of studies conducted and included in this meta-analysis.