A systematic review and meta-analysis: prevalence of post-traumatic stress disorder in bipolar disorder

Background: Bipolar disorder (BD) is among the most prevalent psychiatric illnesses and accounts for a high disability-adjusted life-year (DALY) burden. Patients with BD show an increased likelihood of developing post-traumatic stress disorder (PTSD), a psychopathological condition resulting from exposure to a life-threatening or severely injurious event affecting oneself or others, defined by symptoms of re-experiencing, avoidance, negative alterations in cognition and mood, and hyperarousal. This comorbidity is associated with worse prognosis, requiring tailored treatment. To the best of our knowledge, no prior meta-analysis has quantified PTSD prevalence in BD. Methods: We conducted a systematic review and meta-analysis (PRISMA-guided) of studies reporting PTSD prevalence in BD (searches: PubMed, Scopus, Web of Science; through May 2025). Proportions were synthesized with a random-intercept logistic regression model on the logit scale. We estimated pooled current and lifetime prevalence, assessed heterogeneity (Q, I², τ²), examined small-study effects (funnel plots, Egger, Begg–Mazumdar), performed influence and outlier diagnostics (Baujat, Galbraith), and ran meta-regressions for prespecified moderators. Results: Thirty-five studies met criteria. Pooled current prevalence of PTSD in BD was 22.2% (95% CI 14.6–32.2; N=325,362). Pooled lifetime prevalence was 19.2% (95% CI 11.8–29.7; N=7,048). Between-study heterogeneity was considerable. Lifetime estimates showed evidence of small-study effects, whereas current estimates did not. After exclusion of outliers/influential studies, pooled estimates rose modestly and heterogeneity remained high. Meta-regressions found no significant moderation by mean age, sex composition, or study quality (all p>0.05). Geographic region did not differ in subgroup analyses. PTSD prevalence did not differ by BD subtype (BD-I vs BD-II). Conclusions: Approximately one in five individuals with BD meets criteria for PTSD, configuring a common phenotype with clinical consequences. Thus, in clinical practice routine PTSD screening, suicide-risk surveillance, and stepped multimodal care should be warranted and research should prioritize comparative treatment trials.