Characteristics and outcomes after out-of-hospital cardiac arrests in individuals with pre-existing psychiatric conditions, compared to those without

• Individuals with a prior psychiatric diagnosis had substantially lower 30-day and long-term survival following out-of-hospital cardiac arrest (OHCA). • Psychiatric comorbidity was particularly common among younger patients, in whom more than half had a prior psychiatric diagnosis. • Arrest characteristics differed, with lower rates of witnessed arrests and non-shockable initial rhythms more frequent among individuals with psychiatric conditions, despite similar rates of bystander CPR. Background/purpose: Individuals with psychiatric conditions have increased cardiovascular morbidity and mortality, yet outcomes following out-of-hospital cardiac arrest (OHCA) in this population remain insufficiently characterized. We aimed to investigate the association between pre-existing psychiatric conditions and outcomes after OHCA in a nationwide Swedish cohort. Materials and methods: We conducted a registry-based cohort study including all individuals ≥16 years with OHCA reported to the Swedish Registry for Cardiopulmonary Resuscitation (2010–2020). Psychiatric conditions were identified using ICD-10 codes and categorized into major diagnostic groups. The primary outcome was 30-day survival. Secondary outcomes included neurological status at discharge (CPC score), arrest characteristics, and long-term survival. Logistic regression models adjusted for age and sex were used, and analyses were stratified by initial rhythm. Results: Among 53,981 individuals, 13,777 (26%) had a prior psychiatric diagnosis. Cardiac arrests in individuals with psychiatric conditions were less often witnessed and less likely to present with a shockable rhythm, despite similar rates of bystander CPR. Intoxication and suicide were markedly more common presumed causes, particularly among younger adults, in whom over half had a psychiatric diagnosis. Thirty-day survival was lower in individuals with psychiatric conditions (9% vs. 12%; adjusted OR 0.52, 95% CI 0.48-0.56). In stratified analyses, this association was evident in shockable but not non-shockable rhythms. Neurological outcomes among survivors were largely comparable. Conclusion: Pre-existing psychiatric conditions are associated with lower survival after OHCA, largely driven by differences in arrest characteristics and etiology rather than bystander response. These findings highlight a vulnerable population and underscore the importance of targeted prevention and early recognition strategies. Keywords: Out-of-Hospital Cardiac Arrest (OHCA), Psychiatric diagnosis, Young Adults, 30-day survival, Swedish Cardiopulmonary Registry (SRCR), Emergency Medicine