Abstract Body: Background: Anaphylaxis is a life-threatening condition that can lead to out-of-hospital cardiac arrest (OHCA). Understanding the factors associated with neurological outcomes in anaphylaxis-induced OHCA may provide valuable clinical insights; however, evidence remains limited. Furthermore, the most effective treatments or the critical time window for achieving favorable neurological outcomes in anaphylaxis OHCA remain unclear.
Hypothesis: We hypothesized that specific clinical factors, including prehospital treatments (e.g., advanced airway management and adrenaline administration), are associated with favorable neurological outcomes in anaphylaxis OHCA. We also hypothesized that the time window for achieving a favorable outcome is short.
Aims: To identify clinical factors associated with favorable neurological outcomes and to describe the association between the CPR duration and probability of favorable outcome.
Methods: We analyzed OHCA cases from a nationwide Japanese registry (2005–2023), including all patients with cardiac arrest due to anaphylaxis. Neurological outcomes were categorized as favorable (Cerebral Performance Category [CPC] 1–2) or poor (CPC 3–5). Logistic regression analyses were performed to identify factors associated with favorable outcomes. A cubic spline curve was used to estimate the relationship between cardiac arrest duration and the probability of favorable outcomes.
Results: Among registered patients in adult, prevalence of anaphylaxis-induced OHCA was 0.16% (364/2,332,898). Among 364 patients, 106 (29.1%) achieved favorable neurological outcomes. These patients more frequently had witnessed arrests (91% vs. 73%, p<0.01), and prehospital return of spontaneous circulation (ROSC) (74% vs. 28%, p<0.01). Multivariable analysis showed that prehospital ROSC (adjusted odds ratio: 3.89, 95% confidence interval: 1.22–12.4) was significantly associated with favorable outcomes. However, prehospital airway management and adrenaline use were not significantly associated with favorable outcomes. Among patients with known cardiac arrest duration, the estimated durations corresponding to a 75%, 50%, and 25% probability of favorable outcome were 8, 13, and 18 minutes, respectively.
Conclusions: Anaphylaxis-induced OHCA can result in favorable neurological outcomes, particularly when ROSC is achieved early. These findings highlight the importance of rapid recognition and timely resuscitation in this population.