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From the Journals

Outcomes of Anaphylaxis vs Cardiac OHCA: New Insights

Researchers have found that out-of-hospital cardiac arrests caused by anaphylaxis are associated with better neurological outcomes and higher survival rates compared to those caused by cardiac conditions.

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Patients experiencing out-of-hospital cardiac arrests caused by anaphylaxis may be twice as likely to achieve favorable neurologic outcomes at 1 month compared with those with cardiac causes, according to a recent study. 

In the study, published in BMJ Open, investigators examined the neurologic outcomes and survival rates of patients experiencing out-of-hospital cardiac arrests (OHCA) caused by anaphylaxis (OHCA-A) compared with cardiac causes (OHCA-C). Using 2012 to 2021 data from the All-Japan Utstein Registry, the retrospective, nationwide observational study included 153,890 patients, 331 of whom experienced OHCA-A and 153,559 of whom experienced OHCA-C.

The investigators aimed to assess favorable neurologic outcomes at 1 month, defined as a Glasgow–Pittsburgh Cerebral Performance Scale score of 1 or 2, as the primary outcome. Survival at 1 month was evaluated as the secondary outcome. To account for confounding factors, multivariable logistic regression analysis and propensity score matching (PSM) were utilized. The analysis adjusted for variables including age, sex, bystander cardiopulmonary resuscitation, initial rhythm, and emergency medical services response time.

The patients with OHCA-A demonstrated significantly better outcomes compared with those with OHCA-C. Favorable neurologic outcomes were achieved in 24.2% of OHCA-A cases compared with 11.7% of OHCA-C cases (P < .001). Survival rates at 1 month were also higher in the OHCA-A group (33.2% vs 16.1%, P < .001). Multivariable regression analysis revealed that OHCA-A was independently associated with improved neurologic outcomes (adjusted odds ratio [OR] = 1.86, 95% confidence interval [CI] = 1.34–2.59) and survival at 1 month (adjusted OR = 2.43, 95% CI = 1.78–3.31). In a sensitivity analysis using a 1:4 PSM cohort, OHCA-A maintained a higher likelihood of favorable neurologic outcomes (OR = 2.91, 95% CI = 1.83–4.65).

The investigators noted that the improved outcomes in OHCA-A may be attributed to the pathophysiology of anaphylaxis and the critical role of epinephrine in its management. However, limitations of the study included the lack of posthospital treatment data and potential variability in diagnosing the etiology of cardiac arrests. The findings suggested that patients with OHCA-A warrant aggressive resuscitation and early intervention to optimize neurologic outcomes.

Full disclosures can be found in the published study.