Out of hospital cardiac arrest outcomes’ determinants: an Italian retrospective cohort study

Abstract Out-of-hospital cardiac arrest (OHCA) is the most time-critical and time-dependent medical emergency and is associated with low survival rates and poor neurological outcomes at the global level. This study aims at evaluating post-OHCA intra-hospital mortality risk according to patient’s characteristics and emergency health service management (EMS), including level of care of first-admission hospital. We conducted a retrospective cohort study based on data from the Lombardia Cardiac Arrest Registry (Lombardia CARe), the most complete nationwide out-of-hospital cardiac arrest (OHCA) registry in Italy. Out of 12,581 patients registered from 2015 to 2022, we considered 1,382 OHCA patients admitted alive to hospital and survived more than 24 hours. We estimated risk ratios (RRs) and corresponding 95% confidence intervals (CI) of post-OHCA intra-hospital mortality through log-binomial regression models adjusted by patients’ and EMS characteristics. The study population consisted mainly of males (66.6%), most aged 60-69 years (24.7%) and 70-79 years (23.7%). Presenting rhythm was non-shockable in 49.9% of patients, EMS intervention time was less than 10 minutes for 30.3% of patients, and cardiopulmonary resuscitation (CPR) was performed for less than 15 minutes in 29.9%. Moreover, 61.6% of subjects (n = 852) died during hospital admission. Post-OHCA intra-hospital mortality risk is 27% higher for non-shockable presenting rhythm (RR 1.27, 95% CI 1.19-1.35 vs. shockable rhythm) and 39% higher for longer CPR time (RR 1.39, 95% CI 1.28-1.52 for 45 minutes or more vs. <15 minutes, p-value for trend <0.01). Patients who accessed a secondary vs. tertiary care hospital were more frequently older, with a non-shockable presenting rhythm and longer EMS intervention time. Our findings showed that patients’ outcomes are associated with intrinsic OHCA characteristics and Health System’s resources are utilised as efficiently as possible. Key messages • Intra-hospital mortality risk was 27% higher among OHCA patients with non-shockable presenting rhythm, net of the hospital level of care. • Early defibrillation of shockable rhythms is associated with improved survival, so ensure timely access to defibrillators and implement education and training programs to the first CPR is pivotal.