The epidemiology of out-of-hospital cardiac arrest (OHCA) is a significant public health issue, and large-sample studies on such events within China are relatively limited. This study utilizes the Utstein model to evaluate and analyze the epidemiological characteristics of OHCA in Shenzhen from 2011 to 2018. By reviewing ambulance dispatch records and prehospital medical records from the Shenzhen Emergency Medical Center between 2011 and 2018, the study analyzed epidemiological characteristics and reported the results. The main indicators of the study include demographic characteristics such as the gender, age, location of occurrence, key time points, vital signs, chief complaints, and diagnoses of the cases. It also covers prehospital emergency treatment processes, including whether bystanders performed CPR, initial electrocardiogram results, intravenous access establishment, use of epinephrine, defibrillation, tracheal intubation, and other interventions, as well as the outcomes of resuscitation.

Inclusion Criteria:

• Cases with secondary diagnoses containing only the diagnostic keywords "cardiac arrest" and "sudden death"

Exclusion Criteria:

• 1. Cases with suicide, drowning, advanced cancer, trauma, shock, poisoning, cerebrovascular accidents, etc. 2.Cases with duplicate records for gender, age, time of call, pick-up and drop-off address, and initial diagnosis.

The data source consists of ambulance dispatch records and prehospital medical records documented by the Shenzhen Emergency Medical Center from 2011 to 2018.