Many factors influence the likelihood of bystander cardiopulmonary resuscitation (BCPR) after out-of-hospital cardiac arrest (OHCA), but gender disparities in prehospital care remain under-examined, particularly in relation to the bystander’s connection to the patient.

The objective of this study was to evaluate the association between gender and the likelihood of receiving BCPR in OHCA. The primary outcome of the study was to examine differences in BCPR rates among men and women who experienced OHCA. The secondary outcome was to investigate whether bystanders were more likely to provide CPR based on their relationship to the victim, comparing “true” layperson CPR to CPR administered by family members or friends and how these rates differed between men and women.

This retrospective prehospital chart review included all encounters from a single urban Emergency Medical Services (EMS) agency with a cardiac arrest prior to EMS arrival from January 1, 2017 through June 30, 2022 (n = 701). For each encounter, the presence or absence of BCPR was recorded, along with the relation of the bystander to the patient. “True” BCPR was defined as CPR performed by a layperson unknown to the patient. Patients were excluded if they exhibited signs of obvious death, were physically inaccessible to bystanders, had CPR initiated by trained facility staff or police, had a do not resuscitate (DNR) order present on EMS arrival, received CPR but were not in cardiac arrest, or were younger than 18 years old (n = 174). Odds ratios (OR) with 95% confidence intervals (CI) were used to evaluate data, with statistical significance defined at P < .05.

The study examined 701 cardiac arrest encounters: 250 female (35.7%) and 451 male (64.3%). Overall, men (n = 123; 27.3%) were more likely to receive BCPR than women (n = 48; 19.2%); OR = 1.58; 95%CI, 1.08-2.30; P = .02. Among those who received BCPR, women were significantly more likely to have received it from someone they knew (83.3% versus 65.9%; OR = 2.59; 95%CI, 1.11-6.04; P = .03) while men were more likely to receive “true” layperson BCPR.

This study identifies significant gender disparities in prehospital BCPR and highlights an association between the bystander’s relationship to the patient and the likelihood of intervention.

While the overall survival rate for out-of-hospital cardiac arrest (OHCA) is low, ranging from 5%-10%, several characteristics have been shown to decrease mortality, such as presence of bystander cardiopulmonary resuscitation (CPR), witnessed vs unwitnessed events, and favorable initial rhythm (VF/VT). More recently, studies have shown that modified CPR algorithms, such as chest-compression only or cardio-cerebral resuscitation, can further increase survival rates in OHCA. Most of these studies have included only OHCA patients with “presumed cardiac etiology,” on the assumption that airway management is of lesser impact than chest compressions in these patients. However, prehospital personnel often lack objective and consistent criteria to assess whether an OHCA is of cardiac or non-cardiac etiology.

The relative proportions of cardiac vs non-cardiac etiology in published data sets of OHCA in the peer-reviewed literature were examined in order to assess the variability of prehospital clinical etiology assessment.

A Medline (US National Library of Medicine, National Institutes of Health; Bethesda, Maryland USA) search was performed using the subject headings “OHCA” and “Emergency Medical Services” (EMS). Studies were included if they reported prevalence of cardiac etiology among OHCA in the entire patient sample, or in all arms of a comparison study. Studies that either did not report etiology of OHCA, or that excluded all cardiac or non-cardiac etiologies prior to reporting clinical data, were excluded.

Twenty-four studies were identified, containing 27 datasets of OHCA which reported the prevalence of presumed cardiac vs non-cardiac etiology. These 27 datasets were drawn from 15 different countries. The prevalence of cardiac etiology among OHCA ranged from 50% to 91%. No obvious patterns were found regarding database size, year of publication, or global region (continent) of origin.

There exists significant variation in published rates of cardiac etiology among OHCAs. While some of this variation likely reflects different actual rates of cardiac etiologies in the sampled populations, varying definitions of cardiac etiology among prehospital personnel or varying implementation of existing definitions may also play a role. Different proportions of cardiac vs non-cardiac etiology of OHCA in a sample could result in entirely different interpretations of data. A more specific consensus definition of cardiac etiology than that which currently exists in the Utstein template may provide better guidance to prehospital personnel and EMS researchers in the future.

CarterRM , ConeDC . When is a Cardiac Arrest Non-Cardiac?Prehosp Disaster Med. 2017;32(5):523–527.