Nonwhite Cardiac Arrest Victims Are More Likely to Die Prehospital: Why?

Emergency medical service (EMS) agencies working in predominantly Black and Hispanic communities are less likely to get out-of-hospital cardiac arrest (OHCA) patients to the hospital alive than EMS agencies that work in white communities, with no clear reason why, a new study shows.

Factors that could be responsible for the differences, such as paramedic response times, CPR initiation, and use of an automated external defibrillator (AED) did not account for the differences in survival, noted Paul S. Chan, MD (Saint Luke’s Mid America Heart Institute, Kansas City, MO), the study’s senior author.

“The existing registry data do not provide the insights into understanding the survival differences we’re seeing. However, there were about 12 agencies in the cohort that worked in Black and Hispanic communities and have very high survival rates despite having probably more barriers to care than white communities,” he told TCTMD. “Understanding what's going on in those 12 communities would probably provide enormous insights, not only in terms of how EMS agencies can improve care across the board for all patients, but in particular for other EMS agencies that work in Black and Hispanic communities.”

In a prior study, Chan and colleagues found that Black and Hispanic OHCA patients are about 25% less likely than white patients to receive bystander CPR when a cardiac arrest occurs at home and 41% less likely to have a bystander attempt CPR on them when it occurs in public.

“We know that structural racism plays a role in all of this [that] is very difficult and oftentimes hard to define, but among the systematic things that are biased against Black and Hispanic communities is that even CPR training is oftentimes offered less frequently,” he told TCTMD. Other challenges for communities of color may include less funding for paramedics than in their white counterpart communities, as well as differences in the quality of EMS dispatch or dispatch CPR instructions.

The study was published last week in JAMA Internal Medicine.

No Appreciable EMS Differences

Using data from the multicenter CARES registry of OHCA in the US, Chan and colleagues led by Anezi I. Uzendu, MD (Saint Luke’s Hospital Mid America Heart Institute), examined data from 764 EMS agencies that responded to 258,342 OHCAs from 2015 through 2019. Of those, 10.7% served Black and Hispanic neighborhoods where the proportion of residents in those racial/ethnic groups ranged from 50.1% to 94.8% (median 63.5%). The median number of OHCA cases during the study period was higher for those serving Black and Hispanic catchment areas than those serving only white catchment areas (247 vs 117).

Patients had a median age of 63 years and 36% were female. Of patients for whom race and ethnicity data were known, 26.6% were Black and 7.7% were Hispanic. The majority of OHCAs occurred at home and had a presumed cardiac source with an initially detected rhythm that was nonshockable.

For each EMS agency, the researchers calculated the risk-standardized survival rate to hospital admission using a hierarchical logistic regression model with multiple variables as fixed effects. These included: age, sex, whether the arrest was witnessed, location, etiology, receipt of bystander CPR, and urbanicity of the arrest location.

OHCA patients from EMS agencies with Black and Hispanic catchment areas were more likely than those from agencies with white catchment areas to have an unwitnessed arrest and have asystole as the initially detected rhythm. They also were younger and less likely to receive bystander CPR or have ventricular fibrillation as the initially detected rhythm.

Just because it's a challenge doesn't mean that we don't call it out or we don't try and devote effort to it. Anezi I. Uzendu

After adjusting for patient and arrest characteristics, EMS agencies with Black and Hispanic catchment areas had nearly a 2% lower mean survival rate for OHCA compared with white catchment areas (P < 0.001).

While response times were similar between EMS serving Black and Hispanic catchment areas versus white areas, EMS in Black and Hispanic areas had had lower rates of termination of resuscitation for OHCAs that met futility criteria as well as those that did not meet futility criteria.

By survival quartiles, 39% of EMS agencies serving Black and Hispanic patients were in the lowest survival quartile, with only 14.6%—the 12 that Chan referenced—in the highest survival quartile.

A Challenge to Decipher

To TCTMD, Chan said the next phase of the research involves surveys and site visits to those 12 agencies to learn as much as possible about what they are doing differently that translates to better outcomes.

“Things like how they do their training and assessments of CPR competency, how often they do quality improvement, what kind of technologies are used in the actual resuscitation . . . those may provide more insight,” he added.

Although not a significant difference, there was less use of AEDs by first responders for patients treated in Black and Hispanic areas compared with white areas (20.8% vs 24.5%; P = 0.003), which may speak to access and/or bystanders not knowing how to use them.

“We know that bystander AED deployment improves survival by two- to threefold,” Uzendu told TCTMD. “In this study [AED use] didn’t change survival, but we know how important it is to have them accessible. Having a defibrillator on hand early could be a potential factor in survival.”

Overall, Uzendu said the study raises more questions than answers and adds to a glut of data on health inequities in people of color in the United States.

“As we gain more information, I think we may pick up multiple variables and see a lot of different effects of structural racism that are kind of interwoven in the conversations that we have,” he added. “It'll be challenging in a sense to decipher, and it might also be challenging to find easy solutions for it. But just because it's a challenge doesn't mean that we don't call it out or we don't try and devote effort to it.”