Treatment effect of bystander CPR varies by race, sex
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Key takeaways:
- For patients with out-of-hospital cardiac arrest, bystander CPR improved survival to hospital discharge.
- The degree of improvement varied by race and sex, with the effect smallest for Black patients and women.
For patients with out-of-hospital cardiac arrest, bystander CPR improved rates of survival to hospital discharge, but the degree varied by race and sex, researchers reported in Circulation.
“The reason why we looked at ... when somebody does get bystander CPR, do they have the same benefit across race and sex groups, is to try to better understand the complexity of the intervention of bystander CPR,” Paul S. Chan, MD, MSc, cardiologist at Saint Luke’s Mid America Heart Institute and professor of medicine at University of Missouri-Kansas City School of Medicine, told Healio. “Is it just a yes/no answer that all bystander CPR is created equally? Or are there differences that may be obscured by just answering yes/no? I don’t think there has been enough attention to better understand when bystander CPR is delivered, is it delivered effectively for all people.”
Chan and colleagues analyzed data from 623,342 U.S. patients with nontraumatic out-of-hospital cardiac arrest (mean age, 62 years; 36% women; 50% non-Hispanic white) who were included in the CARES registry from 2013 to 2022 to determine whether the extent of bystander CPR improved rates of survival to hospital discharge varied by race and sex.
In the overall cohort, 9.3% of patients survived to hospital discharge, Chan and colleagues found.
Survival benefit from bystander CPR
Bystander CPR was associated with improved rates of survival to hospital discharge (adjusted OR = 1.28; 95% CI, 1.25-1.3; P < .001) and favorable neurological survival, defined as Cerebral Performance Category score of 1 or 2 at discharge, (aOR = 1.37; 95% CI, 1.34-1.4; P < .001) compared with no bystander CPR in the overall cohort.
However, Chan and colleagues found that the degree of improvement in survival to hospital discharge due to bystander CPR varied across race/ethnicity:
- Native American: aOR = 1.4; 95% CI, 1.2-1.9;
- non-Hispanic white: aOR = 1.33; 95% CI, 1.3-1.37;
- unknown race: aOR = 1.31; 95% CI, 1.25-1.36;
- Hispanic: aOR = 1.29; 95% CI, 1.2-1.39;
- Asian: aOR = 1.27; 95% CI, 1.12-1.42; and
- non-Hispanic Black: aOR = 1.09; 95% CI, 1.04-1.14; P for interaction < .001.
In addition, the researchers found that the association between bystander CPR and survival to hospital discharge was higher in men (aOR = 1.35; 95% CI, 1.31-1.38) than in women (aOR = 1.15; 95% CI, 1.12-1.19; P for interaction < .001).
“We had hints from prior work that the results may differ by sex after a cardiac arrest,” Chan told Healio. “This is the first study that has looked at a race comparison. I don’t think anything surprises us in terms of disparities in interventions, but it is still startling to find that the benefit can be so widely varied by race and sex. The magnitude of the differences seemed to be more striking than we had anticipated. We found that Black women had the least amount of benefit, to the point where [the survival benefit from bystander CPR] was barely discernible at all, and white men had the greatest benefit.”
The weaker association between bystander CPR and survival to hospital discharge in Black individuals and in women was consistent across neighborhood race/ethnicity and income strata, Chan and colleagues wrote.
The variation in bystander CPR benefit across race and sex was similar for the outcome of favorable neurological survival.
Further study needed
Possible explanations for the disparities include bystander hesitancy to put hands on women, perception of women as more fragile and more likely to be injured by CPR, physiological differences that may render chest compressions less effective in some patients and a greater burden of comorbidities in Black patients, but there are not yet definitive answers, Chan said.
Another factor that could be in play, Chan said, is that bystander CPR begun immediately by someone trained in it is more effective than bystander CPR begun after a 911 call by someone who is not trained in it and is relying on instructions from the dispatcher.
“If there is a higher rate of 911-initiated bystander CPR in Black communities or Black individuals who have cardiac arrest, this could partly explain the findings that the benefit is not as strong in Black individuals with cardiac arrest,” he said. “But we don’t have the granularity of that data, at least in the United States. That deserves further study.”
The first step to reduce the disparities is to increase rates of CPR training in communities with historically low rates of training, and to make CPR training more affordable to people with lower income, Chan told Healio.
“Another step is to get dispatchers in vulnerable and minority communities better trained in delivering instructions for bystander CPR,” he said. “We should then also better understand whether the mass campaigns that are a shorter version of the 4-hour CPR training are as effective. Those tend to include short videos or shorter courses and to be done to reach communities that have not been reached. Such outreach is critically important to do, but it’s less clear how much retention people have in terms of doing CPR and the quality of the CPR that’s delivered. We need more information to determine whether the mass campaigns and nontraditional CPR training are just as effective as regular CPR training.”
For more information:
Paul S. Chan, MD, MSc, can be reached at pchan@saint-lukes.org.
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