Exploring Sex, Gender, and Survival Differences in CPR and Cardiovascular Disease

Show Notes for Episode Twelve of seX & whY: Sex and Gender Differences in CPR Part 1 & 2

Host: Jeannette Wolfe Guest: Dr Justin Morgenstern

Two big databases surrounding cardiac arrest

• Cares- Cardiac Arrest Registry to Enhance Survival which is based on information from national EMS data input via the NEMSIS national EMS information system
• ROC- Resuscitation Outcomes Consortium (ROC) 2011-2015. The ROC is a network of National Institutes of Health -funded clinical trial network evaluating out of hospital cardiac arrests that collects data from 11 different sites around the United States

Here are two great articles that cover this material in depth

• AHA 2019 stats
• When the Female Heart Stops: Sex and Gender Differences in Out-of-Hospital Cardiac Arrest Epidemiology and Resuscitation

What we know

• Over 350,000 people will have a cardiac arrest this year
• Men account for about 2/3 of OHCA
  • average age for men 66
  • average age for women 72
• About 20-25% will occur in public place
  • Men are proportionately more likely to collapse in public place than women (19% versus 8.4% in one study)
• About half of cardiac arrests are witnessed (about 37% by layperson and 12% by EMS)
  • compared to men, women have higher rate of unwitnessed arrest.

(46% vs 52%  in one study)

• Bystander CPR doubles to triples rates of survival
• Rates of bystander CPR are highly variable and depend heavily upon where you live and its demographics with CPR being less likely to be started in predominately minority and lower socioeconomic communities. Overall, it appears that about 35-40% or cardiac arrests will get bystander CPR
• Where you live is also dramatically associated with your rates of leaving the hospital neurologically intact.
  • One study that examined 132 different counties showed, depending upon the county,  functional recovery rates ranging from 0.8%-20% (which again, is likely heavily influenced by  variations in CPR and AED use.)
• CARES data bank stats suggest that out of hospital cardiac arrest (OHCA)
  • 28% live to hospital
  • 8% leave neurologically intact
• Usually less than 20% of initial rhythms of OHCA are shockable
  • though sex difference here also

(one study 29% men vs women 16% with initial shockable rhythm)

• Per one survey  about 2/3 of people has some type of CPR training with 20% being currently trained
  • CPR training noted to be lower amongst Hispanics, elderly, lower income, less formally educated
• Of those trained in CPR only about 1/3 of people will actually step up and do it when indicated

First study

Gender disparities among adult recipients of bystander cardiopulmonary resuscitations in the Public from Audrey Blewer in Cir Cardiovasc Qual Outcomes 2018

Primary study question- is there an association between an individual’s biological sex and the likelihood they will receive bystander CPR

Resuscitation Outcomes Consortium (ROC) 2011-2015

This was a retrospective analysis of data collected in a prospectively for several clinical trials in out of hospital cardiac arrests from 7 of these sites.

Exclusion:

Traumatic arrest

Occurs in a residential institution or hospital

Less than 18

CPR initiated by someone who was not a layperson (police EMS doc)

The variable they used in logistic regression modeling included whether event was witnessed, location, layperson CPR, time of event, and basic demographics including age, race, gender

Nontraumatic out of hospital cardiac arrests

19331 events

Mean age 64

63% male

17% public location (3297)

82% private (15788)

Overall 37% received CPR (38% of men and 35% of women)

If collapse occurred in public place

• 45% of men and 39% of women

If collapse occurred in private place

• 36% of men and 35% of women received CPR

Overall: Males had 29% increased odds of survival

Bottom line: If you have a OHCA in public you are about 6% more likely to receive CPR if you are a man than a woman

This is not the only study showing gender differences in CPR here is a   Netherland study and an avatar study which also highlight these differences.

There are also studies suggesting subtle gender differences in EMS treatment of chest pain/cardiac arrest:

• time to CPR, time to first rhythm strip, IV placement, medication administration
• likelihood of getting lights and sirens or aspirin

Ok so why is that happening?

So first let’s talk about some general barriers to stepping up and doing CPR in public-

A 2008 study by Swor in Annals of EM interviewed almost 700 bystanders to an OHCA. Although about ½ of the bystanders had previous CPR training only about 20% actually started doing CPR.

Cited barriers to doing CPR included:

- feeling of panic (reported by about 38% )

- concern of doing it incorrectly (9%)

- concern they could cause harm (1%)

- reluctance to do mouth to mouth (1%)

In another study which surveyed community members from areas in which there were low rates of bystander CPR to understand why the rates were so low, answers included:  

- fear of getting sued

- emotional overtones of the situation

- lack of knowledge

- situational concerns 

A different study suggested that disagreeable physical characteristics- read dentures and vomit-  might hamper CPR initiation.

Overall you are more likely to step up and do CPR if

• CPR training within last 5 years (OR 6.6)
• in public (OR 3.1)
• see them collapse (OR 2.3);
• bystander has greater than a high school education (OR 2.0)

So the next question is, are these the reasons why there is a gender difference in who gets bystander CPR or are there additional factors to consider.

Second study

Public Perceptions on Why Women Receive Less Bystander Cardiopulmonary Resuscitation than Men in Out of Hospital Cardiac Arrest

Perman Circulation 2019

 Primary Question- what are the public perceptions as to why women are less likely to get bystander CPR?                                            

Methods- Electric survey via Amazon’s crowdsourcing platform- Mechanical Turk. Participants were English, >18 and familiar with CPR principles

Mechanical Turk- have “master users” people achieve this rate by apparently having a history of completing other surveys out appropriately in the past (essentially successfully answering planted “attention” surveys which suggests that they are actually reading the surveys)

Participants were asked 11 multiple choice questions and one free text- “ Do you have any ideas on why women may be less likely to receive CPR than men when they collapse in public?” Free text responses were coded and major themes were identified by using an inductive qualitative method.  

548 subjects

542 completed surveys

average age 38

equal number of males and females about 1% of participants were transgender

81% White 7% Black 6% Asian 3% Hispanic

45% college diploma

½ were trained at some time in CPR (top reasons for training were cited a work or volunteer related requirement)

24 had actually done CPR on a collapsed person-

Three major themes evolving:

1) Sexualization of woman’s bodies (40% of men mentioned versus 29% of women)

     - fear of making incidental contact with a woman’s breast

“I think that people are afraid to touch the breast region, so hesitate to administer CPR”

     - fear of being wrongfully accused of sexual abuse

“Bystanders, especially male bystanders, may be afraid to touch women especially in the chest area... anxious that their help my be unnecessary and therefore touching may be misconstrued”

“Men are afraid of seeming like perverts”

2) Perception that women are weaker and frailer and thus at greater risk for injury if CPR was not really needed

“People might be afraid of hurting them since women tend to be smaller and more fragile looking than men”

3)  Misperception of what actual distress looks like in females

”They are not known to have as many heart attacks in public, they are known to be healthier”

 “ Maybe people assume they are being dramatic and overreacting so CPR isn’t needed” 

Interestingly in the open- ended responses it was frequently implied by use of pronouns that the bystander initiating CPR would be a man. Along these lines, this European paper hints that gender related issues may also influence who steps up to start CPR.

My (liberal) summary of paper:

“Look I’m not super thrilled about the idea of touching a woman’s breast and quite frankly I’m a little scared about being accused of sexual assault.  And also, if I’m honest, I’m a little suspicious that the woman might be collapsing from something less serious, because most cardiac arrests seem to happen in guys. Finally, if I do start CPR on a woman and they really didn’t need it, I’m afraid I might accidentally physically hurt her.

Five take home points

• As more than 60% of cardiac arrests do not get bystander CPR, please consider sending out these CPR videos from the American Heart Association and The British Heart Foundation to friends or family members to teach and/or reinforce basic CPR principles as good CPR doubles to triples survival rates.
• There are innate biological sex differences associated with out of hospital cardiac arrests including: 2/3 of cardiac arrest occur in men who collapse on average collapse about 7-10 years earlier than women. Men are also more likely to have an initial shockable rhythm.
• Gender related issues, which can notoriously sneak under the radar if we don’t intentionally look for them, can also impact cardiac arrests. The study we talked about today suggested about a 5-6% absolute differences in public bystander CPR rates with men receiving more CPR. Concerningly there is similar research suggesting gender based inequities of both the EMS and hospital management level of cardiac arrest and we will continue this discussion in part 2 of our series. Although more deductive research is needed, there are hints that some of these gender related CPR differences are rooted in concerns surrounding sexuality, perceptions about fragility and misconceptions that collapsing women are unlikely to be having a cardiac arrest.
• The first step to gender- based gaps in cardiac arrest is to simply validate they exist. If you teach CPR, recognize and normalize that for some learners, invading someone’s personal space can feel totally awkward and then encourage them to mentally rehearse different scenarios in which they visualize themselves successfully starting CPR.  Using tools like the womanikin can help.
• As it appears that only about 30% of people who already know CPR, will actually step up to do it, we must work on ways to close this gap. Considering the introduction of stress inoculation and introducing things like Mike Lauria’s breath, talk, see and focus technique holds promise.

Other references

High Sensitivity Troponin and Gender Differences in treatment after ACS

North Carolina’s Heart Rescue Intervention

Article about CPR and Good Samaritan laws