Perspective from Venu Menon, MD
July 22, 2015
4 min read

Two studies find bystander CPR, defibrillation linked to improved outcomes

Perspective from Venu Menon, MD
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When the rates of bystander-initiated CPR and defibrillation increased, outcomes improved for people with out-of-hospital cardiac arrest, according to results from two studies published in JAMA.

A study conducted in Japan found that an increased rate of bystander CPR and defibrillation between 2005 and 2012 was associated with greater likelihood of neurologically intact survival, while results from a study conducted in North Carolina indicated that an increase in bystander CPR and defibrillation between 2010 and 2013 was associated with improved odds of survival and an increase in bystander CPR was associated with increased odds of survival with favorable neurological outcome.

Japan study

Shinji Nakahara, MD, PhD, and colleagues estimated the associations between bystander interventions and changes in neurologically intact survival among patients in Japan with out-of-hospital cardiac arrest. They conducted a retrospective descriptive study of 167,912 patients with bystander-witnessed out-of-hospital cardiac arrest of presumed cardiac origin between 2005 and 2012. Patient data was collected from Japan’s national out-of-hospital cardiac arrest registry.

Nakahara, from the department of emergency medicine at Teikyo University School of Medicine, Tokyo, and colleagues evaluated the incidence of bystander prehospital intervention, neurologically intact survival (defined as Glasgow-Pittsburgh cerebral performance category score of 1 or 2 and overall performance category score of 1 or 2 at 1 month or at discharge) and the potential association between them.

The number of bystander-witnessed out-of-hospital cardiac arrests of presumed cardiac origin increased from 14 per 100,000 persons (95% CI, 13.8-14.2) in 2005 to 18.7 per 100,000 persons (95% CI, 18.4-18.9) in 2012, and the age-adjusted proportion of neurologically intact survival increased from 3.3% (95% CI, 3-3.5) to 8.2% (95% CI, 7.8-8.6).

During the study period, they wrote, rates of bystander CPR increased from 38.6% to 50.9%, rates of bystander-only defibrillation increased from 0.1% to 2.3%, and rates of combined bystander and emergency medical services defibrillation increased from 0.1% to 1.4%, whereas rates of EMS-only defibrillation decreased from 26.6% to 23.5%.

Compared with no bystander chest compression, bystander chest compression was associated with increased neurologically intact survival (8.4% vs. 4.1%; OR = 1.52; 95% CI, 1.45-1.6). Compared with EMS-only defibrillation, bystander-only defibrillation (40.7% vs. 15%; OR = 2.24; 95% CI, 1.93-2.61) and combined bystander and EMS defibrillation (30.5% vs. 15%; OR = 1.5; 95% CI, 1.31-1.71) were associated with increased neurologically intact survival, according to the researchers.

They also found that compared with EMS-only defibrillation, no defibrillation was associated with reduced survival (2% vs. 15%; OR = 0.43; 95% CI, 0.39-0.48).

North Carolina study

Carolina Malta Hansen, MD, and colleagues examined temporal changes in resuscitation performed by bystanders and first-responder prior to EMS arrival following statewide initiatives to improve resuscitation efforts in North Carolina between 2010 and 2013. These initiatives included training members of the general population in CPR and the use of automated external defibrillators, training first responders in team-based CPR including AED use and high-performance CPR, and training dispatch centers to recognize cardiac arrest.

They also examined the association between bystander and first-responder resuscitation efforts and survival and neurological outcome. The researchers defined survival with favorable neurological outcome as cerebral performance category 1 or 2.

The study included 4,961 patients with out-of-hospital cardiac arrest identified in the Cardiac Arrest Registry to Enhance Survival between 2010 and 2013.

Malta Hansen, from Duke Clinical Research Institute, and colleagues found that the administration of bystander CPR and first-responder defibrillation in combination increased from 14.1% (95% CI, 10.9-18.1) in 2010 to 23.1% (95% CI, 19.4-27.2) in 2013 (P < .01). Survival with favorable neurological outcome increased from 7.1% (95% CI, 5.8-8.8) in 2010 to 9.7% (95% CI, 8.2-11.4) in 2013 (P = .02) and was associated with bystander-initiated CPR, they wrote.

After adjustment for age and sex, bystander and first-responder interventions were associated with higher rates of survival to hospital discharge.

Compared with survival following EMS-initiated CPR and defibrillation (15.2%; 95% CI, 10.8-20.9), survival following bystander-initiated CPR and defibrillation (33.6%; 95% CI, 25.5-42.9; OR = 3.12; 95% CI, 1.78-5.46), survival following bystander CPR and first-responder defibrillation (24.2%; 95% CI, 20-29; OR = 1.7; 95% CI, 1.06-2.71) and survival following first-responder CPR and defibrillation (25.2%; 95% CI, 21.4-29.6; OR = 1.77; 95% CI, 1.13-2.77) were higher, Malta Hansen and colleagues wrote.

Ongoing efforts needed

“Despite increased knowledge and use of bystander CPR as well as improved survival over time, ongoing efforts are needed to improve outcomes after [out-of-hospital cardiac arrest],” Graham Nichol, MD, MPH, FRCP, and Francis Kim, MD, both from the University of Washington, Seattle, wrote in a related editorial. “Mortality after resuscitation from cardiac arrest continues to be high in many communities. Further improvements in outcomes will require additional coordinated efforts to improve resuscitation care.”

Francis Kim, MD

Francis Kim

They noted that the Institute of Medicine has released a report with recommendations to improve outcomes after cardiac arrest, and that the present studies “demonstrate the potential benefit these changes can have on resuscitation outcomes. Lay persons can improve outcomes after cardiac arrest in their community by participating in their system of care as well as supporting increased measurement and resuscitation research.” – by Erik Swain


Malta Hansen C, et al. JAMA. 2015;doi:10.1001/jama.2015.7938.

Nakahara S, et al. JAMA. 2015;doi:10.1001/jama.2015.8068.

Nichol G, Kim F. JAMA. 2015;doi:10.1001/jama.2015.7519.

Disclosures: The researchers from the Japan study report no relevant financial disclosures. Malta Hansen reports receiving grants from Helsefonden, Laerdal and TrygFonden. Three other researchers from the North Carolina study report financial ties with Laerdal and the Medtronic Foundation. Nichol reports receiving grants from Cardiac Science, HeartSine Technologies, Philips Healthcare, Physio-Control and Zoll and other support from Abiomed and Velomedix. Kim reports receiving support for scientific advisory from Mallinckrodt Pharmaceuticals.