Thirty-day and one-year survival rates for out-of-hospital cardiac arrest tripled in Denmark between 2001 and 2010. The improvement coincides with the introduction of initiatives to educate the public about cardiopulmonary resuscitation (CPR), but other factors likely contributed as well.

Bystander CPR and 30-day survival rates for people who experienced out-of-hospital cardiac arrest were poor a decade ago in Denmark, which prompted a national campaign to increase awareness and teach the public how to perform CPR. In 2005, elementary schoolchildren received mandatory training in CPR, for instance, and in 2006, training was linked to getting a driver’s license.

But those were not the only strategies, wrote lead author Mads Wissenberg, MD, of Copenhagen University Hospital Gentofte in Hellerup, Denmark, and colleagues in the Oct. 2 issue of JAMA. The campaign also revamped processes used by emergency medical dispatchers, increased the number of automated external defibrillators (AEDs) outside of hospitals, expanded emergency medical service training and more.

Using the Danish Cardiac Arrest Registry and other data resources, Wissenberg et al looked at temporal trends in out-of-hospital cardiac arrest between 2001 and 2010. Overall, there were 19,468 patients with out-of-hospital cardiac arrests in the study group. The proportion of people who received bystander CPR jumped from 21.1 percent in 2001 to 44.9 percent in 2010. Rates of bystander CPR more than doubled, but AED use by a bystander remained low.

Over the decade, survival to hospital arrival increased from 7.9 percent to 21.8 percent; 30-day survival from 3.5 percent to 10.8 percent; and one-year survival from 2.9 percent to 10.2 percent.

Incidence of out-of-hospital cardiac arrest decreased from 40.4 to 34.4 per 100,000 persons between 2001 and 2010 yet survival at the hospital increased from 2.9 to 6.4 per 100,000 persons; 30-day survivors increased from 1.4 to 3.7 per 100,000 persons; and one-year survivors from 1.2 to 3.5 per 100,000 persons.   

“[T]he reason for improved survival is probably multifactorial and most likely related to improvements in each of the links in the chain of survival, as well as other factors that influence survival,” Wissenberg et al wrote. “This notion is supported by the observation that 30-day survival increased among patients both with and without bystander CPR.”

The AED findings showed a very modest improvement in use by bystanders, from 1.1 percent in 2001 to 2.2 percent in 2010. They wrote that was not a surprise. Denmark launched efforts to place more AEDs outside the hospital during the last year of the study period, and most out-of-hospital cardiac arrests occur homes and not public places.

The authors proposed that the gains observed likely are influenced by the training and other initiatives but because theirs was an observational study, the results do not establish a causal relationship.