Number of community first responders needed for quick response times to cardiac arrest: a nationwide study

Current resuscitation guidelines recommend activating a community first responder (CFR) system for out-of-hospital cardiac arrest. Although such systems are widely implemented, evidence on how the number of available CFRs affects system performance is very limited. This study assessed how many available CFRs are required to consistently achieve CFR response times under 5 min.

Activations of the Danish nationwide CFR system from February 2018 to August 2024 were grouped by the number of available CFRs per 100,000 residents. Response times for the first-arriving CFR and the first-arriving CFR bringing an automated external defibrillator (AED) were calculated from the coordinates of moving CFRs.

We analyzed 12,806 CFR system activations. As the number of available CFRs increased from 300-399 to 800-899 per 100,000 residents, the percentage of activations with a response time under 5 min for the first-arriving CFR increased from 33% to 46% (an absolute increase of 13%, 95% CI [5%, 21%]) and for the first-arriving CFR bringing an AED from 7% to 29% (an absolute increase of 23%, 95% CI [15%, 31%]).

The likelihood of CFR response times under 5 min increased significantly with the number of available CFRs. At around 800 available CFRs per 100,000 residents, a response time under 5 min for the first-arriving CFR was achieved in almost half of system activations, and for the first-arriving CFR bringing an AED in almost one-third of system activations. This shows the importance of recruiting enough CFRs to ensure quick response times.