Association between population density and reported incidence, characteristics and outcome after out-of-hospital cardiac arrest in Sweden

Aim: To describe the reported incidence of out of hospital cardiac arrest (OHCA) and the characteristics and outcome after OHCA in relation to population density in Sweden.

Methods: All patients participating in the Swedish Cardiac Arrest Register between 2008 and 2009 in (a) 20 of 21 regions (n=6457) and in (b) 165 of 292 municipalities (n=3522) in Sweden, took part in the survey.

Results: The regional population density varied between 3 and 310 inhabitants per km(2) in 2009. In 2008-2009, the number of reported cardiac arrests varied between 13 and 52 per 100,000 inhabitants and year. Survival to 1 month varied between 2% and 14% during the same period in different regions. With regard to population density, based on municipalities, bystander CPR (p=0.04) as well as cardiac etiology (p=0.002) were more frequent in less populated areas. Ambulance response time was longer in less populated areas (p<0.0001). There was no significant association between population density and survival to 1 month after OHCA or incidence (adjusted for age and gender) of OHCA.

Conclusion: There was no significant association between population density and survival to 1 month after OHCA or incidence (adjusted for age and gender) of OHCA. However, bystander CPR, cardiac etiology and longer response times were more frequent in less populated areas.