Perspective:

This is a large population-based epidemiological study of bystander resuscitation and survival following out-of-hospital cardiac arrest. The study is well-done and uses a fairly rigorous data source to capture a large number of patients with these events over a long study period (although some key variables did exhibit high rates of missing values). What I really enjoyed about this article though is the overall balance with which it was written. The authors recognize that this is an ecological analysis; thus, they have been careful not to describe associations they have noted over time between bystander resuscitation and survival as causal. The authors also point out that they are limited in discussing nonmortality outcomes (such as cognitive performance) and have limited data on advanced care that was used (e.g., hypothermia or coronary revascularization). That said, the article is supportive of national efforts in the United States and elsewhere to improve bystander resuscitation, and complements nicely work published last year from the CARES registry (see Sasson C, et al. N Engl J Med 2012). In that provocative paper, bystander resuscitation occurred in approximately 29% of patients with out-of-hospital cardiac arrest from 29 cities across the United States. The odds of undergoing resuscitation varied substantially based on socioeconomic factors and suggest opportunities to target these areas for improvement. This is urgently needed, given the continued poor survival following these events (even in Denmark).