Fig. 4.

Crude and adjusted association of population density and bystander CPR, Reference group = Low population density (<300/km²). Logistic regression analysis for the association of population density and bystander CPR showing the crude and the adjusted odds for bystander CPR in groups of population density: medium (300–1499/km²), high (1500–2999/km²) and very high (>3000/km²) in reference to low (<300/km²). The adjusted analyses were adjusted for age, gender, calendar year and comorbidities from baseline Table 1. Odds ratio >1.00 indicates that patients in areas of medium, high and very high population densities in reference to low are positively associated with bystander CPR. CPR, cardiopulmonary resuscitation; OHCA, out-of-hospital cardiac arrest; OR, odds ratio. CPR, cardiopulmonary resuscitation; EMS, emergency medical service; OHCA, out-of-hospital cardiac arrest; OR, odds ratio.