Background and aims. To evaluate survival until discharge from hospital in the case of patients resuscitated from bystanderwitnessed out-of-hospital sudden cardiac arrest (OHCA) in Estonia from 1999 to 2013 and to assess the factors of importance for survival in a group of patients admitted to hospital alive.
Methods. A prospective observational cohort study of out-of-hospital resuscitation attempts in Estonia from 01.01.1999 to 31.12.2013 was conducted according to the Utstein style. Survival until discharge from hospital was evaluated and compared for three 5-year study periods: I 1999–2003, II 2004–2008 and III 2009 and 2013. For the group of patients admitted to hospital alive, multiple logistic regression and stepwise regression were used to evaluate the factors associated with survival.
Results. Altogether, 38.8% (3335/8586) of the cardiac arrests had presumed cardiac etiology and were bystander-witnessed. Among them, 28.9% (965/3335) of the patients were admitted to hospital alive and 10.2% (341/3335) were discharged alive in terms of good cerebral performance categories (CPC 1, 2). Survival until discharge from hospital increased to 13.8% in study periood III compared to 9.4% (p = 0.0032) in study period I and compared to 7.9% (p < 0.0001) in study period II. Bystanders performed CPR in 33.6% of cases in study period III versus 25.6% (p < 0.0001) in study period I and versus 26.2% (p = 0.0004) in study period II.
For the group of patients admitted to hospital, the median response time interval in the survival group was 6 min compared with 7 min for patients who died in hospital (p < 0.0001) and median resuscitation time was 11 min compared with 21 min (p < 0.0001), respectively. In study period III the chance of survival improved in the subgroup of patients who underwent therapeutic hypothermia (OR = 1.43; 95% CI 0.84–2.44). Stepwise logistic regressioon revealed that the chance to survive in the group of hospitalized patients was higher in study period III (OR = 2.73; 95% CI 1.80–4.13) among the patients who received chest compression-only bystander CPR (OR = 1.89; CI 1.23–2.88) and among the patients in the subgroup of ventricular tachycardia or ventricular fibrillation (OR = 2.69; 95% CI 4.25–6.37). Compared with the patients under the age of 40 years, the chance to survive was significantly lower among the patients aged between 40-60 years (OR = 0.34; 95% CI 0.16–0.73) and over 60 years (OR = 0.17; 95% CI 0.08–0.37), as well as for the subgroups with the ambulance response time interval >10 min (OR 0.37; 95% CI 0.21–0.64) and with the resuscitation time interval between 10-20 min (OR = 0.32; 95% CI 0.21–0.47) and more than 20 min (OR = 0.09; 95% CI 0.005–0.16). After hospital admission there were no significant differences in the survival of patients depending on the prehospital treatment of OHCA provided by the physician/nurse or the nurse/nurse ambulance crew.
Conclusions. In Estonia, during the whole study period from 1999 to 2013, the survival of patients resuscitated from bystanderwitnessed OHCA increased in the third study period (2009–2013). High availability of emergency medical service, early defibrillation and early bystander CPR are very important factors associated with survival after OHCA.