Hospital variability of out-of-hospital cardiac arrest survival

Background. Previous literature has identified patient and emergency medical services (EMS) system factors that are associated with survival of out-of-hospital cardiac arrest patients. Objective. To determine variability in rates of survival to discharge of resuscitated adult out-of-hospital cardiac arrest patients and to identify hospital-related factors associated with survival. Methods. This was a retrospective, observational study of all adult (21 years or older) out-of-hospital Utstein criteria cardiac-etiology arrests treated by Milwaukee County EMS during the period 1995-2005 and surviving to hospital intensive care unit admission. The primary outcome measure was survival to hospital discharge. Logistic regression analysis was used to compare the odds of survival between hospitals, patient factors, and hospital factors. Results. 1,702 patients at eight receiving hospitals were included in the study analyses. Hospital survival rates ranged from 29% to 42%. Patient and case factors associated with increased survival included younger age, male gender, nonwhite race, witnessed arrest in a public location, bystander cardiopulmonary resuscitation (CPR), a modest number of defibrillations, and initial cardiac rhythm of ventricular tachycardia. The only hospital characteristic correlated with survival was the number of beds per nurse. Patients admitted to a hospital with a ratio of beds to nurse less than 1.0 were over 1.5 times more likely to survive. Conclusions. Survival to discharge of resuscitated adult out-of-hospital cardiac arrest patients may vary by receiving hospital. A hospital's ratio of beds to nurse and several patient/case factors are correlated with survival. Further research is warranted to investigate how this may affect resuscitation care, EMS transport policy, and research design.