Elderly out-of-hospital cardiac arrest - a population wide analysis of prehospital registry data

Abstract

Introduction: With the highest life expectancy and one of the most aged population in the world, healthcare system in Hong Kong is now managing more elderly patients in out-of-hospital cardiac arrest (OHCA). This study aims to describe the epidemiology, outcomes, and predictors of survival from OHCA in geriatric population using territory-wide prehospital data. Methods: This retrospective cross-sectional study analysed consecutive OHCA patients aged 65 years or above, who were transferred by emergency ambulance service from 1st August 2012 to 31st July 2013. The primary outcome was 30-day survival. The secondary outcome was neurological recovery. Patients’ demographic data, site of arrest, presence of witness, initial cardiac rhythm, availability of bystander cardiopulmonary resuscitation (CPR) and defibrillation, resuscitation in emergency department, and prehospital time variables were described. Associations among independent variables and study outcomes were evaluated with univariate logistic regression. Survivors and non-survivors were compared using Mann-Whitney U and Chi-squared tests for continuous and categorical variables, respectively. Results: 3919 included elderly cases contributed to 76% of OHCA cases in all age groups during the study period. It corresponded to 416 arrests per 100,000 person-years, which outnumbered the overall population (72 arrests per 100,000 personyears). Most occurred in residential homes (50.3%), followed by nursing homes (38.4%). In-hospital resuscitation was not initiated in 64.4% cases. The 30-day survival rate was 1.5%. 0.8% achieved favourable neurological status on discharge, as defined by Cerebral Performance Category Scores of 1 or 2. The odds of 30-day survival dropped 11% with each year of age increase. Nursing home residents were less likely to survive (0.39%). Survival deteriorated with delays of activation of emergency medical service, ambulance arrival, and first defibrillation. If cardiac arrests were witnessed aboard ambulances, the survival odds were 10 times higher. Patients who received bystander CPR by police, and treatment with public access defibrillation (PAD) before ambulance arrival, outlived who did not by 13 times and 12 times, respectively. Initial ventricular fibrillation and pulseless ventricular tachycardia had better prognosis (Adjusted OR = 8.78, CI = 4.81 – 16.03, p < 0.001). Conclusion: The incidence of elderly OHCA was high and survival remained low. Chain of survival needs to be reinforced. Structured training for police officers, nursing home staff, home carers, and the public at large should be promulgated to shorten delays to CPR, defibrillation and ambulance service.