Ambulance arrival before OHCA maximizes survival
MedWire News: Concentrating resources on reducing ambulance response times to patients at immediate risk for going into out-of-hospital cardiac arrest (OHCA) could save lives, say UK researchers.
The arrival of an ambulance crew before the arrest greatly improved patients' chances of survival, they report. But although reduced response times improved survival even for patients already in arrest, this came at a huge financial cost.
Overall, just 2.6% of patients with OHCA survived to hospital discharge, based on 30 survivors from 1161 patients reported as unconscious, not breathing, or with acute chest pain who were attended by the ambulance services over a 5-year period in England.
If the patient was in arrest by the time the ambulance crew arrived (n=1054), their survival chances were just 1.8%, the researchers report in the Emergency Medical Journal. But if an ambulance crew was with them by the time they had OHCA, the patients' survival chances were greatly improved, at 13.8%.
In line with previous studies, the team found that, for patients already in arrest at ambulance arrival, shorter response times increased their likelihood of survival. For those found in ventricular fibrillation (n=415), a response time of 6 minutes or less resulted in a survival rate of more than 5%. If these patients also received cardiopulmonary resuscitation from a bystander, their survival rate rose further, to 14.5%.
On multivariate analysis, each 1-minute reduction in response time improved patients' chances of survival by 24.0%, and being in ventricular fibrillation improved their survival chances 5.57-fold.
Conversely, each 1-year increase in age reduced the likelihood of patients surviving by 3%.
Colin O'Keeffe (University of Sheffield) and colleagues calculate that each OHCA survivor would achieve an average of 3.72 quality-adjusted life years (QALYs), but that this would come at a cost of £1.68 (US $2.76, €1.93) million per year to a typical English ambulance service and £54 (US $88.6, €62.1) million per year across England and Wales.
This cost is beyond what the UK National Health Service can currently pay per QALY, say the researchers, suggesting that "reducing ambulance response times across the board may not represent a cost-effective policy unless there are substantial additional benefits."
But they add: "Overall it is possible that rapid response to patients in immediate risk of arrest may be at least as beneficial as rapid response to those who have arrested.
"Other approaches to improving survival from cardiac arrest that may be more cost-effective than reducing response times include more emphasis on the quality of care provided by paramedics at the scene, greater public access to defibrillators, public training in basic life support, and secondary prevention in patients with established cardiovascular disease to prevent OHCA."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Eleanor McDermid