1. Out-of-Hospital Cardiac Arrest Outcomes Project Epidemiology Report

2. National Out of Hospital Cardiac Arrest Outcomes Project
The OHCAO Project is supported by the Association of Ambulance Chief Executives and the National Ambulance Service Medical Directors, and is funded by the British Heart Foundation and Resuscitation Council (UK). Members of the OHCAO team are also supported by the National Institute for Health Research.

3. OHCA Survival in England
It is estimated that about 50,000 out-of-hospital cardiac arrests (OHCA) occur each year in England. Resuscitation may be inappropriate (due to a variety of reasons such as co-morbidity) and so attempted resuscitation by ambulance services occurs in less than 50% of cases. However, there is significant variability between ambulance services in the incidence of OHCAs, in rates of successful initial resuscitation (13-27%) and survival to hospital discharge (2-12%) following an OHCA. The variability persists even after adjustment for the Utstein comparator group (cardiac arrest of presumed cardiac origin, where the arrest was bystander witnessed and the initial rhythm was ventricular fibrillation or ventricular tachycardia).
Perkins & Cooke, 2011

4. “save 1000 lives a year”
If survival rates were increased from the overall average (7%) to that of the best reported (12%), it is estimated that an additional 1,000 lives could be saved each year.

5. The strategy documents highlight the importance of the Chain of Survival, but it is important to note that “You Can’t Improve What You Don’t Measure”.

6. OHCA National Framework
The recent national framework to improve care of people with OHCA in England “Resuscitation to Recovery” highlighted a number of aims to improve survival one of which was that “Data should be submitted to the national OHCAO Registry so that performance and progress towards improved survival rates can be monitored and unwarranted variation can be addressed; appropriate local resources must be allocated for these audit purposes”.

7. Perkins GD, Jacobs IJ, Nadkarni VM, et al 2015
The OHCAO registry is structured and maintained in accordance with the Utstein guideline for resuscitation registries and outlined in the ILCOR Consensus Statement, the Utstein elements being grouped into 5 domains:
System
Dispatch
Patient
Process
Outcome
Perkins GD, Jacobs IJ, Nadkarni VM, et al 2015

8. Details of the OHCAO registry have been summarized previously and in 2015 received data from 10 of the 11 ambulance services in England.
Talks with Wales, Scotland and Northern Ireland are progressing to receive their data also.

9. 2015 Annual OHCA Epidemiology and Outcomes

10. Data completeness of key cardiac arrest variables
Concentrating on the key variables that follow the chain of survival we can see where variation in data quality presents, allowing the OHCAO team to focus on improvement plans with each site. During the data import process an assessment of the quality of the key variables is made, and the proportion of cases that are ‘valid’, ‘out-of-range’ or ‘missing’ during the data import process of these key variables. A value is ’missing’ if nothing has been entered into a field. A ’valid’ and ’out-of-range’ value is variable specific and depends on the type of variable, all possible entries being agreed with on a service-by-service basis .
This figure summarizes the proportion of each of the key core variables that contains a ‘valid’ entry, i.e. no missing or out-of-range data. The figure show that for 2015 the data quality from all ambulance service was good. However, there was considerable variation for some of the variables between the services.

11. Number of resuscitation attempted cases
This figure shows the number of OHCAs where resuscitation was attempted, submitted to the OHCAO registry in The total number of eligible cases in 2015 was 28,914, which is less than a 1% increase of 2014’s figure of 28,729. There is large variation in number supplied, the overall service average was 2,891.
The difference in numbers in services 4, 5 and 10 are because the data was incomplete for 3 months in 2014 (services 5 and 10) and 2015 (service 4).

12. Incidence of OHCAs where resuscitation was attempted
Adjusting for the size of the population resulted in an overall incidence of 53.4 OHCA cases per 100,000 population in 2015 (2014: 53.0/100,000). There was a large variation between the services, from 32.0/100,000 to 68.3/100,000. These variations can be due to the characteristics of the population that each ambulance trust serve.
These variations can be due to the characteristics of the population that each ambulance trust serve. Studies have shown significant geographical variation in OHCA incidence; and that age structure (especially the proportion of the population aged over 65), the gender ratio, ethnic make-up, the proportion of the population classed as deprived, the smoking prevalence, and education level were all significant predictors of OHCA incidence*.
* Straney, L.D., et al. (2016), 'Are sociodemographic characteristics associated with spatial variation in the incidence of OHCA and bystander CPR rates? A population-based observational study in Victoria, Australia.', BMJ Open, 6, e

13. Age/Sex distribution of EMS treated OHCAs
Morbidity and mortality rates for cardiovascular disease are known to differ significantly between men and women, and increase with age. The age and sex distribution of OHCAO cases for 2015 is shown, the numbers increase exponentially in both sexes after age 0-4y. The total number of male EMS resuscitation attempts was 16,523 compared to 9,581 female, giving a national ratio of 1.72:1.

14. Age/Sex incidence of EMS treated OHCAs
Similar to the number of OHCAs, OHCA incidence also increases exponentially with age in both sexes.
Further investigation is planned to analyse the discrepancy of cardiac arrest calls between males and females; one hypothesis is that the underlying diseases leading to death are different between men and women, and the underlying disease process naturally has a different likelihood of generating a cardiac arrest call. Annual statistics published by the ONS indicate the top three causes of death for males are ischaemic heart disease (IHD), dementia and Alzheimer’s disease (DAD) and lung cancer; for women the top three are DAD, IHD and cerebrovascular disease. Prostate cancer and diseases of the liver are in the top 10 for men whereas breast cancer and diseases of the urinary system are in the top 10 for women.
Also a patient who experiences VF after a myocardial infarction is very different from the patient with sepsis who loses mechanical cardiac function from progressive acidosis and pulseless electrical activity (PEA). However, one generally considers these patients as having the same clinical state regardless of the underlying disease process.

15. Location of OHCAs in the OHCAO registry
The location, and neighbourhood characteristics, where an OHCA occurs significantly impacts on the chances of survival for a patient. According to the British Heart Foundation approximately 80% of OHCAs occur at home and 20% in public places, away from onlookers who might have been able to help and where defibrillators are not usually available. It has been estimated that the chances of survival from an OHCA is over three-times greater if the event occurred in a public place compared to the home.
This figure indicates that from information sent to the registry we were able to determine that just over 50% of cases occurred inside the home. The location (home and non-home) was defined by comparing the postcode of the cardiac arrest event and patient’s home postcode. If the postcodes were identical, the location was defined as “Home”. If postcodes were different, the location was defined as “Non-home”. For patients with incomplete home/event postcode data, the location was included in the non-home category.

16. Initial aetiology of resuscitation attempted cardiac arrests
This figure gives information on the initial aetiology of OHCA cases in the registry. If the entry was entered as “Unknown” or “Unobtainable”, then according to the Utstein criteria it was re-classified as “Cardiac”. As expected the significant majority of cases were of cardiac origin, 58.4%, which was slightly below the corresponding figure in 2014 of 60.9%.

17. Witness status of OHCAs in registry
Research has indicated that if an OHCA is witnessed by a bystander or by EMS personnel the likelihood of the patient surviving to hospital handover and to hospital discharge increases. It is estimated that if an OHCA was witnessed by a bystander the odds of survival were four-times greater than in a case that was not witnessed. If an OHCA was witnessed by EMS personnel then the odds of survival were over seven-times greater*.
In the registry about 45% of OHCAs were witnessed by a bystander and about 13% witnessed by the EMS. However, about 37% were not witnessed at all. Corresponding figures for 2014 were 36.2%, 12.9% and 36.2%, respectively.
* Rea, T.D., et al. (2010), 'Predicting survival after out-of-hospital cardiac arrest: Role of the Utstein data elements.', Annals of Emergency Medicine, 55 (3),
Sasson, C., et al. (2010), 'Predictors of survival from out-of-hospital cardiac arrest: A systematic review and meta-analysis.', Circulation: Cardiovascular Quality and Outcomes, 3 (1),
NB: Bystander category contains records where ambulance service indicated “Layperson” or “Yes”

18. Bystander CPR rate in non-EMS witnessed cardiac arrests
Bystander action in public places, including bystander CPR (BCPR), is a key factor influencing overall survival following OHCA. Early CPR and defibrillation can improve OHCA outcomes if more widely adopted, and early CPR by a bystander has been shown to increase the odds of survival by up to five-times*.
Previous studies in the UK have shown variable bystander CPR rates around the country: 29.4% in Nottinghamshire (Soo et al. 2001), 43.2% in Scotland (Ghose et al. 2010), 31.9% in London (Shah et al. 2010) and 19.6% in Newcastle (Moncur et al. 2016). These figures are lower than in other countries with similar demographics: 73% in Norway (Lindner et al. 2011), 66% in Seattle (Nichol et al. 2008), >60% in North Holland (Grasner et al. 2006), and 71% in Denmark (Nielsen et al. 2014). However, we must be careful when making direct comparisons because there is variability in how bystander rates are calculated. We have calculated rates in non-EMS witnessed OHCAs, as did Ghose and Moncur, whereas Soo and Shah included all cases. In addition, the age of cases investigated has a significant impact on whether they receive bystander CPR or not, and these differ considerably between the studies.
The proportion of non-EMS witnessed OHCAs, i.e. bystander-witnessed, that received CPR from a bystander varies between the different services, with an overall average of 56.6% (2014: 55.2%).
* Rea, T.D., et al. (2010), 'Predicting survival after out-of-hospital cardiac arrest: Role of the Utstein data elements.', Annals of Emergency Medicine, 55 (3),
Sasson, C., et al. (2010), 'Predictors of survival from out-of-hospital cardiac arrest: A systematic review and meta-analysis.', Circulation: Cardiovascular Quality and Outcomes, 3 (1),
Berdowski, J., et al. (2010), 'Global incidences of out-of-hospital cardiac arrest and survival rates: Systematic review of 67 prospective studies.', Resuscitation, 81,
Ghose, R., et al. (2010), 'Bystander CPR in south east Scotland increases over 16 years', Resuscitation, 81 (11),
Lindner, T.W., et al. (2011), 'Good outcome in every fourth resuscitation attempt is achievable - An Utstein template report from the Stavanger region.', Resuscitation, 82,
Moncur, L., et al. (2016), 'Does the level of socioeconomic deprivation at the location of cardiac arrest in an English region influence the likelihood of receiving bystander-initiated cardiopulmonary resuscitation?', Emergency Medical Journal, 33 (1),
Nielsen, A.M., et al. (2014), 'Persisting effect of community approaches to resuscitation.', Resuscitation, 85,
Nichol, G., et al. (2008), 'Regional variation in out-of-hospital cardiac arrest incidence and outcome.', Journal of the American Medical Association, 300 (12),
Shah, A.S., et al. (2010), 'Out-of-hospital cardiac arrest in South Asian and white populations in London: database evaluation of characteristics and outcome.', Heart, 96 (1),
Soo, L.H., et al. (2001), 'Geographical distribution of cardiac arrest in Nottinghamshire.', Resuscitation, 48,
Soo, L.H., et al. (1999), 'Resuscitation from out-of-hospital cardiac arrest: is survival dependent on who is available at the scene?', Heart, 81 (1),
NB: Best performing communities are those from rest of world, e.g. Seattle, North Holland, Norway, Denmark, etc.

19. Arrival time of EMS to OHCA events
Studies have shown that the chances of survival decrease significantly the longer it takes the EMS to arrive at the location of the OHCA. Ambulance response times (ART) have long been known to be independently associated with defibrillation and survival in OHCAs, and the recommended response time is 8-minutes. In the UK, a study of the effect of reducing ART observed that a reduction in the 90th centile ART from 15 to 8-minutes resulted in an 8% increase in the number of potential survivors. Reducing ARTs to 5-minutes was observed to almost double the survival rate for cardiac arrests not witnessed by ambulance crews.
The figure presents details of the arrival time of EMS personal to an OHCA. For any cardiac arrest that was first witnessed by EMS personnel the arrival time was changed to 0 minutes. About 50% of all non-EMS witnessed OHCAs were reached in under 8-minutes. After 8-minutes there was an exponential decline in the proportion of cases with arrival time, however, approximately 11% of cases were still not reached after 19-minutes. The reason for the latter is unknown. These could include cases where cardiac arrest was not recognized at the time of the emergency call leading to a lower response category. It is also possible that it includes patients who sustained a cardiac arrest after the initial 999 call was made.
* Abrams, H.C., et al. (2013), 'A composite model of survival from out-of-hospital cardiac arrest using the Cardiac Arrest Registry to Enhance Survival (CARES)', Resuscitation, 84,
O'Keeffe, C., et al. (2010), 'Role of ambulance response times in the survival of patients with out-of-hospital cardiac arrest.', Emergency Medical Journal, 28 (8),
Ono, Y., et al. (2016), 'The response time threshold for predicting favourable neurological outcomes in patients with bystander-witnessed out-of-hospital cardiac arrest.', Resuscitation, 107,
Pell, J.P., et al. (2001), 'Effect of reducing ambulance response times on deaths from out of hospital cardiac arrest: cohort study.', British Medical Journal, 322,

20. Initial rhythm of EMS treated OHCA events
Heart rhythms associated with cardiac arrest are divided into two groups: shockable rhythms (ventricular fibrillation or pulseless ventricular tachycardia (VF/VT)) and non-shockable rhythms (asystole, pulseless electrical activity, and bradycardia). OHCA cases found in VF/VT have a significantly increased odds of surviving. It is reported that a case found in VF/VT was 2.9 to 20.6 times more likely of surviving, and that if a patient has a shockable rhythm they had an increased chance of achieving ROSC, surviving to hospital discharge and have a favourable neurological outcome*. OHCA cases found in a shockable rhythm (VF/VT) have a significantly increased odds of surviving.
Data in the OHCAO registry indicate that the first monitored rhythm in approximately 20% of OHCAs. About 48% were in asystole and 20% in PEA.
* Mader, T.J., et al. (2012), 'Out-of-hospital cardiac arrest outcomes stratified by rhythm analysis.', Resuscitation, 83,
Sasson, C., et al. (2010), 'Predictors of survival from out-of-hospital cardiac arrest: A systematic review and meta-analysis.', Circulation: Cardiovascular Quality and Outcomes, 3 (1),
NB: Unknown category include “AED Non-Shockable”

21. Rate of ROSC at hospital handover
According to the OHCAO registry there were 28,914 patients in 2015 where resuscitation was commenced or continued by ambulance staff. Data from two services (4 and 10) could not be included in the analysis of ROSC because they were unable to supply this information, resulting in a total of 23,213 OHCAs. Of these, 27.6% (n=6,950) had achieved ROSC at hospital arrival. There was large variation between the services.

22. Survival to hospital discharge in all EMS treated OHCAs
Considering all patients in the OHCAO registry, 7.8% (n=1,962) of all OHCA cases survived to hospital discharge (Figure 17). There is some variation between the services. Services 4 and 10 could not supply data for survival to discharge.

23. Survival from hospital handover to hospital discharge
Following all those patients that achieved ROSC at hospital arrival (n=6,950), 26.1% (n=1,816) survived to hospital discharge.

24. OHCAO Recommendations
The OHCAO team recommend a series of points that could be considered to improve the quality of information within the OHCAO registry. We are also proposing to work closer with each ambulance service with the aim of improving the completeness of information provided and therefore the quality of information that is stored in the registry.
· Review a selection of cases where cardiac arrest was not recognised at the time of the initial call. Establish any common themes and share with call operators.
· Are call operators familiar with the combination of unconsciousness and absence of normal breathing being the commonest signs of cardiac arrest?
· Review a selection of cases where cardiac arrest was identified during the call.
· Was telephone CPR instructions offered?
· Can you reduce the time from call to first compression?
· Did you contribute to European Restart a Heart day? Is there scope to increase contribution next year?
· Do you provide feedback on quality of CPR to crews?
· Have you mapped PADs in your community?
· Do you have a system which automatically alerts the call operator to the nearest PAD?
· What proportion of cardiac arrests were attended by a first responder?
Is there scope to increase the pool of first responders? (e.g. Police, GoodSam volunteers)
· What proportion of patients had an ECG after ROSC?
· Were patients with STEMI after ROSC taken to a PCI centre?
Do you provide feedback to call operators and crews on patient outcomes?