Award-winning data linkage project improves bystander CPR rates and survival in Scotland

This was one of many improvements highlighted in the latest findings from the OHCA Data Linkage Project, which also showed that, for the first time, more than one person in ten suffering a cardiac arrest outside of hospital is surviving and leaving hospital.

When the Scottish Government launched the OHCA Strategy in 2015 to ensure Scotland became a leader in OHCA survival, only around one in 20 people survived to hospital discharge. The OHCA Data Linkage Project was central to this strategy and set out to improve data collection and reporting on OHCA by tracking patient outcomes and measuring the impact of the strategy. 

There is a high level of international consensus about the steps required to improve patient outcomes following an OHCA. The first of these is to build a mechanism to measure current system performance, identify areas for improvement and track progress. Interventions can then be developed and tested using evidence to inform improvements in real time.

However, this is not a straightforward process as the system delivering care to victims of OHCA spans multiple agencies. Assembling meaningful data requires the synthesis of information from a range of data sources. In order to know how many patients fall victim to OHCA each year, the details of emergency calls to the Scottish 

Ambulance Service (SAS) is first required. This gives the number of incidents where Ambulance Service personnel attempted resuscitation for OHCA. As Ambulance Service data collection stops when the patient is delivered to hospital, in order to calculate the proportion of OHCA survivors, information is required about in-hospital care. 

This is accessible via a patient’s Community Health Index (CHI) number. The CHI number uniquely identifies everyone registered with the healthcare system in Scotland. 

The linkage of Ambulance Service cases with the patient's CHI number transforms 'incidents' into CHI-linked patient records.

Prior to linking the data, a number of permissions had to be secured before it could be shared and linked. The use of the data is also restricted to a highly controlled 'safe haven' environment in order to preserve patient confidentiality. The linked dataset was stored in the NHS National Services Scotland (NSS) safe haven environment and was accessible to authorised researchers only after compliance with specific information governance, data stewardship and system security requirements.

To-date, the project has brought together and linked eight different complex data sources held by national organisations. The linked dataset has enabled researchers to discover more information about the demographics of people having an OHCA, the number of bystander CPR’s attempted, and ultimately whether patients survived beyond 30 days.

Specifically, the latest report found that:

• Bystander CPR rates increased to 64.0% in 2018/19 compared with 55.5% in 2017/18
• Survival at 30 days has increased to 10.2% in 2018/19 compared to 8.3% from the previous year
• CPR familiarisation through the Save a Life for Scotland Partnership continues to increase yearly since its inception in October 2015
• Deprivation continues to have a significant effect on the likelihood of receiving bystander CPR. Those in the most deprived areas are 12.6% less likely to receive bystander CPR compared to those in the least deprived areas
• There was a trend towards increased use of public access defibrillators by bystanders.

Roger Halliday, Chief Statistician for the Scottish Government, said "The recent award win for the OHCA data linkage project is testament to the significant impact it has already had in improving people’s lives. Scotland’s innovative and collaborative approach to using public sector data in an ethical way is helping to transform our public services to ultimately save lives. 

"We want to help researchers carry out more award-winning projects like this one, so we’re setting up Research Data Scotland. This will provide access to data that will support answering both policy and research questions that are broadly aligned to Scotland’s National Outcomes. This is being made possible through the UK wide investment into Administrative Data Research (ADR UK) by the Economic and Social Research Council."

More information about the OHCA data linkage project can be found on the Scottish Government website.