Aintree University Hospital NHS Foundation Trust

How CRAB is used as an early warning system and provides board level assurance on mortality and morbidity


Aintree University Hospital has dedicated assessment services including an Acute Medicine Unit, Ambulatory Emergency Care Unit, Acute Frailty Unit and a Surgical Assessment Unit. In addition, Aintree provides specialist services including major trauma, complex obesity care, head and neck surgery, upper GI cancer, hepatobilliary, endocrine services, respiratory medicine, rheumatology, ophthalmology and alcohol services.

Consultant Simon Scott explains how he first came across CRAB when the trust’s clinical director arranged a presentation to show how it could be used to make mortality and morbidity comparisons. “Most of us in the room didn’t realise this data was available and we hadn’t really been engaged, so I agreed to champion the initiative to get more of us using it.”

Quality assurance, appraisal and revalidation

“As surgeons we can see the benefit of using data, but it is particularly important to monitor mortality and morbidity from an audit point of view, but also for quality assurance and appraisal,” he says. The starting point was for me to show as many colleagues as possible and work with them on improving the quality of the data. In some cases patients were being incorrectly attributed to surgeons. “My own take on this is that as soon as colleagues were aware the data is being collected, they began to think about what they were doing and as a result we were more likely to see an improvement,” he says.

A monthly review group was set up and reports were also prepared for executive team meetings which involved the medical director. The aim was to use it as an early warning system to highlight potential problems within departments or with individual surgeons.

“If everything is going well the CEO does not need to get involved, but we keep a much closer eye on trends. If we see trends we think warrant further investigation we will run off further reports to identify what might be causing it.”

Complication rates

“Complication rates are reviewed centrally by NHS England and if something is picked up we can refer to CRAB, which gives us a very detailed picture of what has been happening,” says Simon. He uses the example of a patient who is referred from a tertiary centre and attends with a leak. This sort of detail is picked up by CRAB whereas previously it would have been counted as a complication.

Benefits for patients

Simon also believes there are benefits for patients because CRAB allows the trust to challenge individual practice where it is having a detrimental impact on patient care. “If we see a surgeon with a higher than average risk of complication we can write to the surgeon and ask them to explain the trend. We are also much more likely to find out when a patient has been operated on unnecessarily. “By using CRAB Medical you can look at all admissions (including patients admitted who didn’t have an operation) so you can see whether a particular surgeon is being under or indeed over cautious,” says Simon.


  • Clinical engagement has helped the trust improve its assessment of risk
  • CRAB is trusted by the medical director to present a true picture of surgical practice
  • The trust is able to challenge individual practice where the data suggests areas of improvement can be made
  • The trust has greater vigilance and oversight in key outcome measures

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