Background The requirement for guidance regarding ambulance crews pre-alerting patients into hospital emergency departments (ED) has been well established, but a clear guidance tool that supports a decision to pre-alert a receiving hospital is lacking.

Aims To investigate the impact of a new pre-alert tool on current alerting practice and evaluate its ability to take the place of a prehospital early warning system.

Methods Data were collected for a sample of patients brought by ambulance to the resuscitation area of Aberdeen Royal Infirmary ED over a 7-week period. Basic demographic information plus alert status and guidance prompt status was collected and compared with a pragmatic alert requirement. Analysis of ambulance crew alert decisions and the pre-alert guidance prompt advice was undertaken and compared.

Results Ambulance crew decisions to alert had a sensitivity of 72% (CI 62% to 80%), specificity of 50% (CI 27% to 73%), positive predictive value (PPV) of 90% and negative predictive value (NPV) of 22%. The pre-alert guidance alert prompt had a sensitivity of 99% (CI 94% to 100%), specificity of 64% (CI 39% to 84%), PPV of 95% and NPV of 90%. 28% of patients were under-alerted by ambulance crews, mostly medical patients presenting with chest pain.

Conclusions The pre-alert guidance tool shows face validity and superior ability to advise a pre-alert than ambulance crew decisions. It supplements a practitioners’ clinical decision-making and has been regarded as having a positive impact on ED triage and utilisation of resources. Further levels of validity are expected to be achieved with continued audit and ongoing use of this tool.