TRIM: What Triage Model Is Safest And Most Effective For The Management Of 999 Callers With Suspected COVID-19? A Linked Outcome Study

999 emergency ambulance calls related to COVID-19 have increased enormously at various points during the coronavirus pandemic. On some occasions, the volume of calls has tripled. Ambulance services cannot send an ambulance to every caller within a reasonable timeframe and not every patient with suspected COVID-19 can be taken to hospital. If the right patients are not sent an ambulance or are left at home, they could suffer harm or even death. But, if every patient is taken to hospital, Emergency Department and inpatient services may be overwhelmed and unable to cope. Ambulance services use different models to sort out - or triage - callers, but little is known about what model of triage works most safely and effectively during a pandemic.

We will compare outcomes for patients treated using different triage models employed by ambulance services in call centres and on scene during the 2020 pandemic. We will retrieve these outcomes from NHS datasets, including data on deaths; hospital and ITU admissions; Emergency Department attendances; and COVID-19 diagnosis.

We will interview health service staff to understand experiences and concerns.

We will deliver findings quickly to help implement the best model for sorting and treating 999 callers with suspected COVID-19 symptoms.

The COVID-19 epidemic in the UK has caused surges in 999 calls from people concerned about possible coronavirus symptoms including fever and shortness of breath. The London Ambulance Service, for instance, has, at times, received three times its usual number of 999 calls each day for a sustained period.

The emergency ambulance service has to triage calls to decide, firstly, whether to dispatch a vehicle to attend a caller for face to face assessment, and, if attended, whether to convey the patient to hospital. This triage is key to identifying patients who need to be treated in hospital. Undertriage will result in patient harm, in this case, avoidable deaths. Overtriage will result in unnecessary conveyance to the Emergency Department, exposing patients to risk of infection, diverting resources from those in need and overburdening already pressurised services.

Different models of triage are being used by services across the UK, reflecting different: priority dispatch systems (AMPDS, NHS Pathways); models of clinical advice in the ambulance call centre (paramedics, nurses, medics including GPs); response options (Emergency Medical Technician/paramedic/advanced paramedic staff; patient carrying/non-patient carrying vehicle); protocols for on scene triage to make conveyance decisions; and options for referral or call back.

The lack of evidence about what model of triage works best for patients and the NHS in a pandemic situation such as COVID-19 will be filled by this linked outcome study across England, Wales and Scotland.