Purines for Rapid Identifcation of Stroke MImics (PRISM)


Stroke is the 2nd leading cause of death worldwide and the commonest cause of adult disability in the western world. It is responsible for a huge health and social care burden which exceeds heart disease, including £5.5bn/year for treatment (5% of the NHS budget) and £5bn/year economic impact for care costs and lost earnings. Powerful evidence exists that even small improvements in the accuracy of diagnosis and the speed of treatment produce large gains for population health and greatly reduced care costs. The impact is greatest when stroke is caused by an arterial blockage (85%), as the chance of a faster, better recovery is directly related to how quickly patients are treated with a clot busting drug (thrombolysis within 4.5 hours) or surgical clot removal (thrombectomy within 6 hours for large arteries). Even when unsuitable for one of these treatments, all patients benefit from admission to a centralised specialist Hyperacute Stroke Unit (HASU), which often involves bypassing a local A&E. Ambulance services are responsible for the initial recognition of symptoms that might be due to stroke. However, it is a challenging condition for non-specialists to diagnose correctly in the first few critical hours, and a number of other conditions have the same symptoms as stroke, resulting in “mimics” patients entering the stroke treatment pathway. As a result, there is a high degree of misdiagnosis: 30% of stroke patients go unrecognised in A&E; 50% of suspected stroke patients identified by paramedics turn out to have mimic conditionss; and up to 17% of patients receiving thrombolysis (an expensive and potentially hazardous treatment) have not had a stroke. Mimic conditionss are also a major burden on limited resources; around 13,500 mimic patientss annually are treated by NHS HASUs at an additional cost of £31m compared to a standard hospital bed. Accurate identification of stroke and mimic patients in ambulances and A&E departments would lead to improved patient outcomes and better use of limited specialist resources. Sarissa Biomedical is working with researchers and NHS services to develop a simple Point of Care Diagnostic blood test (SMARTChip) which measures blood purine levels. Studies in hospital have shown that these are an extremely early indicator of stroke. As the majority of referrals to HASU are via ambulance, developing SMARTChip for paramedic use would assist in the correct diganosis of stroke and significantly reduce the number of patients being inappropriately directed to HASUs. This would ensure that specialist resources are reserved for stroke and enable mimics patients to be assessed in a more appropriate local setting. The purine levels correlate with stroke severity and rapidly provides clinicians with additional information to optimise treatment decisions (i.e. to follow a thrombolysis and/or thrombectomy pathway). Phase 1 of this project confirmed that SMARTChip would be valued by clinicians and could be deployed in NHS services with a projected saving of over £25 million annually. Phase 2 will seek regulatory approval and commissioning support for routine clinical use by generating evidence of patient and service benefits, operational feasibility and positive economic impact.

Lead Participant

Project Cost

Grant Offer

Northumbria Healthcare NHS Foundation Trust, Coventry £1,998,604 £ 1,998,604


10 25 50