Improving Regcognition of Stoke by Pre-Hospital Clinicians (Mimics)
Acute stroke services are currently centralised in Hyper Acute Stroke Units (HASUs) in Greater Manchester, meaning that when a patient suffers a suspected stroke, ambulance teams should transport the patient to the nearest HASU, and directly to the nearest hospital in all other cases. Despite this, a recent audit by the GM Stroke Operational Delivery Network (ODN) identified that around 48% of patients suspected strokes via the FAST test and taken to HASUs did not actually result in a stroke diagnosis. These false positive cases are referred to as stroke “mimics” whilst a false negative case was an incident in which a stroke was not recognised using the FAST test. The focus of this workstream was to improve the accurate recognition of stroke cases, reducing the number of stroke mimics and missed strokes.
Working alongside the Northwest Ambulance Service (NWAS) we first identified how many false positive (mimics) and false negatives (missed strokes) were currently occurring within Greater Manchester. FAST assessment notes were acquired from NWAS Patient Report Forms (PRFs) for analysis. We also introduced the Pre-Hospital Pathway Aid (PHPA) app developed by Greater Manchester Stroke Operational Delivery Network (GM ODN) into ambulance vehicles to help aid stroke recognition. The app was first piloted by 44 NWAS ambulance staff to determine its utility and plan for a wider rollout. A qualitative evaluation was also conducted via focus groups and interviews to explore the decision making of staff involved in the stroke pathway.
A total of 4,148 cases were included in the final cohort data analysis, the PRF diagnoses of whom revealed around 50% were actually experiencing a stroke whilst the other 50% were stroke mimics or false positives. During the piloting period for the PHPA app around 43% of interactions with the app were able to correctly identify a negative FAST test and ensure the appropriate transfer to hospital. As a result the app has been agreed for a full rollout with NWAS, with educational materials being disseminated to all staff in March 2019 ahead of rollout in April. Qualitative findings revealed that respondents were unaware of false positive stroke rates entering onto the stroke pathway. Pre-hospital clinicians receive limited feedback from jobs and this impedes their ability to learn from their experiences. Respondents reported difficulty in ruling out stroke in certain patient cohorts and difficulty in recognising differential diagnoses. They expressed a lack of confidence to rule out stroke in the pre-hospital setting. They also expressed greater concern for ‘missed strokes’.
Through analysis of the NWAS PRF data coupled with feedback from qualitative interviews and focus groups, there is a significant issue at present with false positive and false negative diagnosis of stroke in the pre-hospital setting. The successful piloting of the PHPA app has led to a wider rollout that will target the key issues highlighted by this workstream, to reduce the occurrence of incorrect diagnoses across Greater Manchester, and provide a dataset from which we can develop a model to enhance the current FAST test practices.