Paramedic identification of stroke: community validation of the melbourne ambulance stroke screen

Background: Paramedics require an effective prehospital tool to eliminate stroke mimics and to assist in the identification of suitable candidates for thrombolytic therapy. The Faster Access to Stroke Therapies study combined two validated stroke assessment tools (the Los Angeles Prehospital Stroke Screen, LAPSS, and the Cincinnati Prehospital Stroke Scale, CPSS) to form the Melbourne Ambulance Stroke Screen (MASS), and performed an in-field validation by Australian paramedics.

Methods: Over a 12-month period, 18 paramedics participated in the Faster Access to Stroke Therapies study and prospectively collected data contained in the MASS on all stroke dispatches, and for other patients with a focal neurological deficit. Sensitivity and specificity analysis of the LAPSS, CPSS and MASS was calculated and equivalence analysis performed.

Results: Paramedics completed 100 MASS assessments for 73 (73%) stroke/transient ischemic attack patients and 27 (27%) stroke mimics. The sensitivity of the MASS (90%, 95% CI: 81-96%) showed statistical equivalence to the sensitivity of the CPSS (95%, p = 0.45) and superiority to the LAPSS (78%, p = 0.008). The specificity of the MASS (74%, 95% CI: 53-88%) was equivalent to that of the LAPSS (85%, p = 0.25) and superior to the CPSS (54%, p = 0.007). All patients misidentified by the MASS (7 strokes, 7 mimics) were ineligible for thrombolytic therapy.

Conclusion: The MASS is simple to use, with accurate prehospital identification of stroke. It distinguishes stroke mimics, with good recognition of suitable patients for thrombolytic therapy.