Effect of online medical control on prehospital Code Stroke triage.

OBJECTIVE Prehospital Code Stroke triage has the potential to overwhelm stroke centres by falsely identifying patients as eligible for fibrinolysis. We sought to determine whether online medical control (whereby paramedics contact the medical control physician before a Code Stroke triage is assigned) reduced the proportion of false-positive Code Stroke patients. METHODS Following the introduction of a protocol for prehospital Code Stroke triage in an urban centre, online medical control alternated with off-line medical control (whereby paramedics implement Code Stroke triage independently) over 4 discreet intervals. We reviewed data for patients triaged to 3 regional stroke centres to compare the proportion of false-positive Code Stroke patients during online versus off-line medical control. We predefined false positives as patients triaged as Code Stroke who had symptoms discovered on awakening, were last seen in their usual state of health greater than 2 hours before assessment or had a final diagnosis other than stroke. RESULTS The proportion of false positives was lower during online medical control (31% v. 42%, p = 0.003). This was explained by a lower proportion of patients whose symptoms were discovered on awakening (8% v. 14%, p < 0.001) and who were last seen in their usual state of health greater than 2 hours before assessment (22% v. 32%, p = 0.005). A final diagnosis of stroke was similar in the 2 groups (77% v. 79%, p = 0.39), as was the proportion of patients receiving fibrinolysis (35% v. 33%, p = 0.72). Eighteen percent of patients were denied Code Stroke triage during online control, most commonly because of the time of symptom onset. CONCLUSION Online medical control is associated with a reduced proportion of false-positive Code Stroke triage.