Effect of prehospital notification on acute stroke care: a multicenter study

Data was collected from patients treated at nine acute care hospitals in Taipei City with the cooperation of the local EMS system. These participating hospitals receive about 55 % of the 80,000 to 90,000 patients served by the EMS system in Taipei City annually, and these hospitals routinely provide thrombolytic therapy for stroke patients. The Fire Department of Taipei City is responsible for the EMS system. In the catchment area of the participating hospitals, the EMS system is a two-tier system consisting of 41 basic life support units and 4 advanced life support (ALS) units. In these units, there were 591 emergency medical technicians (EMTs) qualified as EMT-Intermediate who had received 280 h of training, and 84 paramedics who had completed 1280 h of training during the study period. No strict rule was implemented to ask the dispatcher to dispatch an ALS unit for patients with a suspected stroke, except when the patients were identified as having a critical condition. Most patients suspected as stroke were served by EMT-Intermediates. A close collaboration between hospitals and the EMS system when providing stroke patient care had not been well established in Taipei until recent years. Since 2011, the EMS system have used new prenotification criteria, which include: (1) a positive finding on the Cincinnati Prehospital Stroke Scale (CPSS); (2) symptom onset within 3 h; and (3) a blood glucose level ≧ 60 mg/dL via a pinprick test. One patient has a positive finding on the CPSS if any one of the following abnormalities is shown: facial palsy, arm weakness, and speech abnormalities. The method to perform the CPSS was the same as those in the original study [22]. These criteria were adopted and modified based on other prehospital stroke scales found in the literature, such as the CPSS, the Los Angeles prehospital stroke screen (LAPSS), the Ontario prehospital stroke screening tool (OPSS), and the Melbourne Ambulance Stroke Screen (MASS) [22‐25], and have been validated in a previous study [26]. If EMTs at the scene suspected that a patient was having a stroke, the patient would be examined to see whether he/she met the criteria. If the patient met the new prenotification criteria, the EMT would perform prehospital notification on the way to the receiving hospital. Then, the patient would be sent to the hospital as soon as possible. After receiving the prehospital notification, the personnel at the emergency department (ED) activated standard in-hospital protocols before the patient arrived. All protocols in participating hospitals attempted to establish a fast-track so that a prenotified patient took first priority for medical assessment by emergency physicians, brain imaging, and laboratory studies. However, there were some differences among the protocols; for example, in some hospitals, neurologists were consulted after intracranial hemorrhage was ruled out, but they were consulted before brain image examinations in others.

Before the prenotification criteria were utilized, all of the EMTs participated in a stroke education program, including symptom identification and care skills, in different time frames. During the 2-h education course, EMTs were taught how to perform the CPSS and check blood glucose level by pinprick test on presumed stroke patients. We taught the same method to perform CPSS from the original study [22]. In addition, the skills of querying the time of symptom onset were also taught and practiced in the course.

Although we encouraged EMTs to utilize the prenotification criteria for all patients whose complaints included any of the warning signs of stroke, as recommended by the AHA guidelines [9], it was up to the EMT’s discretion whether the prenotification criteria were used for any particular patient.

The study period was from September 1, 2012 to December 31, 2014. The inclusion criteria for study subjects were as follows: (1) patients over age 20 with discharge diagnoses of stroke or transient ischemic attack (TIA) and arriving at the ED within 3 h of symptom onset (≤3 h) via EMS; (2) patients receiving prenotification without having discharge diagnoses of stroke or TIA ≤ 3 h. Patients without prehospital or in-hospital data were excluded from our study.

The Taipei EMS stroke registry was established to measure, track, and improve stroke care beginning in September 2012. All 9 participating hospitals joined the registry. Trained hospital staff prospectively identified stroke patients over age 20 who arrived at the ED within 3 h of symptom onset via EMS, as well as all patients arriving with prehospital notification. Staff then collected data on demographics and prehospital and in-hospital quality indicators and management using a standardized, web-based data collection tool.

We extracted the registry data during the study period. The extracted data had been processed before we acquired it from the dataset, and thus the identity of each patient could not be identified. From the web-based registry, we collected data regarding age, sex, underlying diseases, scores on the National Institutes of Health Stroke Scale upon ED arrival, prehospital and in-hospital management time, and reasons why thrombolytic therapy was not given.

Our primary outcome was door-to-computed tomography (door-to-CT) time. The door-to-CT time was defined as the period from ED arrival to time of CT completion. The time of CT completion was obtained from the film printout or the digital image of the radiology report. The reason why we chose the door-to-CT time as our primary outcome was that there were few differences in management protocols before patients received CT examinations among hospitals; thus, it eased the effect of the different protocols from different hospitals. The secondary outcome was DTN time. The DTN time was defined as the time interval between ED arrival and time that the patient received their first bolus of tPA. The total prehospital management time included the period of time from the receipt of the call by EMS to the patient’s arrival at the hospital. In addition, we also evaluated the positive predictive value (PPV) and sensitivity of the prenotification calls and tried to understand the reasons why thrombolytic therapy was not given to patients presenting ≤ 3 h after stroke onset. The association between the volume of patients receiving thrombolytic therapy and DTN time in individual hospitals was also evaluated. The study received approval from the institutional review board of National Taiwan University Hospital.