University of Southern Denmark Criteria-based dispatch of emergency medical services in non–traumatic subarachnoid haemorrhage Sonne,

Introduction: Timely admission to a facility capable of providing highly specialised treatment is key in patients with spontaneous subarachnoid haemorrhage. We aimed to determine the time elapsed from the initial emergency telephone call to arrival at a neurosurgical department. Also, we aimed to determine the ambulance dispatch criteria used and the activated prehospital responses. Methods: This was a retrospective study. Patients admitted in the Capital Region of Denmark within a 3.5-year period were identified in the Danish National Patient Register. Data were extracted from medical records and from automated telephone logs at the Emergency Medical Dispatch Centre. Results: Time intervals were available in 124 out of 262 patients and ambulance dispatch criteria in 98 patients. The median time from call to neurosurgical admission was 207.5 minutes. The dispatch criterion sudden severe headache had a sensitivity of 17.4%. An ambulance with lights and sirens was dispatched to 77% of patients and 28% were brought directly to a hospital with neurosurgical facilities. Conclusions: The median time from emergency call to neurosurgical admission was 3.5 hours. No single dispatch criterion detected the condition with an acceptable sensitivity. A high proportion of patients received an ambulance with lights and sirens, but more than two out of three were not initially brought to a hospital with neurosurgical facilities. Funding: the non-profit organisation Trygfonden Trial registration: NCT03786068 (www.clinicaltrials.gov) Non-traumatic subarachnoid haemorrhage (SAH) has a 30-day mortality of 35% [1]. Early clinical suspicion and timely expert treatment are critical [2]. A study from 2007-8 found a median time from symptom onset to neurosurgical admission of 5.5 hours in the Capital Region of Denmark [3], but on 1 May 2011 the prehospital system was reorganised. Health-related emergencies are now handled by healthcare professionals at an DANISH MEDICAL JOURNAL Dan Med J 2021;68(9): A02210152 1/9 emergency medical dispatch centre (EMDC). An electronic decision support system (DSS) using criteria-based dispatch was also introduced. In emergencies, citizens now call “1-1-2” to be triaged to the most appropriate prehospital response. As from 1 January 2014, out-of-hours non-urgent medical advice calls were no longer managed by on-call general practitioners, but by healthcare professionals at a dedicated telephone line of the EMDC named “1813”. However, telephone triage is a difficult task, and the choice of words and phrases used by the caller are critical for correct dispatch of emergency medical services [4]. Raising the suspicion of stroke already during the telephone call is vital to reduce ambulance on-scene time and transportation time, choose the right receiving hospital and reduce time spent in the emergency room [4]. The effect of a criteria-based dispatch system staffed by healthcare professionals on the time to neurosurgical care in patients with SAH has never been investigated. We aimed, firstly, to determine the time interval between emergency telephone calls to the EMDC and arrival of the patients at a neurosurgical department. Secondly, we aimed to determine the type of dispatch criteria used in patients with SAH, the proportion of patients who received an ambulance with lights and sirens, and the proportion of patients brought directly to a hospital with neurosurgical facilities. METHODS Design and setting: This retrospective study was conducted in the Capital Region of Denmark. The region has one hospital with neurosurgical facilities and nine referring hospitals. The EMDC is the point of contact in case of medical emergencies (“1-1-2”). During the study period, the EMDC also became the point of contact when outof-hours non-urgent medical advice was needed (“1813”). Dispatchers are medically trained. At “1-1-2”, they are aided by an electronic DSS [5]. Dispatchers at ́1813 ́ can choose to use the same electronic DSS and can convert a non-urgent 1813-call into an emergency 1-1-2-call. Participants: The cohort is described elsewhere [6]. Patients were aged 18 years or more, had a Danish civil registration number (CPR) [7] and had a discharge diagnosis of SAH (International Classification of Diseases, version 10; codes I60.0-I60.9) in the Danish National Patient Register [8]. Diagnoses were validated by medical record review. Their first admission was to one of the hospitals in the Capital Region of Denmark between 1 May 2011 and 31 December 2014. We included aneurysmal and non-aneurysmal non-traumatic SAH. Data sources and variables: Using medical records, we extracted the date and time of admission to the first hospital department (hereafter: referring department) and to the neurosurgical department. Using the CPR number, we identified calls to the EMDC within 28 days prior to admission to the referring department. We extracted the time of the call, the dispatch criterion, the activated response and the number of repeated calls. Due to system changes, time stamps and admission data were obtained for the entire study period for calls to the emergency number “1-1-2” and from 1 January 2014 for the non-urgent medical advice number “1813”. Data from the DSS were available only for the emergency number “1-1-2” and only until 31 December 2013. To calculate predictive values of the dispatch criteria, we extracted the total number of calls to the emergency number “1-1-2” and the total number of calls to “1-1-2” in which the symptom-specific dispatch criteria were used. Analyses: Continuous variables were reported as medians with interquartile range (IQR) and categorical variables as frequencies and percentages. Sensitivity, specificity, positive predictive value and negative predictive value were reported with 95% confidence intervals (95% CI). Predictors for direct admission to a hospital with neurosurgical facilities were assessed by odds ratio (OR) from logistic regression. Statistical analyses were performed in SAS version 9.4. DANISH MEDICAL JOURNAL Dan Med J 2021;68(9): A02210152 2/9 Trial registration: The study was approved by the Danish Data Protection Agency and the Danish Health and Medicines Authority. Approval by the Danish Committee System on Health Research Ethics was waived. Finally, the study was registered with clinicaltrials.gov (NCT03786068). RESULTS The original cohort consisted of 537 patients, of whom 262 were eligible for inclusion in this study. Among these, 131 had contacted the EMDC (“1-1-2” or “1813”), and in 124 patients the neurosurgical admission time was available (Figure 1). A total of 65% were women and the median age was 58.0 years (IQR: 48.0-67.0). The time interval between call and arrival at the referring department was 51.0 minutes (IQR: 39.0-60.0) and the time interval from call to neurosurgical admission was 207.5 minutes (IQR: 147.0-304.5). Among the 96 patients with no data on admission path, six had called the EMDC within 28 days without being admitted; and 15, 22, 25, and 34 of the patients had been admitted in the years 2011, 2012, 2013, and 2014, respectively. Three of the 34 patients admitted by other healthcare professionals and two of the 131 patients admitted via the EMDC had called within 28 days without being admitted. DANISH MEDICAL JOURNAL Dan Med J 2021;68(9): A02210152 3/9