Strengths and weaknesses of the study The main strength of our study is the large register of data collected, where we were able to prospectively collect a complete material of more than 5 000 red responses during the three month period, based on a population close to 820 000 inhabitants, about 20% of the Norwegian population. Limitations include NACA-scores in most of the cases being assessed retrospectively based on medical records, which might give a lower accuracy when registering the severity of the illness. Inhibitors,research,lifescience,medical Severity assessment in patients with chest pain can be difficult from medical records alone, but the records included the patients’ symptoms and clinical findings, making it possible

to achieve reliable registrations. Ideally the study would have included on-going clinical evaluation by the physicians on-site, in IOX1 mw addition to results and diagnoses

from the investigations for the patients admitted to the hospital. Our results are based solely Inhibitors,research,lifescience,medical on patients in an emergency situation defined by the EMCCs using the Index (red response), and thus Inhibitors,research,lifescience,medical undertriaged patients would not be included. Patients with chest pain assigned with a yellow response might be at risk of being undertriaged (“false negatives”), supporting the need for further studies on all patients with chest pain outside hospitals. The degree of urgency was set by trained nurses using the Norwegian Medical Index of Emergencies, but little is known about the validity of the Index and how the Index is used in the different EMCCs. A throughout evaluation and validation of the Index is needed. Previous studies The rate of acutely ill patients with chest pain in our study is similar to the findings in two other studies Inhibitors,research,lifescience,medical from Norway, reporting rates of 4.8 [7] and 5.4 [8]. The Inhibitors,research,lifescience,medical difference in median age between the genders, with the males being significantly younger, is in accordance with previous studies [14]. Recent studies from the UK [2,3] and the US [15] have shown that around 10% of calls to emergency

medical dispatch systems involve acute chest pain. A Norwegian publication from 2009 [16] showed that 22% of all the calls to the emergency number 113 ended in a red response, and it is intended that most of the chest pain incidents will be classified as a red response. In our study this would indicate that approximately 5% of all calls to the EMCCs involved not chest pain as the main complaint, given that all incidents with chest pain were classified as a red response. Meaning of study A substantial number of the patients were not in a life threatening medical situation. This sheds light on the challenges for the EMCCs in deciding the appropriate level of response in patients with acute chest pain. Overtriage is to some extent both expected and desirable to intercept all patients in need of immediate help, but it is also well known that overtriage is resource demanding.