Objectives: Seasonal influenza causes high morbidity worldwide and high mortality in developing countries. As a result, the development of systems for seasonal influenza surveillance has been of great interest. The aim of this study is to explore the potential role of an Emergency Medical System (EMS) call centre to complement traditional surveillance systems of seasonal influenza.
Methods: Retrospective observational study in which data on influenza from the system of Notifiable Diseases List (Spanish acronym EDO) and Sentinel Physicians Network (Spanish acronym RMC) were compared with information on calls made to the Principality of Asturias EMS call centre that covers all the region population (1,027,659 inhabitants) based on a set of specific criteria to determine differences and explore this emergency call system as a complementary epidemiological surveillance system. Cases registered by different systems have been compared to the same 68 weeks period, from week 45 of 2011 to week 8 of 2013.
Results: RMC reported a total of 2,354 cases of influenza, EDO 43,071 cases and EMS call centre 4,360 "case calls" out of 180,720 total emergency calls. Case series of EDO and EMS call centre have shown a positive correlation (R = 0.42, p = 0.003). Case series from EMS call centre and RMC were correlated (R = 0.38, p = 0.007). Case series from EDO and RMC have shown a strong positive correlation (R = 0.91, p < 0.001). Correlation analysis of the cases reported by the three systems have shown a significant positive correlation between them (p < 0.001). The spike of EMS calls related to the studied influenza syndrome occurs one week in advance compared to traditional epidemiological surveillance systems.
Conclusions: EMS call centre data on influenza could be potentially used as a complementary surveillance system to the traditional epidemiological surveillance systems for influenza.
Keywords: emergency medical service; influenza; public health surveillance; surveillance system.