[Syndromic surveillance of Influenza-like illness in primary care: a complement to the sentinel surveillance network for periods of increased incidence of Influenza].

OBJECTIVE: Epidemiological data on influenza is essential for resource management when the incidence of the disease in the population is very high, but not easily available in real-time. The objective of this study was to evaluate the use of a syndromic surveillance system for influenza-like illness in Primary Care (ILIsPC) and assess its level of agreement with the epidemiological data from the Influenza Sentinel Network. LOCALIZATION: Health centres and deputising medical services in the Balearic Islands. PARTICIPANTS: Data from 122 epidemiological weeks for each system were included. MAIN MEASURES: Data from January 1, 2007 to January 31, 2010 were compared. ILIsPC rates were obtained from the diagnoses registered in electronic health records of Primary Care clinics and deputising medical services. Data from Sentinel Network were obtained from weekly epidemiological reports. Intraclass correlation coefficient was calculated and Bland - Altman plot constructed.
RESULTS: There was good agreement between both measures, with an intraclass correlation coefficient of 0.88 (95% CI: 0.83-0.91). After constructing a Bland-Altman plot, the precision between both rates was greater during the periods of the highest influenza incidence.
CONCLUSIONS: We believe that the syndromic surveillance system ILIsPC, provides access to very useful data in real-time, especially during periods of high influenza incidence, such as during epidemics or the recent pandemic.