Increased complaints of fever in the emergency room can identify influenza epidemics

In developing countries, it may be easier to use the reasons why patients come to the emergency room (ER) instead of sentinel practices to identify influenza epidemics.

We studied the reasons why adult patients present to the ER in order to attempt to predict increased hospital activity as a result of influenza. The daily frequency of presenting symptoms during the 30 days of maximal influenza activity was compared to the other days of the study period (335 days).

During the influenza period, more patients presented with fever, syncope or near syncope, cough, asthma attack, and paralysis than on the days outside of this period. On 50% of the days, eight or more patients presented with fever, an 8.36 (95% CI=4.6-15.19) higher frequency than during the rest of the year. During the subsequent year, days with excess presentations by patients with a principal complaint of fever predicted increased hospital activity due to influenza with no false-positive periods.

We conclude that an increase in the number of patients presenting to the ER complaining of fever can identify increased hospital influenza activity.