Telephone triage service data for detection of influenza-like illness.
BACKGROUND
Surveillance for influenza and influenza-like illness (ILI) is important for guiding public health prevention programs to mitigate the morbidity and mortality caused by influenza, including pandemic influenza. Nontraditional sources of data for influenza and ILI surveillance are of interest to public health authorities if their validity can be established.


RESULTS
National telephone triage call data were collected through automated means for purposes of syndromic surveillance. For the 17 states with at least 500,000 inhabitants eligible to use the telephone triage services, call volume for respiratory syndrome was compared to CDC weekly number of influenza isolates and percentage of visits to sentinel providers for ILI. The degree to which the call data were correlated with either CDC viral isolates or sentinel provider percentage ILI data was highly variable among states.


CONCLUSIONS
Telephone triage data in the U.S. are patchy in coverage and therefore not a reliable source of ILI surveillance data on a national scale. However, in states displaying a higher correlation between the call data and the CDC data, call data may be useful as an adjunct to state-level surveillance data, for example at times when sentinel surveillance is not in operation or in areas where sentinel provider coverage is considered insufficient. Sufficient population coverage, a specific ILI syndrome definition, and the use of a threshold of percentage of calls that are for ILI would likely improve the utility of such data for ILI surveillance purposes.
Yih
W Katherine
WK
Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, MA, USA. katherine_yih@hphc.org
Teates
Kathryn S
KS
Abrams
Allyson
A
Kleinman
Ken
K
Kulldorff
Martin
M
Pinner
Robert
R
Harmon
Robert
R
Wang
Stanley
S
Platt
Richard
R
D002487:Centers for Disease Control and Prevention, U.S.; D006801:Humans; D007251:Influenza, Human / Q000175:diagnosis* / Q000453:epidemiology; D013689:Telephone; D014218:Triage; D014481:United States / Q000453:epidemiology