Telephone triage service data for detection of influenza-like illness.

W Katherine Yih,Ken Kleinman,Allyson Abrams,Richard Platt,Martin Kulldorff,Stanley Wang,Robert Harmon,Kathryn S Teates,Robert Pinner,Joel Mark Montgomery

doi:10.1371/journal.pone.0005260

Abstract

BackgroundSurveillance 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.Methods/Principal FindingsNational 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.ConclusionsTelephone 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.

Highlights

The principal objective of surveillance for influenza and influenza-like illness (ILI) is to guide public health prevention programs to mitigate the morbidity and mortality caused by annual influenza epidemics, which cause approximately 36,000 deaths each year in the United States [1]
Telephone triage data in the U.S are patchy in coverage and not a reliable source of ILI surveillance data on a national scale
In states displaying a higher correlation between the call data and the Centers for Disease Control and Prevention (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

Summary

Introduction

The principal objective of surveillance for influenza and influenza-like illness (ILI) is to guide public health prevention programs to mitigate the morbidity and mortality caused by annual influenza epidemics, which cause approximately 36,000 deaths each year in the United States [1]. In the U.S as well, data from national nurse telephone triage services, lacking laboratory confirmation, might be useful for ILI surveillance for reasons of timeliness and the potential to complement existing surveillance—it is possible that these data can be collected more quickly or efficiently than the weekly reports currently received by CDC, and they may be available in locations or at times during the year when conventional ILI surveillance systems do not operate. 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

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