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Detecting the start of an influenza outbreak using exponentially weighted moving average charts.

Steiner SH, Grant K, Coory M, Kelly HA - BMC Med Inform Decis Mak (2010)

Bottom Line: Influenza viruses cause seasonal outbreaks in temperate climates, usually during winter and early spring, and are endemic in tropical climates.The chart is shown to provide timely signals in an example application with seven years of data from Victoria, Australia.The EWMA control chart could be applied in other applications to quickly detect influenza outbreaks.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept. of Statistics, University of Waterloo, Ontario, Canada. shsteine@math.uwaterloo.ca

ABSTRACT

Background: Influenza viruses cause seasonal outbreaks in temperate climates, usually during winter and early spring, and are endemic in tropical climates. The severity and length of influenza outbreaks vary from year to year. Quick and reliable detection of the start of an outbreak is needed to promote public health measures.

Methods: We propose the use of an exponentially weighted moving average (EWMA) control chart of laboratory confirmed influenza counts to detect the start and end of influenza outbreaks.

Results: The chart is shown to provide timely signals in an example application with seven years of data from Victoria, Australia.

Conclusions: The EWMA control chart could be applied in other applications to quickly detect influenza outbreaks.

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Related in: MedlinePlus

Plot of the Average Run Length (ARL) in weeks by the Size of the Outbreak.
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Figure 5: Plot of the Average Run Length (ARL) in weeks by the Size of the Outbreak.

Mentions: Figure 5 shows how the EWMA ARL changes with μ. The EWMA very rapidly detects any outbreak with Poisson mean greater than about 6. Given the size of the outbreaks shown in Figure 1, we expect the EWMA chart to detect the typical seasonal influenza outbreak within one or two weeks of the outbreak's start. Note, however, that this analysis is only designed to give some indication of performance. To determine the ARLs we assumed a step change in the Poisson mean reflected the start of an influenza outbreak. In reality, an influenza outbreak is likely sudden but not instantaneous. Also, this analysis assumes outbreaks continue indefinitely at a constant rate. Smaller outbreaks may not be detected before they subside. However, our main goal is detecting large influenza outbreaks.


Detecting the start of an influenza outbreak using exponentially weighted moving average charts.

Steiner SH, Grant K, Coory M, Kelly HA - BMC Med Inform Decis Mak (2010)

Plot of the Average Run Length (ARL) in weeks by the Size of the Outbreak.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2909986&req=5

Figure 5: Plot of the Average Run Length (ARL) in weeks by the Size of the Outbreak.
Mentions: Figure 5 shows how the EWMA ARL changes with μ. The EWMA very rapidly detects any outbreak with Poisson mean greater than about 6. Given the size of the outbreaks shown in Figure 1, we expect the EWMA chart to detect the typical seasonal influenza outbreak within one or two weeks of the outbreak's start. Note, however, that this analysis is only designed to give some indication of performance. To determine the ARLs we assumed a step change in the Poisson mean reflected the start of an influenza outbreak. In reality, an influenza outbreak is likely sudden but not instantaneous. Also, this analysis assumes outbreaks continue indefinitely at a constant rate. Smaller outbreaks may not be detected before they subside. However, our main goal is detecting large influenza outbreaks.

Bottom Line: Influenza viruses cause seasonal outbreaks in temperate climates, usually during winter and early spring, and are endemic in tropical climates.The chart is shown to provide timely signals in an example application with seven years of data from Victoria, Australia.The EWMA control chart could be applied in other applications to quickly detect influenza outbreaks.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept. of Statistics, University of Waterloo, Ontario, Canada. shsteine@math.uwaterloo.ca

ABSTRACT

Background: Influenza viruses cause seasonal outbreaks in temperate climates, usually during winter and early spring, and are endemic in tropical climates. The severity and length of influenza outbreaks vary from year to year. Quick and reliable detection of the start of an outbreak is needed to promote public health measures.

Methods: We propose the use of an exponentially weighted moving average (EWMA) control chart of laboratory confirmed influenza counts to detect the start and end of influenza outbreaks.

Results: The chart is shown to provide timely signals in an example application with seven years of data from Victoria, Australia.

Conclusions: The EWMA control chart could be applied in other applications to quickly detect influenza outbreaks.

Show MeSH
Related in: MedlinePlus