title: Data-driven approach of CUSUM algorithm in temporal aberrant event detection using interactive web applications.
abstract: OBJECTIVE
  In 2014/2015, Public Health Ontario developed disease-specific, cumulative sum (CUSUM)-based statistical algorithms for detecting aberrant increases in reportable infectious disease incidence in Ontario. The objective of this study was to determine whether the prospective application of these CUSUM algorithms, based on historical patterns, have improved specificity and sensitivity compared to the currently used Early Aberration Reporting System (EARS) algorithm, developed by the US Centers for Disease Control and Prevention.
  
  
  METHODS
  A total of seven algorithms were developed for the following diseases: cyclosporiasis, giardiasis, influenza (one each for type A and type B), mumps, pertussis, invasive pneumococcal disease. Historical data were used as baseline to assess known outbreaks. Regression models were used to model seasonality and CUSUM was applied to the difference between observed and expected counts. An interactive web application was developed allowing program staff to directly interact with data and tune the parameters of CUSUM algorithms using their expertise on the epidemiology of each disease. Using these parameters, a CUSUM detection system was applied prospectively and the results were compared to the outputs generated by EARS. The outcome was the detection of outbreaks, or the start of a known seasonal increase and predicting the peak in activity.
  
  
  RESULTS
  The CUSUM algorithms detected provincial outbreaks earlier than the EARS algorithm, identified the start of the influenza season in advance of traditional methods, and had fewer false positive alerts. Additionally, having staff involved in the creation of the algorithms improved their understanding of the algorithms and improved use in practice.
  
  
  CONCLUSIONS
  Using interactive web-based technology to tune CUSUM improved the sensitivity and specificity of detection algorithms.
authors.affiliation: Public Health Ontario, Suite 300, 480 University Avenue, Toronto, ON, M5G 1V2, Canada. Lennon.li@oahpp.ca.|Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada. Lennon.li@oahpp.ca.
authors.forename: Ye
authors.initials: Y
authors.lastname: Li
authors.affiliation: Public Health Ontario, Suite 300, 480 University Avenue, Toronto, ON, M5G 1V2, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Whelan
authors.affiliation: Public Health Ontario, Suite 300, 480 University Avenue, Toronto, ON, M5G 1V2, Canada.
authors.forename: Leigh
authors.initials: L
authors.lastname: Hobbs
authors.affiliation: Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
authors.forename: Wen Qi
authors.initials: WQ
authors.lastname: Fan
authors.affiliation: Public Health Ontario, Suite 300, 480 University Avenue, Toronto, ON, M5G 1V2, Canada.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Fung
authors.affiliation: Public Health Ontario, Suite 300, 480 University Avenue, Toronto, ON, M5G 1V2, Canada.
authors.forename: Kenny
authors.initials: K
authors.lastname: Wong
authors.affiliation: Public Health Ontario, Suite 300, 480 University Avenue, Toronto, ON, M5G 1V2, Canada.
authors.forename: Alex
authors.initials: A
authors.lastname: Marchand-Austin
authors.affiliation: Public Health Ontario, Suite 300, 480 University Avenue, Toronto, ON, M5G 1V2, Canada.
authors.forename: Tina
authors.initials: T
authors.lastname: Badiani
authors.affiliation: Public Health Ontario, Suite 300, 480 University Avenue, Toronto, ON, M5G 1V2, Canada.|Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Johnson
mesh_terms: D000465:Algorithms; D003141:Communicable Diseases / Q000453:epidemiology*; D004196:Disease Outbreaks / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D020407:Internet; D009864:Ontario / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods*; D011446:Prospective Studies; D014584:User-Computer Interface