title: Disease Monitoring and Health Campaign Evaluation Using Google Search Activities for HIV and AIDS, Stroke, Colorectal Cancer, and Marijuana Use in Canada: A Retrospective Observational Study.
abstract: BACKGROUND
  Infodemiology can offer practical and feasible health research applications through the practice of studying information available on the Web. Google Trends provides publicly accessible information regarding search behaviors in a population, which may be studied and used for health campaign evaluation and disease monitoring. Additional studies examining the use and effectiveness of Google Trends for these purposes remain warranted.
  
  
  OBJECTIVE
  The objective of our study was to explore the use of infodemiology in the context of health campaign evaluation and chronic disease monitoring. It was hypothesized that following a launch of a campaign, there would be an increase in information seeking behavior on the Web. Second, increasing and decreasing disease patterns in a population would be associated with search activity patterns. This study examined 4 different diseases: human immunodeficiency virus (HIV) infection, stroke, colorectal cancer, and marijuana use.
  
  
  METHODS
  Using Google Trends, relative search volume data were collected throughout the period of February 2004 to January 2015. Campaign information and disease statistics were obtained from governmental publications. Search activity trends were graphed and assessed with disease trends and the campaign interval. Pearson product correlation statistics and joinpoint methodology analyses were used to determine significance.
  
  
  RESULTS
  Disease patterns and online activity across all 4 diseases were significantly correlated: HIV infection (r=.36, P<.001), stroke (r=.40, P<.001), colorectal cancer (r= -.41, P<.001), and substance use (r=.64, P<.001). Visual inspection and the joinpoint analysis showed significant correlations for the campaigns on colorectal cancer and marijuana use in stimulating search activity. No significant correlations were observed for the campaigns on stroke and HIV regarding search activity.
  
  
  CONCLUSIONS
  The use of infoveillance shows promise as an alternative and inexpensive solution to disease surveillance and health campaign evaluation. Further research is needed to understand Google Trends as a valid and reliable tool for health research.
authors.affiliation: School of Public Health and Health SystemsFaculty of Applied Health SciencesUniversity of WaterlooWaterloo, ONCanada.
authors.forename: Rebecca
authors.identifier: 0000-0002-7064-1749
authors.initials: R
authors.lastname: Ling
authors.affiliation: School of Public Health and Health SystemsFaculty of Applied Health SciencesUniversity of WaterlooWaterloo, ONCanada.
authors.forename: Joon
authors.identifier: 0000-0001-8593-9321
authors.initials: J
authors.lastname: Lee
keywords: Internet; information seeking behavior; public health informatics