Supporting Informed Decision Making Online in 20 Minutes: An Observational Web-log Study of a PSA Test Decision Aid

Natalie Joseph-Williams*, Rhodri Evans, Adrian G. K. Edwards, Robert G. Newcombe, Patricia Wright, Richard P. Grol, Glyn Elwyn

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

19 Citations (Web of Science)


Web-based decision aids are known to have an effect on knowledge, attitude, and behavior; important components of informed decision making. We know what decision aids achieve in randomized controlled trials (RCTs), but we still know very little about how they are used and how this relates to the informed decision making outcome measures.To examine men's use of an online decision aid for prostate cancer screening using website transaction log files (web-logs), and to examine associations between usage and components of informed decision making.We conducted an observational web-log analysis of users of an online decision aid, Prosdex. Men between 50 and 75 years of age were recruited for an associated RCT from 26 general practices across South Wales, United Kingdom. Men allocated to one arm of the RCT were included in the current study. Time and usage data were derived from website log files. Components of informed decision making were measured by an online questionnaire.Available for analysis were 82 web-logs. Overall, there was large variation in the use of Prosdex. The mean total time spent on the site was 20 minutes. The mean number of pages accessed was 32 (SD 21) out of a possible 60 pages. Significant associations were found between increased usage and increased knowledge (Spearman rank correlation [rho] = 0.69, P <.01), between increased usage and less favorable attitude towards PSA testing (rho = -0.52, P <.01), and between increased usage and reduced intention to undergo PSA testing (rho = -0.44, P <.01). A bimodal distribution identified two types of user: low access and high access users.Increased usage of Prosdex leads to more informed decision making, the key aim of the UK Prostate Cancer Risk Management Programme. However, developers realistically have roughly 20 minutes to provide useful information that will support informed decision making when the patient uses a web-based interface. Future decision aids need to be developed with this limitation in mind. We recommend that web-log analysis should be an integral part of online decision aid development and analysis.ISRCTN48473735; (Archived by WebCite at
Original languageEnglish
Article numbere15
JournalJournal of Medical Internet Research
Issue number2
Publication statusPublished - 2010


  • decision aid
  • informed decision making
  • internet
  • prostate cancer
  • prostate specific antigen (PSA) test
  • user tracking
  • web-log
  • website transaction log file

Cite this