How credible is lay health information on the World Wide Web? - A study of information about the effects of interventions

Background: The World Wide Web is a source to a wealth of health information that was previously unavailable to lay people. Formal studies have raised concerns about the credibility of online materials on the Web; most of them have been performed on English-language websites. Objectives: To investigate the credibility of Norwegian-language lay information about the effects of interventions on the World Wide Web. Methods: I performed a cross-sectional study of Norwegian lay health webpages on two specific topics: 1) Effect of low glycemic diets for weight reduction. 2) Effects of taking extra calcium supplementation during pregnancy to prevent pre-eclampsia and other related outcomes. Webpages were identified via four search engines and SMIL. Information on the included webpages was compared to the results of Cochrane reviews. I used a set of commonly used technical criteria to evaluate the transparency of webpages/sites. Furthermore, I compared the Webpages compliance with the criteria to their accuracy scores to see if there was an association between accuracy (information credibility) and the technical criteria (surface credibility). Results: 56 webpages were included, 49 from commercial providers. Overall, only above 40% of the webpages were evaluated as accurate. The low glycemic diets web pages were more inaccurate than the calcium supplementation webpages. There were no apparent differences between accurate webpages and inaccurate webpages in complying with the technical criteria. Conclusion: Lay health information on the Web seems to be inaccurate, unclear and sometimes inconsistent. Technical criteria will not sufficiently distinguish accurate materials from inaccurate materials. Further research is needed on other, more clinical topics to ensure the inclusion of public agency websites