Where are they now? A case study of health-related Web site attrition.

backgroundWhen considering health-related Web sites, issues of quality generally focus on Web content. Little concern has been given to attrition of Web sites or the "fleeting" nature of health information on the World Wide Web. Since Web sites may be available for an uncertain period of time, a Web page may not be a sound reference.

objectiveTo address the issue of attrition, a defined set of health-related Web sites was examined at two separate time intervals.

methodsTo determine the degree of attrition, Web sites obtained and recorded from a previous study were revisited approximately three years later. From December 1998 to May 1999, 184 Web sites were collected from which health claims were identified. During May and June 2002, the previously recorded URL for each Web site was entered into the address field of the browser Netscape Navigator. It was documented whether the original Web site could not be found, moved to a different URL location, or the URL and site location was found unchanged from the original search. For a Web site whose URL remained unchanged, it was also noted whether the site had maintained currency, (i.e. updated) since the original posting. To ensure that inaccessibility may not be due to temporary server problems, another attempt was made to access the sites at different periods of time.

resultsWhen each URL address from the original set of 184 Web sites was re-entered into the address field of the browser, 108 (59%) of the sites could not be found, 31 (17%) had moved to a new URL address, and 45 (24%) of the sites could be found from the original URLs obtained in the previous study. Of the Web sites that moved to a new URL address, 7 sites provided a link from the original URL to redirect the viewer to the new location. Of the Web sites still in existence, 17 (38%) provided update information from the original posting. CONCLUSIONS. It can be difficult to locate information that was previously found on the Web, and if a reference to an item is provided, there is no guarantee that viewers will be able to find the site at a later time. Enhancements in Web technologies such as the Internet Archive may improve this situation. Future research that is directed toward making sure Web site viewers know the site will be accessible at a later time will enhance the Web as a valuable medical information resource.