Accessibility of internet references in Annals of Emergency Medicine:: Is it time to require archiving?

Study objective: We seek to evaluate the accessibility of all Internet references appearing in Annals of Emergency Medicine from 2000, 2003, and 2005. Secondary objectives are to determine whether the number of Internet references is increasing and to describe how Internet references are inaccessible. Methods: We visually scanned all articles for references made in the printed version of Annals of Emergency Medicine for 2000, 2003, and 2005. We identified the Internet references and grouped them into 11 categories according to the results of entering the uniform resource locator (URL) into the Internet browser. Results: We identified 15,745 references published in Annals of Emergency Medicine. The proportion of Internet references increased from 1% of the total references in 2000 to 5.4% in 2005. Internet references were not readily accessible for 40 of 51 Internet references in 2000 (78%; 95% confidence interval [CI] 65% to 88%), 161 of 286 Internet references in 2003 (56%; 95% CI 50% to 62%), and 111 of 249 Internet references in 2005 (45%; 95% CI 39% to 51%). Inaccessibility was most commonly manifested by URLs that no longer link to active Web sites (172 of 312 inaccessible Internet references [55%]; 95% CI 50% to 61%) and URLs that linked to generic home pages where the authors' referenced material could not be found (115 of 312 inaccessible Internet references [37%]; 95% CI 32% to 42%). Conclusion: In Annals of Emergency Medicine, older Internet references appear to be less accessible than newer references. Internet reference archiving is one solution to preserving this information for future readers.