Current Contents Connect and PubMed—a comparison of content and currency

The past couple of years have witnessed an emergence of numerous current awareness services that have the ability to search PubMed, using predefined search strategies, and emailing the corresponding responses to clients.1 In many ways, these features duplicate the very popular Current Contents Connect®** Current Contents is a registered trademark of the Institute of Scientific Information. (CCC) Alert feature. As PubMed, and the adjunctive current awareness services are freely available, an investigation is therefore justified in order to assess the degree to which CCC can be supplanted by PubMed as a source for rapidly disseminated biomedical information. This would be the case if it can be demonstrated that PubMed covers both a significant portion of the relevant journals indexed in CCC and it provides access to these bibliographic records just as fast. A search of the literature in this subject area, using Library and Information Science Abstracts (LISA) and Information Science Abstracts both via Dialog, found nothing in the way of comparisons between CCC and PubMed. Articles published in this area either tended to make comparisons between different current awareness services2-4 or between Current Contents (on disk) and medline®† † medline is a registered trademark of the National Library of Medicine. /Index Medicus®†† † † Index Medicus is a registered trademark of the National Library of Medicine. (disk, or online through vendors).5-9 This points to a glaring omission in the literature considering the immense cost of CCC and the evolvement of the PubMed interface to medline into a rapid, efficient, and ubiquitous means of accessing the biomedical literature. Using the CCC title lists10 which are inventories of the serials indexed, broken down by edition, a statistically representative sample was taken from each of the relevant subfiles and searched in PubMed. The three subsets of particular interest to the author included: Agriculture, Biology and Environmental studies (ABE); Clinical Medicine (CM); Life Sciences (LS). If a title was found to be indexed in both sources then it was noted which source had indexed the most recent journal issue. This was done in order to quantify the relative currency of these two sources. In total, 1167 journal titles indexed in CCC were searched in PubMed. The data displayed in Table 1 represents the degree of overlap in journal coverage between CCC and PubMed broken down by subfile. In the ABE file there was a low degree of overlap; PubMed indexed 65 of the 343 titles searched. Conversely, of the 366 CCC titles in the CM subfile that were searched, 329, or 89.9%, were also indexed in PubMed. PubMed's coverage of the journals in the LS file was 88.9%, or 407 of 458. Table 2 represents this study's efforts at quantifying the relative currency of these two databases. During the content portion of the study, 801 titles were identified as being indexed by both sources. This group of titles became the data set from which the currency findings were generated. Of these 801 titles, 237, or 29.6%, had newer issues indexed by CCC when compared to PubMed. It was found that for 124 titles, or 15.5%, CCC had older issues indexed. By far the most common occurrence was when titles had the same issue indexed by both sources; this occurred with 430 of the 801 titles. The currency findings of these 801 titles are also broken down by subfile in Table 2. When contrasting the CM and the LS subfiles, one may note the striking difference in currency scores; CCC is newer 21.3% of the time vs. 36.9%. During this investigation the author was alerted to a disruption in the normal functioning of the loading of publisher-supplied citations into PubMed between 16 and 26 January 2001.11 Although the ABE and CM portions of this investigation were completed prior to 16 January, and should be unaffected, the LS portion, which commenced sometime after 26 January and concluded on 16 February 2001, is somewhat tainted. It was learned after completing this investigation that there was a delay in updating the publisher-supplied citations that extended past 26 January, and in fact was not fully rectified until 15 February.11 This fact certainly goes a way to explaining CCC's relatively greater currency for this subfile and is an obvious source for further investigation. The results in Table 1 faintly echo the findings of Mychko-Megrin. Comparing the CM edition to Index Medicus and using 7281 articles and book titles as his base-line, rather than actual journal titles, he reported a 57.9% overlap in coverage.6 Another point of interest reported elsewhere is the degree of title overlap between individual CCC subfiles. Bakker concluded that between the LS and CM subsets there is a 247, or 12% of total, title overlap.3 For Bakker, this overlap was easy to identify as she was working from a master list of indexed journals culled from the four current-awareness services that she was comparing. It is of some interest to theorize the extent of current inter-subset overlap and its effects on this present study. Without question, a journal indexed within multiple subfiles could be considered a ‘leading journal’, and as such its probability for inclusion in the journals indexed in PubMed would be intensified. As a final point of discussion, one may be quick to dismiss using CCC as a source for biomedical current awareness, with the knowledge that there is roughly 90% title overlap with PubMed for the combined editions of LS and CM. However, it must be stressed that 10% still represents roughly 250 titles of, in ISI's words, the ‘… world's most important and influential journals …’.12 This study also only compared certain CCC subfiles to PubMed. It must be noted that CCC goes far beyond the realm of biomedicine, and PubMed is certainly no match for CCC subfiles like Engineering, Computing and Technology or Physical, Chemical and Earth Sciences. Reversely, the CCC subfiles that could even remotely be attributed to biomedical coverage do not cover the bulk of journals that PubMed covers: ‘9613 serial titles, including 4514 titles currently indexed for medline, as of December 2000’.13 Indeed, abstract raw title counts aside, there will surely continue to be a debate as to which source indexes the ‘best’ titles. and whether or not one source, and one alone, can be counted on to deliver what is required. It is hoped that this investigation will make a significant addition to the field of health sciences librarianship as it relates to the comparison of these two sources of biomedical information. Librarians should now be better informed, as to the degree of title overlap and currency between CCC and PubMed. This is not only to the betterment of meeting client's needs, but also aids from an administrator's point of view as attempts to justify, or de-justify, the expense of CCC are made.

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