The Aug 25, 2001 issue of The Lancet published an article titled "1966 and all that-when is a literature search done?" The article notes the importance on older medical literature, and with the recent death of a 24-year-old volunteer at John Hopkins because of lax research methods, medical literature searches are being called into question. Specifically, while many librarians are familiar with OLDMEDLINE, many researchers forget that MEDLINE only goes back to 1966, while OLDMEDLINE contains articles from 1958-1965.
The reason why OLDMEDLINE is not included in MEDLINE is because prior to 1965 there existed different original indexing standards. Older papers had many fewer subject headings, which do not correspond to currently used terms. In addition, the older articles do not have abstracts, which is why they are not a part of MEDLINE.
The National Library of Medicine is in the process of adding older citations at a rate of 1-2 years' worth per fiscal year, but it is important to realize that the older citations are still not part of current MEDLINE or PubMED. As a result, the Medical Library Association is in the process of writing guidelines or standards for literature searching.
Older literature can greatly contribute to many factors in the research process. Using a citation database such as Science Citation Index allow researchers to follow the chains of citations and discover associations and trends in research over time. Tracking citations chains is a legitimate method used by researchers. The value in looking at older citations can lead to new ways to investigate diseases and find "old clinical truths." As one researcher from the Netherlands is quoted "The value...is mainly scholarly, and leads to humility: when reading first descriptions of disease, or of mechanisms or of therapy, one often realizes how much was already known in that first description." The Hopkins incident has renewed an interest in making OLDMEDLINE accessible through PubMED or MEDLINE, but for the time being it is important to remember to consider OLDMEDLINE in conducting comprehensive literature searches.
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