Interlibrary loan in U.S. health sciences libraries: journal article use

Health sciences libraries in the United States use the National Library of Medicine (NLM) DOCLINE system to request more than two million items annually through interlibrary loan (ILL). Ninety-seven percent of all ILL requests are for journal articles. In this study, NLM analyzed four million ILL requests entered into the DOCLINE system during two twelve-month periods ending September 30, 1992. The requests were analyzed at both the journal title level and article level. Data for the two years were found to be remarkably similar. Results showed that a large number of journals are required to fill ILL requests and that there is a relatively low number of repeat requests for most journal articles. Seventy-six percent of journal articles analyzed were requested only once, and fewer than 1% were requested more than ten times. About 39% of journals used to fill ILL requests were indexed in MEDLINE at some time, while 84% of the articles supplied were indexed in MEDLINE. Ninety-two percent of articles supplied were from English-language journals. Sixty-seven percent of articles were published in the most recent five years, and 85% in the most recent ten years. The 100 most frequently requested articles for each of the two years were examined to determine characteristics such as language, where they were indexed, and the subject matter. This study has provided valuable information for planning of NLM's interlibrary document delivery services and also should have significance for libraries and other organizations involved in document delivery.