Information Overload, the Index Medicus, and PubMed

Image by Nuevo Anden via Flickr

The growth of medical knowledge is difficult to visualize. One classic representation is the Index Medicus — a comprehensive index of medical journal articles — whose bound copies filled the shelves of medical libraries for 125 years. In 2004, however, the National Library of Medicine decided to stop publishing the Index. The first reason was practical: the Index Medicus had grown from 82 pounds in 1985 to an estimated 152 pounds in 2004. The second and more important reason was the widespread availability of the search engine PubMed — an electronic database of medical literature available for free via the Internet — which made the printed index obsolete. Compared to the Index Medicus, PubMed was more convenient, could be searched more easily, could be updated more quickly, and certainly weighed less. Copies of the Index Medicus are now a historical curiosity; many physicians now search the medical literature exclusively through PubMed.

The story of the Index Medicus and its successor, PubMed, illustrates three ideas.

First, the quantity of new medical information is more than any single physician can absorb, and keeping up to date with this expanding body of knowledge is challenging. As of April 2009, for example, PubMed contained information on 18,782,970 citations in the medical literature and was adding over 670,000 new entries per year. Doctors must not only absorb this flood of new ideas about treating, diagnosing, preventing, and understanding disease — deciding which information is relevant and which is not — but also learn how to apply and explain this knowledge to the patient sitting with them in the exam room or laying ill in a hospital bed.

Second, in parallel with this unprecedented expansion in medical knowledge, new media and technologies have emerged — of which PubMed is one example — which has made the task of searching, organizing, and retrieving relevant information easier. Potential sources of information for physicians include not only printed journal articles like those indexed in PubMed, but lectures, case conferences, and newer Internet resources such as reference tools (e.g., UpToDate), discussion groups, online expert systems, clinical resource tools, and podcasts.

Third, the expansion of medical information and proliferation of new technologies has required physicians to develop new skills and strategies to keep their knowledge current. Often, the availability of new knowledge overwhelms physicians’ ability to process it, a condition known as information overload. In physician’s offices, one symptom of information overload is the common spectacle of unread piles of medical journals stacked up on every available horizontal space.

While many medical schools now require classes on searching the medical literature and evidence-based medicine, few resources have been available designed to teach physicians how to learn and practice medicine more efficiently. (That's why, over two years ago, I started writing The Efficient MD blog.)

Since then, I'm glad to report that online resources for physicians have proliferated. Ways of improving efficiency and reducing information overload are now common topics on medical blogs. For example, see recents posts in Life in the Fast Lane, Clinical Cases and Images, and Musings of a Distractible Mind.

Thanks for reading!

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(Much appreciation to Jacque-Lynne Schulman, Stephen Greenberg, Margaret Vugrin, and Dean Giustini for helping me with an updated estimate of the weight of the Index Medicus. Any inaccuracies in this post are, of course, my own.)

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