Medical Info Searches on the Web

Nowadays, anyone who receives a medical diagnosis or is simply curious about some aspect of medicine often turns to the Web. Typically, people will try one of the major search engines such as Google. If you’ve experimented at all with online searching, you have seen the incredible number of “hits” that can be retrieved—often in the hundreds of thousands or even millions. For example, a simple search of Google on lung cancer finds over twenty-seven million pieces of information. If you use Google’s advanced search technique to find that specific phrase (click on Advanced Search or enter the words within quotation marks), this reduces the results to just fewer than ten million pages—hardly a manageable amount.

Selecting the most authoritative articles from this huge mass of information is challenging. While there are general guides for trying to judge the value of web pages, there is a better way. With a little practice, you can access the same detailed medical information that health care practitioners use. In the next paragraphs, I’ll describe some basic ways to fnd information in the major medical databases.

The largest and most respected collections of online information are the U.S. National Library of Medicine (NLM) databases. Before the days of general public access through the Web, the NLM maintained a computer database of medical information called Medline. All of this information and considerably more is now available to anyone with Internet access. General access is through a service called PubMed. You can visit the starting point through this link: U.S. National Library of Medicine

There is a detailed section on how to get the most out of these databases, accessible by following the link on the left of the page to ENTREZ HELP.These databases include more than sixteen million reports and other articles from MEDLINE and other life science journals dating back as far as the 1950s. PubMed includes links to full text articles and other related resources.

The U.S. National Library of Medicine link brings you to a search page. With so many articles and books indexed, just typing in a simple phrase like lung cancer today found 124,849 references. (All uses of retrieved numbers of citations in this article are examples taken from a search at the moment of writing; the results change constantly.) Even using quotation marks to restrict the search to the phrase only reduced the result to 49,882. This is where some more sophisticated searching techniques come into play.

If you can, it will be much easier to understand this process if you open a separate browser window and follow along with the examples described here. To help interpret the directions below, words that will be searched as examples are italicized. Terms that represent clickable buttons on the Web pages are in capital letters.

The phrase lung cancer seems to be the obvious way one might look for information on this disease. However, medical personnel, particularly researchers, do not always use common terms. So you might start by checking what the official term is for a specific condition. On the left of the home page (National Library of Medicine )is a list of links. In the second section on the left, under PubMed Services, you will see the words MeSH Database. MeSh stands for Medical Subject Headings. Clicking on this link takes you to a page to search this database. You also will see some short tutorials, in both audio and visual format, on how to conduct a search. I urge you to take the time to explore these quick tours to improve your skills.

If you search lung cancer on the MeSH page, at the top of the results screen you’ll see a list of suggested terms, which begin with lung cancers and other words. However, just below that you will see that lung neoplasms is listed as the #1 term. To the far right of the line with lung neoplasms is a highlighted link button, which would take you to a results page on PubMed. At the moment, there are 115,289 listings, still far too many to pursue, so let’s continue where we are at the moment..

Click on the lung neoplasms term. The result will be a list of subheadings with check boxes for each one. One obvious topic of interest is therapy. Put a checkmark here and then look a bit higher on the page where you see an option reading SEND TO. Use the drop-down menu and select the option reading SEARCH BOX WITH AND.

These terms appear in a search box in this fashion: "Lung Neoplasms/therapy"[MeSH]. If you click on the SEARCH PubMed button just below the terms, you’ll bring up a list of citations, roughly in order from newest to oldest, although some slightly older articles may be entered more recently. The total article retrieval now is 43,017, still a lot.

There are two ways to proceed at this point. If you see an interesting article title on the first few screens that seems right on target, look at the icon that resembles pages in the left-hand column. If the pages have several small lines, there is an abstract—a short summary—of the article available. If the page icon is blank, there is no abstract. You can click on the icon to read the summary. The summary page also includes a link to related articles as does the main list of retrieved articles.

Alternatively, you can try to narrow down the results even more. Use the browser’s BACK button to return to the MeSH page. Now check through the list of subheadings again. Perhaps you want to specify drug therapy. Use the CLEAR button just below the search box to remove the previous search phrase. Then put a check mark in the drug therapy box and repeat the steps to send this to the SEARCH BOX WITH AND. Now you can click the SEARCH PubMed box again and find that we’re down to 16, 826 articles. You can check out the most recent or continue to get more specific.

How about complications of drug therapy? Put a checkmark in the complications box but do not clear the previous search. When you use the SEND TO SEARCH BOX WITH AND, the new search now reads "Lung Neoplasms/drug therapy"[MeSH] AND "Lung Neoplasms/complications"[MeSH]. Follow the search PubMed link again and find 2,528 references. This is getting more reasonable if you limit yourself to the most recent research and related articles. You can, however, continue to narrow the search using the methods outlined above.

It is also possible to add terms using the SEND TO SEARCH BOX WITH OR option. For example, check out drug therapy OR diet therapy by adding a checkmark in the diet therapy box. Similarly, you can exclude material by using the SEND TO SEARCH BOX WITH NOT. There are other ways to limit searching by the journal the article appeared in, date, and so forth, but these are explained in the various tutorials mentioned earlier.

You are not limited to the subheadings that you saw on the MeSH page. Once you become familiar with the way the AND, OR, NOT operators work, you can do free-wheeling searches directly in the PubMed databases. For example, a hot topic right now in the prostate cancer area is the use of pomegranate juice in prevention and perhaps even treatment. Just enter “prostate cancer” AND “pomegranate juice” in the PubMed search box. It’s better to use the actual quotation marks on phrases to narrow the search when you are not using MeSH terms. You can get even fancier with your searches.

For a last example, try “blood pressure” AND ("vitamin E" OR "vitamin C") and you get 558 hits. The parentheses are there to be sure you get articles that are combined with blood pressure and either of the other terms. If you omit the parentheses, you will find 33,372 articles because you searched either blood pressure and vitamin E, or vitamin C by itself.

When you have a list of articles that seem the most pertinent, by paying a small fee you can obtain the full text. In some cases the full text is directly available through your search. Most of the time, though, you’ll need to pay to get the entire report or persuade your doctor to get it for you. If you have good public library service, often the library will order a photocopy for you through a process called Interlibrary Loan. There is a move on now to make the full text of many more published articles on PubMed, particularly from those individuals and centers that receive government funding, available free of charge.

I’ll mention just one more very worthwhile online source, the Clinical Trials database, Here you can locate ongoing trial approaches. Enter congestive heart failure in the search box on this site and you will find 152 studies. The same search operators that work in PubMed (AND, OR, NOT) also work in this database as the TIPS link explains. Adding a location, for example San Francisco, will find a medical center participating in the study.

Ensuring you find reliable information when health issues arise is extremely important. Doctors do not always explain things well, nor is every doctor necessarily up-to-date on the latest research. Searching the Web can retrieve both valuable and misleading information. As a consumer of medical services, particularly when facing a disease, you owe it to yourself to learn as much as possible about how to structure queries that you put to Web databases. Even in PubMed you may well find reports that are contradictory. Sorting these out will be the subject of another Suite101 article.

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