Getting Started With Evidence-Based Research

A variety of databases can be reviewed when searchingfor medical information. These include indexes of primarysources comprised of journal articles and other originalresearch, secondary sources consisting of reviews ofresearch, and structured databases that collate abstracts.The leading collection of medical abstracts is MEDLINE,which covers thousands of quality medical journals. Theleading database of reviews of medical information ismaintained by the Cochrane Collaboration, which incorpo-rates methods of evidence-based medicine (EBM) to applyresults of medical research to clinical decision making. EBMproblem solving begins with formulating a clinical question,thoroughly searching databases, and appraising the validityand relevance of articles, and it ends with integrating theresults with clinical practice.

In more detail, some of the more common databases areas follows: MEDLINE/PubMed is the most widely usedprimary literature database containing abstracts. It coversover 4,600 journal titles published worldwide since 1966and contains 11,000,000 records. Although MEDLINE isthe first place to look for medical articles, it does notevaluate articles. On the Internet, MEDLINE can beaccessed through numerous portals, including a free sitethat is operated by the National Library of Medicine atwww.ncbi.nih.gov/entrez/query.fcgi.

EMBASE contains more than 9-million records from over4,000 journals since 1974. EMBASE is useful when carryingout medication-related searches and those that requireforeign material. Features that improve on those of MED-LINE include (1) drug literature searchable by chemical,trade, or manufacturer name; (2) enhanced biotechnology,pharmacy, and medical devices coverage; (3) medical devicetrade name and manufacturer names fields; and (4) preciseand reliable indexing using EMTREE, a hierarchicallyordered, synonym-based thesaurus with more than 45,000drug and medical indexing terms and 190,000 synonyms. Ithome page is www.elsevier.com/locate/embase. One mustpay for access.

CANCERLIT is a bibliographic database on cancer topicsthat contains more than 1.8-million citations and abstractsfrom over 4,000 different sources, including biomedicaljournals, proceedings, books, reports, and doctoral theses.Incorporation of nonjournal sources provides it withinformation that is not available on MEDLINE or EMBASE.Its address is http://www.cancer.gov/search/cancer_litera-ture. It is free.

CINAHL covers literature for nursing and allied healthdisciplines, starting in 1982. It covers 1,000 English-language nursing and allied health journals. Some nursingmaterials indexed herein are not listed elsewhere and may beparticularly helpful for research on nursing issues. Theaddress is www.cinahl.com, and a fee is required for use.

Current Contents indexes over 7,500 journals in thenatural and social sciences. It subsumes Clinical Medicine,which addresses anatomy, anesthesiology, clinical psychiatryand psychology, internal medicine, nuclear medicine, oncol-ogy, pediatrics, and surgery, and Current Contents LifeSciences, which covers biochemistry, biophysics, endocrinol-

ogy, genetics, immunology, microbiology, molecular biology,neuroscience, pharmacology, physiology, and toxicology.Current Contents contains material from many sources,some of which are not covered by MEDLINE, butunavailability of these additional materials will usually notimpede a search for medical evidence. Its use requirespayment, and the address is www.isinet.com.

The Cochrane Collaboration is a creation of panels ofexperts. Reviewers assess studies on particular subtopics andselect those that meet strict EBM criteria. ‘‘Meta-analyses’’are performed on the chosen studies, and presumptiveconclusions are drawn. The Cochrane Database contains theCochrane Controlled Trials Register, a bibliographic data-base of definitive controlled trials, as well as the CochraneDatabase of Systematic Reviews.

Cochrane is an essential tool for using evidence medicinebecause other major bibliographic databases cover less thanhalf of the world’s literature and are biased toward Englishlanguage publications. Much evidence is unpublished, butunpublished evidence may be important. Moreover, informa-tion that is readily available elsewhere in textbooks, editorials,and reviews may not been prepared systematically andconsequently may be unreliable or misleading. The CochraneLibrary solves many of these problems. Published on aquarterly basis and made available on CD-ROM and via theInternet, it is the best single source of reliable evidence on healthcare topics. Abstracts of reviews are free, but the completereviews must be purchased at http://www.cochrane.org.

EBM Reviews, ACP Journal Club covers EBM medicalliterature published in Evidence Based Medicine, ACP JournalClub, and Cochrane Database of Systemic Reviews. TheAmerican College of Physicians and the British MedicalJournal Publishing group publish these journals, the editors ofwhich screen other top clinical medicine journals to identifyrelevant studies in various medical specialties. Enhancedabstracts of the chosen articles and commentaries on thevalue of the published findings are provided in full text in thisdatabase, which in terms of importance for EBM research iscomparable to the Cochrane databases. A number of services,such as www.ovid.com, will link to this for-fee resource.

Database of Abstracts of Reviews of Effectiveness is afull-text database of critical assessments of systematicreviews. It is another important tool founded on the preceptsof EBM. The National Health Service assembles it in theUnited Kingdom. It is free and available at nhscrd.york.a-c.uk/darehp.htm.

Clinical Evidence summarizes the latest research evidenceon the effectiveness of common treatments and preventionstrategies for frequently experienced medical conditions.Compiled by the publishers of the British Medical Journal, ittoo hews to the principles of EBM. Free in the UnitedKingdom, it is available through the United HealthFoundation in the United States. Although not as compre-hensive as the Cochrane databases, it addresses some veryuseful questions. On the Internet, the portal is at http://www.clinicalevidence.com.

NOAH SCHEINFELD, MD

572 KOKOSZKA AND SCHEINFELD: CRYOSURGERY FOR BCC Dermatol Surg 29:6:June 2003