![]() ![]() There are many providers of access to MEDLINE, but you may want to access it directly through the US National Library of Medicine at. You can now search MEDLINE, free of charge, on the Internet. Other sources of information that you could use to identify citations of RCTs are traditional bibliographic databases such as MEDLINE or EMBASE. More information on this database and other products of the Cochrane Collaboration can be obtained from the Internet at. The complete database is available on CD-ROM and is updated four times a year. This has been achieved not only through the development of high yield strategies to search bibliographic databases, but also through extensive hand searching of journals to identify studies that cannot be identified efficiently by electronic searches or that are not indexed in bibliographic databases. Perhaps the most advanced and comprehensive source of RCTs in health care is the Cochrane Controlled Trials Database, which contains citations for more than 150,000 controlled trials identified through the collective effort of members of the Cochrane Collaboration (see below) to improve the identification of primary studies. All existing databases are incomplete (one of the main problems being the poor access to unpublished trials) and use coding systems that cannot cope with the diversity of topics in health care. This information explosion is compounded by the fact that there is not a single source of information that could provide easy and reliable access to all randomised controlled trials (RCTs) on a given topic. 3 In some areas, the time it takes for the number of published trials to double is less than 10 years. 1, 2 It is difficult to estimate the total number of trials that have been completed to date, but it is thought to be in the hundreds of thousands. It has been estimated, for example, that over 2 million articles and more than 17,000 biomedical books are published annually. The main problem derives from the speed with which the literature is growing. What are the main impediments to identifying all relevant trials on a given topic? My intention here, as in the rest of the book, is to highlight the most relevant information, directing you to more comprehensive sources that you could consult at your own convenience. ![]() As in previous chapters, most of the issues that I discuss deserve a chapter and have been addressed more extensively elsewhere. In this chapter, I introduce you to the identification of trials and the role of reviews of multiple trials to guide health care decisions. Identifying and synthesising the information from all relevant trials to guide a particular decision are not, however, easy tasks. You will also want to take into account other types of information (see Chapter 7). If you want to make decisions based on the best available knowledge, I am sure that you would like to consider as many relevant trials as possible. The corollary is that it may be risky for you and for your patients to make decisions based on the information from a single trial. Sometimes, different trials on the same topic have totally opposite results. As these trials are conducted in different groups of people, in different settings, and use the interventions differently, it is unlikely that they will provide identical results. Often you will find more than one trial that addresses your question or a very similar research question. Clinical practice guidelines based on sound evidence help practitioners improve the care they offer patients.The Cochrane Library is the most comprehensive source of evidence, especially from RCTs, needed to make informed health care decisions.The quality of reviews should be assessed.Meta-analysis increases the precision and conclusions of a review but can be prone to bias.Narrative and systematic reviews are the two major types of review articles used as tools to guide health care decisions.Use bibliographic databases, prepared summaries, and common interest groups to access and use RCTs.Reporting and interpreting individual trials: the essentialsįrom individual trials to groups of trials: reviews, meta-analyses, and guidelinesįrom trials to decisions: the basis of evidence based health careĦ From individual trials to groups of trials: reviews, meta-analyses, and guidelines Bias in RCTs: beyond the sequence generationĪssessing the quality of RCTs: why, what, how, and by whom? ![]()
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