Searches of health-related bibliographic databases are generally the easiest and least time-consuming way to identify an initial set of relevant reports of studies. Some bibliographic databases, such as MEDLINE and EMBASE, include abstracts for the majority of recent records. A key advantage of these databases is that they can be searched electronically both for words in the title or abstract and by using the standardized indexing terms, or controlled vocabulary, assigned to each record (see Section 6.4.5).
The Cochrane Collaboration has been developing a database or register of reports of controlled trials called The Cochrane Central Register of Controlled Trials (CENTRAL). This is considered to be the best single source of reports of trials that might be eligible for inclusion in Cochrane reviews. The three bibliographic databases generally considered to be the most important sources to search for reports of trials – CENTRAL, MEDLINE and EMBASE – are described in more detail in subsequent sections.
Databases are available to individuals for a fee, on a subscription or on a ‘pay-as-you-go’ basis. They can also be available free at the point of use through national provisions, site-wide licences at institutions such as universities or hospitals, through professional organizations as part of their membership packages or free of charge on the internet.
There are also a number of international initiatives to provide free or low-cost online access to databases (and full-text journals) over the internet. The Health InterNetwork Access to Research Initiative (HINARI) provides access to a wide range of databases including The Cochrane Library and nearly 4000 major journals from a wide range of publishers in biomedical and related social sciences, for healthcare professionals in local, not-for-profit institutions in over 100 low-income countries.
The International Network for the Availability of Scientific Publications (INASP) also provides access to a wide range of databases including The Cochrane Library and journals. Journal titles available vary by country. For further details see:
o www.inasp.info/file/68/about-inasp.html
Electronic Information for Libraries (eIFL) is a similar initiative based on library consortia to support affordable licensing of journals in 50 low-income and transition countries in central, eastern and south-east Europe, the former Soviet Union, Africa, the Middle-East and south-east Asia.
o www.eifl.net/cps/sections/about
For more detailed information about how to search these and other databases refer to Sections 6.3.3 and 6.4.