Information scientists at the guideline center search several core databases for every guideline, depending on the study design. These databases include the Cochrane Database of Systematic Reviews, DARE, CENTRAL (Cochrane Central Register of Controlled Trials), MEDLINE, EMBASE, CINAHL, HEED, and NHS EED (National Health Service Economic Evaluation Database). Subject-specific databases and other sources of information may also be searched for certain topics. On the basis of the review questions developed by the guideline development group and the technical team, a search strategy is constructed, with the aim of being sensitive enough to retrieve all the studies of interest but precise enough not to produce an overwhelming number of results. Depending on the review area, searches may be limited by various criteria, such as date, language, study design, and participant age. Search filters may be used to aid consistency. Questions may be grouped together for the purposes of searching if they overlap. Search terms are agreed on with the guideline development group and are modified if needed. Searches are run again 6 to 8 weeks before the first draft of the guideline is finalized so that any studies published during the development period can be included. Further information can be found in chapter 5 of the NICE guidelines manual (1).