The NHS Economic Evaluation Database (NHS EED) is published as part of The Cochrane Library (www.thecochranelibrary.com). Therefore, whenever users search The Cochrane Library, NHS EED records will be highlighted as well as Cochrane reviews. NHS EED is also available free online from the Centre for Reviews and Dissemination (CRD) web site (see www.york.ac.uk/inst/crd/crddatabases.htm). The version of NHS EED in The Cochrane Library is updated quarterly, whilst the CRD web site version is updated monthly.
A search of NHS EED and processing of these search results is recommended for all Cochrane reviews, especially those incorporating a critical review of health economics studies. NHS EED contains structured abstracts of full economic evaluations in health care, published in all languages, as well as bibliographic records of partial economic evaluations, methodology studies and reviews of economic studies. The NHS EED structured abstract format includes a critical commentary written by independent health economist peer reviewers and presents details of methods, results and other data in a summary format that is directly useful to inform critical appraisal and data collection in a critical review of health economics studies (see Sections 15.5.2 and 15.4.2).
It may sometimes be considered useful to include NHS EED abstracts of relevant full economic evaluation studies as an appendix to a published Cochrane review, as was done by Rodgers et al. and Fayter et al. (Rodgers 2006, Fayter 2007) (see also Section 15.6.2). If NHS EED does not contain a structured abstract of a full economic evaluation identified during searches conducted for a Cochrane review, it would be useful if the review authors could alert the Campbell and Cochrane Economics Methods Group (Box 15.10.a), so that NHS EED researchers can be made aware of the need to consider producing an abstract.
Searches of NHS EED and other specialist databases of health economics literature (see below) can be conducted using adaptations of review-specific search strategies, excluding both ‘economics search filters’ and other ‘study design search filters’. When searching The Cochrane Library, NHS EED is searched by default (i.e. unless the database is specifically excluded from the search using advanced search options). Information on how to search the CRD web site version of NHS EED can be accessed in CRD help pages at www.crd.york.ac.uk/crdweb/html/help.htm.
The desire to extend the principles of the UK-based NHS EED database to other European countries has led to the establishment of the European Network of Health Economic Evaluation Databases (EURONHEED), which is also freely available online (see http://infodoc.inserm.fr/euronheed/). NHS EED provides links to EURONHEED full abstract records only (from 2000 forward), so although a search of NHS EED will retrieve all full abstract records from both databases, it will not retrieve bibliographic records of partial economic evaluations, methodology studies or reviews of economics studies that are held in EURONHEED only.
NHS EED, EURONHEED and other specialist databases of health economics literature that may be searched for Cochrane reviews (including The CEA Registry, the Health Economic Evaluations Database (HEED) and Econlit) are fully described in a paper published by the NHS EED project team (Aguiar-Ibanez 2005). CRD also publishes an annotated online list containing details of these databases, including links to each database web site, at www.york.ac.uk/inst/crd/econ4.htm, as part of their ‘Information resources in health economics’ pages (www.york.ac.uk/inst/crd/econ.htm). This annotated list also includes details of selected general databases which include coverage of health economics literature (see also Section 15.3.1).
If the scope of the critical review of health economics studies is limited to those studies conducted alongside effectiveness studies that meet eligibility criteria for the effectiveness component of the review (see Section 15.2.3), then the sole aim of a supplementary search of NHS EED and other specialist databases is to check whether they include any structured abstracts of full economic evaluation studies conducted alongside included effectiveness studies. However, if the scope of the critical review of health economics studies is broader (see Section 15.2.3), then an additional aim is to identify further economic studies for potential inclusion in the review.