For a health related systematic review, the first place to look is the Cochrane Library (previously called EBM reviews). This contains several databases:
- Cochrane Reviews - the full text of Cochrane systematic reviews of the effects of health care interventions;
- Database of Abstracts of Reviews of Effectiveness (DARE) - critical assessments and structured abstracts of good systematic reviews published elsewhere;
- Cochrane Central Register of Controlled Trials (CENTRAL) - bibliographic information on controlled trials;
- Health Technology Assessment reports (HTA) - assessments of healthcare interventions;
- NHS Economic Evaluation Database (NHSEED) - published economic evaluations of health care interventions.
With the exception of Cochrane Reviews, many of the references indexed in the Cochrane Library will be found using databases such as Medline, but the Cochrane Library only indexes studies which have been evaluated and found to be methodologically-sound.
Each subject area has several large well-established databases which should form the basis of your review.