The Cochrane Database of Systematic Reviews consists of a rapidly growing collection of regularly updated systematic reviews of the effects of health care. They are prepared from analyses of randomised controlled trials.
Evidence is included or excluded on the basis of explicit quality criteria to minimise bias.
Data are often combined into a meta-analysis to increase the power of numerous small studies, each to small to produce a reliable result. Bailey and Love A companion to the well established text-book, this site contains case reports, multiple choice questions and sample chapters. This report of the 1998 Independent Review Group succinctly presents the evidence relating to the safety of silicone gel breast implants. It includes specific recommendations for their future use. The complete report can be downloaded in pdf format from this government site.