Evidence syntheses in child health

Evidence syntheses, also known as systematic reviews, differ from tradition al reviews in that they are scientific evaluations of existing studies. Sys tematic reviews have explicit and reproducible methods and, as with any oth er scientific endeavor, the result of an evidence synthesis or systematic r eview can be critically appraised. Many sources for high-quality evidence s yntheses now exist, with considerable support from government agencies to d evelop both the methods and the products of such reviews. Evidence synthese s can increase the efficiency and effectiveness of medical practice but fac e many hurdles, particularly in child health. These center around 4 areas: lack of high-quality primary studies, the difficulty of finding studies tha t do exist, the variability and usefulness of the outcome measures in child health, and problems with production and dissemination. Increasing attenti on to the need for high-quality child health research will help to ameliora te some of these issues, whereas solutions to others are under development or remain elusive.