The identification of studies occurred through searches in the databases of Medline http://www.pubmed.gov, Embase www.embase.com, Lilacs www.bireme.br/bvs/I/ibd.htm and Cochrane Controlled Trials Register www.cochranelibrary.com/enter/.
La identificación de estudios se hizo mediante búsqueda en las bases de datos Medline http://www.pubmed.gov, Embase www.embase.com, Lilacs www.bireme.br/bvs/I/ibd.htm y Cochrane Controlled Trials Register www.cochranelibrary.com/enter/.