Ovid MEDLINE, ISI Web of Knowledge, Cochrane CENTRAL
and SCOPUS databases were searched with no restriction
on year or language of publication up to December 2010. A broad
search strategy was used to improve sensitivity and to include any
type of public health intervention. For each disease/issue, specific
key words and/or MeSH terms were used (Table S1) and the
search was combined with ‘‘systematic review’’ or ‘‘meta-analysis’’.
Reference lists from obtained articles were screened for additional
relevant reviews. No protocol has been published for this
systematic review.