Fig. 1.

Diagram of the literature search and selection process. A total of 252 citations comprising 151 publications in PubMed and 101 in the Cochrane Central Register were yielded between 1995 and 2011. We identified 55 potentially relevant studies that were retrieved and reviewed by titles and abstracts, 25 of which were further excluded because of the absence of a control group or lack of a detailed outcome index. Of the 30 possible studies meeting our inclusion criteria, 13 duplicate papers deriving from the same clinical centers were excluded, and finally 17 eligible full-text articles were included with the largest population and distinct observational index in this meta-analysis, which were further divided into two sections consisting of studies with comparison of Tac-based immunosuppressive regimens with steroids or not, as well as with induction agents or not