MOOSE Checklist for Meta-analyses of Observational Studies Item No Recommendation Reported on Page No Reporting of background should include 1 Problem definition 2 Hypothesis statement 3 Description of study outcome(s) 4 Type of exposure or intervention used 5 Type of study designs used 6 Study population Reporting of search strategy should include 7 Qualifications of searchers (eg, librarians and investigators) 8 Search strategy, including time period included in the synthesis and key words 9 Effort to include all available studies, including contact with authors 10 Databases and registries searched 11 Search software used, name and version, including special features used (eg, explosion) 12 Use of hand searching (eg, reference lists of obtained articles) 13 List of citations located and those excluded, including justification 14 Method of addressing articles published in languages other than English 15 Method of handling abstracts and unpublished studies 16 Description of any contact with authors Reporting of methods should include 17 Description of relevance or appropriateness of studies assembled for assessing the hypothesis to be tested 18 Rationale for the selection and coding of data (eg, sound clinical principles or convenience) 19 Documentation of how data were classified and coded (eg, m