One aim of this study is to find and describe articles on methodological issues concerning the incorporation of multiple types of study designs in systematic reviews on health care interventions. Another aim is to evaluate methods studies that have assessed whether reported effects differ by study types. Finally, we aimed to identify and JQ1 summarize qualitative evidence sufficient enough to guide finding and integrating the right research design for answering various clinical questions within systematic reviews of health care interventions. Methods While preparing this systematic review, we endorsed the PRISMA statement, adhered to its principles and conformed to its checklist (Table S1). Inclusion criteria We included articles reporting on how to integrate different study designs in systematic reviews of health care interventions.

We did not include articles merely describing advantages and disadvantages of various designs. We also included articles reporting different results of a particular outcome that depend on the type of design such as in a comparison of a randomized vs. a nonrandomized controlled design. Since we concentrated on the reporting of various study designs, we did not specify on the type of participants, interventions, comparisons, outcomes. Search strategy We searched PubMed, the Cochrane Database of Systematic Reviews, and the Cochrane Methodology Register on 31 March 2012. The search strategy is detailed in Table 1. Terms and syntax used for the search in PubMed were also used for the Cochrane Libarary.

The MeSH term “Randomized Controlled Trials as Topic”[MeSH] aims to specifically identify RCTs [9] while the MeSH term “Epidemiologic Studies”[Mesh] comprises Dacomitinib nonrandomized study designs [10]. We combined terms of the controlled vocabulary MeSH with text words. We searched PubMed and the Related citations function in PubMed tool to find some pertinent articles that appeared to represent the topic of the present revew. We adopted candidate text words reported by those articles in the title or the abstract to build a search strategy for nonrandomized or observational studies [11-13]. Table 1 Search strategy. Study selection We imported the bibliographic data of the search results into an EndNote X4 database. Two reviewers assessed independently title and/or abstract whether randomized controlled trials and nonrandomized studies were addressed at the same time in any type of article. Disagreements were resolved by discussion. Full texts were ordered if we agreed on potentially relevant references and if disagreements could not be resolved.