Gaps exist in the current guidance on the use of randomized controlled trial study protocols in systematic reviews

Abstract

Objectives: The use of trial registry records and randomized controlled trial (RCT) study protocols can assist systematic reviewers in evaluating and, possibly, minimizing publication and selective reporting biases. This study examined current guidance on the use of registry records and RCT study protocols from key systematic review organizations, institutes, and collaborations.

Study design and setting: Handbooks, guidelines, and standard documents from key systematic review organizations and the EQUATOR network database were identified. Textual excerpts providing guidance on the use of trial registry records, RCT protocols, and ongoing/unpublished studies were extracted independently by two reviewers and coded into a systematic review framework.

Results: Eleven documents published in English between 2009 and 2016 were included. Guidance for using RCT protocols and trial registry records was provided for 7 of 16 framework categories, and guidance for using unpublished and ongoing studies was available for 8 of 16 categories.

Conclusion: This study identified gaps and ambiguities in language in guidance on the use of RCT protocols and trial registry records. To encourage and assist reviewers to use trial registry records and RCT study protocols in systematic reviews, current guidance should be expanded and clarified.

Keywords: Publication bias; Randomized controlled trials; Selective reporting of outcomes bias; Study protocols; Systematic reviews; Trial registries.