Towards a more methodical use of protocols in systematic reviews

Written by Julia Bidonde and Catherine Boden, two of the authors of this project which will be presented at the Global Evidence Summit.

Journal editors and large funding bodies require that researchers conducting clinical trials of interventions make the existence of their trials transparent and a matter of public record by registering it in a publicly accessible database, often called a trial registry, such as Researchers can also publish the protocol for their clinical trial in an academic journal. For systematic reviewers this means that published randomised control trial (RCT) study protocols and trial registry records (we will call these ‘study protocols’ from now on) are an important source of information.

In fact, major evidence synthesis bodies have mandated searching for study protocols. Also, the new Cochrane risk of bias tool recommends using study protocols to evaluate reporting biases. How do we use study protocols in a review? When I have found a study protocol for my systematic review should I consider it an included study, a companion document to an included study, an ongoing study, awaiting classification, or excluded? If there is data available, can I use it? If so, how? How do I report protocols within the review?

We have evaluated the current guidance on using protocols (Boden 2017) and how they are currently being used in Cochrane systematic reviews (Boden in progress).  We recognize some important challenges, as there is no complete guidance on how protocols should be used in systematic reviews. Our current project aims to formulate ‘best practice’ recommendations to guide authors towards a more methodical use of protocols in systematic reviews.

How did we do this? We conducted a search for published and unpublished literature describing procedures for using protocols in evidence synthesis in bibliographic databases (Medline, EMBASE and CINAHL) and the websites of key systematic review collaborations (JBI, Cochrane, Campbell). The literature review findings were integrated with practices from a selected sample of Cochrane reviews to develop ‘best practice’ examples as concrete illustrations of procedures for each step (as described in the Cochrane Handbook) of a systematic review.

We aim to provide practical examples of the use of protocols through all stages of a systematic review. This will help reviewers know how to include protocols, particularly for evaluating and minimizing bias, and to facilitate transparent reporting. We are aware that there are many forms of evidence synthesis (systematic reviews, rapid reviews, diagnostic review, overviews of reviews) as well as new or updated reviews. Some, but not all, of the suggested examples may be applicable to other types of synthesis reviews


Boden C, Bidonde J, Busch A. Gaps exist in the current guidance on the use of randomized controlled trial study protocols in systematic reviews. Journal of clinical Epidemiology (2017) 85, 59-69.

Boden C, Bidonde J, Meneses-Echávez J, Busch A (in progress). Use of trial registry records and RCT study protocols in Cochrane systematic reviews of interventions: a content analysis.

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