Search strategies.

<div><p>Background</p><p>Randomized-clinical trials (RCTs) are the gold-standard for comparing health care interventions, but can be limited by early termination, feasibility issues, and prolonged time to trial reporting. Adaptive clinical trials (ACTs), which are defined by pre-planned modifications and analyses that occur after starting patient recruitment, are gaining popularity as they can streamline trial design and time to reporting. As adaptive methodologies continue to be adopted by researchers, it will be critical to develop a risk of bias tool that evaluates the unique methodological features of ACTs so that their quality can be improved and standardized for the future. In our proposed methodological review, we will develop a list of risk of bias items and concepts, so that a risk of bias tool specific to ACTs can be developed.</p><p>Methods and analysis</p><p>We will perform a systematic database search to capture studies that have proposed or reviewed items pertaining to methodological risk, bias, and/or quality in ACTs. We will perform a comprehensive search of citation databases, such as Ovid MEDLINE, EMBASE, CENTRAL, the Cochrane library, and Web of Science, in addition to multiple grey literature sources to capture published and unpublished literature related to studies evaluating the methodological quality of ACTs. We will also search methodological registries for any risk of bias tools for ACTs. All screening and review stages will be performed in duplicate with a third senior author serving as arbitrator for any discrepancies. For all studies of methodological quality and risk of bias, we will extract all pertinent bias items, concepts, and/or tools. We will combine conceptually similar items in a descriptive manner and classify them as referring to bias or to other aspects of methodological quality, such as reporting. We will plan to generate pertinent risk of bias items to generate a candidate tool that will undergo further refinement, testing, and validation in future development stages.</p><p>Ethics and dissemination</p><p>This review does not require ethics approval as human subjects are not involved. As mentioned previously, this study is the first step in developing a tool to evaluate the risk of bias and methodological quality of ACTs. The findings of this review will inform a Delphi study and the development of a risk of bias tool for ACTs. We plan on publishing this review in a peer-reviewed journal and to present these findings at international scientific conferences.</p></div>