Improving risk of bias assessment and quality of reporting in clinical research

Avoidable research waste is a common problem in biomedical research. Including evidence at high risk of bias (RoB) and poor quality of reporting of studies are two causes of research waste, each contributing to a lack of reproducibility of research findings.
The research reported in this thesis aimed to explore different questions related to RoB assessment and inadequate reporting in clinical research. It consists of five different projects; two of them focused on sources of disagreements when assessing RoB for randomized controlled trials that were included in two different systematic reviews. A third project evaluated associations between trial characteristics, including RoB items as well as other features, and reported treatment effects. The other projects explored the quality of reporting in observational studies, through an evaluation of the knowledge and adherence to the reporting guideline STROBE and an analysis of the use of causal language in published observational studies.
Better guidance could improve agreement in the RoB assessment, especially in case of incomplete information. Additional initiatives can be taken to improve adoption of reporting guidelines, as shown in the study on STROBE. Our analysis of improper causal claims in observational research shows that further guidance for authors would also be welcome, on what constitutes a causal claim statement and how to justify or discuss any assumptions involved.