Chapter 13: Assessing risk of bias due to missing results in a synthesis focuses on the causes of missing evidence, such as studies that aren't published or non-significant outcomes aren't reported. It then describes a framework for describing the assessment of missing results.
The language on this topic has changed over the years.
While the terminology has changed, the intent is the same: determine what evidence is missing in the final analysis and how does that impact the summary of evidence.
Any systematic deviation that results in a potential skewing away from the truth of the results should be evaluated and reported. The PRISMA reporting guidelines for a protocol and for the manuscript all include items for assessing these types of biases.
Non-reporting biases encompass a variety of categories. The Catalogue of Bias (Catalogue of Biases. Richards GC, Onakpoya IJ. Reporting biases. In: Catalog Of Bias 2019) refers to reporting bias as, "A systematic distortion that arises from the selective disclosure or withholding of information by parties involved in the design, conduct, analysis, or dissemination of a study or research findings". It lists the following types of reporting biases:
This page will be updated as new tools and resources become available.
Chiocchia V, Nikolakopoulou A, Higgins JPT, Page MJ, Papakonstantinou T, Cipriani A, Furukawa TA, Siontis GCM, Egger M, Salanti G. ROB-MEN: a tool to assess risk of bias due to missing evidence in network meta-analysis. BMC Med. 2021 Nov 23;19(1):304. doi: 10.1186/s12916-021-02166-3. PMID: 34809639; PMCID: PMC8609747.