Hi Anitha,

if I understand your question correctly, you should always report the RoB of the studies summarised in the systematic review. If the RoB is low, this should be clearly stated, so that the treatment effects arent over/ under-estimated. In the discussion section of your review, you can discuss why the study quality was low (or high) and what studies with a good design shoud look like. Hope this helps?

This is because the conclusion of a systematic review is not only based on numerical figure, such as a pooled odds ratio [OR] with 95% confidence intervals (CI) of the association between two variables in a meta-analysis.

Apart from the pooled effect size obtained from a systematic review, it is also necessary to assess the methodologic quality of the included studies in order to determine the level of confidence which the reader can have in the results drawn from a systematic review.

After performing a meta-analysis, it is necessary to describe the findings for each outcome in the text of the review with consideration of the potential impact of bias on the size or direction of the effect, the degree of heterogeneity and its possible sources (for meta-analysed data) and their clinical relevance.

Furthermore, it is also recommended to perform a series of sensitivity analysis to determine how the conclusions derived from a systematic review might be affected if [i] studies at unclear risk of bias are removed from the analysis, or if [ii] studies at a high risk of bias are included in the analysis.

Most importantly, during the initial data extraction process in a systematic review, it will be compulsory for the authors to perform a quality assessment of each of the included studies independently and in duplicate by at least two authors as part of the data extraction process. All those included studies shall be judged to have a high risk of bias (i.e. plausible bias that seriously weakens confidence in the results) if one or more criteria are not being met as described in the risk of bias tool.

An example of a risk of bias tool is provided by The Cochrane Collaboration, which is a tool for assessing risk of bias of each included study on six standard criteria: adequate sequence generation; concealment of allocation; blinded or objective assessment of primary outcome(s); adequately addressed incomplete outcome data; freedom from selective reporting; freedom from other risk of bias.

This means that for any systematic review that aims to strictly include only randomized, controlled clinical trials; then any studies which are not placebo-controlled will be considered to have a high risk of bias, which will usually be recommended to be excluded from the primary analysis. This is because the primary analysis will often be limited to only studies at low or unclear risk of bias.

Hence, the assessment of risk of bias for a systematic review shall be undertaken by more than one author during the initial data extraction process as part of the quality assessment of each included study (i.e. when all the search results have been screened to determine a list of included studies) as well as after performing the meta-analysis in order to describe the findings for each outcome in the text of the review with consideration of the potential impact of bias on the size or direction of the effect, and the clinical relevance of such bias.

Validity of Results: If a systematic review includes trials with a high risk of bias, the validity of its conclusions may be compromised. Bias in included studies can lead to over- or underestimations of the true effect of an intervention.

Quality Assessment: Systematic reviews aim to provide a comprehensive evaluation by including only high-quality studies or by assessing the risk of bias in each included study. Tools like the Cochrane Risk of Bias tool assess factors such as randomization, blinding, and selective reporting.

Interpretation of Findings: A high risk of bias in the included studies can complicate the understanding of the findings, making it difficult to discern whether observed effects are due to the intervention or are artifacts of the biases inherent in the studies.

Generalizability: Conclusions drawn from biased studies may not be generalizable to the wider, real-world population.

.Recommendations for Practice: The presence of bias can influence clinical guidelines and recommendations. Decision-makers rely on systematic reviews to form evidence-based guidelines; thus biased conclusions could lead to inappropriate clinical recommendations

In conclusion, addressing and minimizing the risk of bias in systematic reviews is crucial to ensure that healthcare professionals and policymakers make decisions based on the best available evidence.

The conclusion of a systematic review goes beyond numerical results, and requires assessing the methodological quality of the included studies to gauge confidence in the findings. Bias, heterogeneity, and clinical relevance must be considered, along with sensitivity analyses to test the robustness of conclusions. A proper risk of bias assessment, ideally performed independently by multiple authors, is crucial for ensuring the reliability of the results.

"The terms validity, quality, bias are often used interchangeably, but wrongly. It is useful to distinguish their meaning: the validity of a study is both external, evoking the notions of applicability and extrapolability, and internal, terms most frequently used to designate its methodological quality. The evaluation of the methodological quality of a study involves the search for bias (evaluation of the reliability of the results) but also a judgment on other elements (ethical approval, correct sample calculation, report in accordance with a reference consensus, etc.). As a reminder, a bias is a systematic error or deviation from the truth in results or conclusions. This bias can just as well overestimate or underestimate the real result or not influence it. It is therefore more correct to speak of risk of bias." (https://minerva-ebp.be/FR/Article/301)

Overall, any observed result is a priori subject to doubt. The assessment of the risks of bias (and of the methodological quality of the studies in a more global approach), should allow you to define a level of confidence (called level of evidence) linked to the observed results. The more correct the methodological quality of a study, the greater the level of confidence that you can bring to the observed result.

The risk of bias in systematic reviews can lead to inaccurate or misleading conclusions. If studies included in the review have flaws, such as poor design or selective reporting, it can overestimate or underestimate the effects of treatments, affecting the reliability of the review's findings.