What type of bias can affect systematic reviews when selecting studies for inclusion?

Publication bias can profoundly impact systematic reviews by skewing the results toward studies that have been published, often favoring those with positive or significant outcomes. This bias occurs because studies with negative or inconclusive results are less likely to be submitted for publication or to be accepted if submitted. This creates a distorted view of the evidence base, as the available studies may not accurately represent all relevant research findings.

When conducting a systematic review, the goal is to aggregate all relevant data to provide a comprehensive understanding of a particular topic or intervention. However, if many studies with negative results are excluded from the review due to publication bias, the conclusions drawn may be overly optimistic or misleading. This can lead practitioners and researchers to make decisions based on incomplete or biased information, which could adversely affect clinical practice. Understanding and accounting for publication bias is therefore crucial in the systematic review process to ensure that findings are truly representative of the existing evidence.