The pitfalls of conventional methods of screening for systematic reviews: Lessons learned

Systematic Review and Meta-Analyses (SRMAs) hold the highest rank in evidence hierarchy; however, their results are vulnerable to selective reporting and publication bias. Nonsignificant/secondary outcomes, such as adverse events or rare complications, are often omitted from the abstract due to word limits or pressure to publish. Academic databases index limited metadata but not the full-text, making outcomes that are not reported in the abstract resistant to search. This creates a modern "file drawer problem," where findings are available in full-text but remain inaccessible to search, leading to overestimated treatment effects and biased reported complication rates in SRMAs. To address this issue, this study proposed recommendations at three levels: Primary study researchers, secondary study researchers, and journals/academic databases. A collaborative effort among stakeholders is necessary to enhance the accessibility of nonsignificant outcomes through database searches, thereby reducing the risk of biased evidence that could influence clinical guidelines and patient care.