Beyond retractions: tackling the contamination chain of flawed evidence

Xu and colleagues quantify the impact of retracted clinical trials on systematic reviews and clinical practice guidelines.1 They found that removing retracted trials altered statistical significance in 16% of meta-analyses and reversed effect direction in 8.4%, with evidence from these distorted systematic reviews cited in 157 clinical practice guidelines. These findings show how flawed data propagate through a “contamination chain” in the biomedical evidence ecosystem. They also highlight a critical gap: the need to tackle contamination beyond formally retracted studies, as retractions are only the tip of a much larger iceberg threatening evidence integrity.Retractions can take years, allowing unchallenged contamination during this period.2 Even after retraction, contamination persists: citation rates decline only 6.9% annually, with half or more future citations still accepting original claims.3 Meanwhile, unretracted but low quality or ethically compromised studies continue to threaten evidence based medicine. Expressions of concern are inconsistently applied and seldom integrated into citation…