Retractions in the medical literature: how can patients be protected from risk?

BACKGROUND: Medical research so flawed as to be retracted may put patients at risk by influencing treatments. OBJECTIVE: To explore hypotheses that more patients are put at risk if a retracted paper appears in a journal with a high impact factor (IF) so that the paper is widely read; is written by a 'repeat offender' author who has produced other retracted research; or is a clinical trial. METHODS: English language papers (n=788) retracted from the PubMed database between 2000 and 2010 were evaluated. Only those papers retracting research with humans or freshly derived human material were included; 180 retracted primary papers (22.8%) met inclusion criteria. Subjects enrolled and patients treated were tallied, both in the retracted primary studies and in 851 secondary studies that cited a retracted primary paper. RESULTS: Retracted papers published in high-IF journals were cited more often (p=0.0004) than those in low-IF journals, but there was no difference between high- and low-IF papers in subjects enrolled or patients treated. Retracted papers published by 'repeat offender' authors did not enrol more subjects or treat more patients than papers by one-time offenders, nor was there a difference in number of citations. However, retracted clinical trials treated more patients (p=0.0002) and inspired secondary studies that put more patients at risk (p=0.0019) than did other kinds of medical research. CONCLUSIONS: If the goal is to minimise risk to patients, the appropriate focus is on clinical trials. Clinical trials form the foundation of evidence-based medicine; hence, the integrity of clinical trials must be protected.