Discussion

Analysis of the retractions on Medline suggests that journals' retraction practices are not uniform. Detailed analysis of the retraction texts also revealed that reasons for retraction are not always clearly stated. This is unfortunate, since retractions may be triggered both by genuine mistakes and by misconduct. It is therefore important to indicate the reason for the retraction so that authors who have acted responsibly in alerting the journal to problems with their work are not stigmatised along with those who have committed misconduct. This is emphasised in the COPE retraction guidelines4 (published in 2009 after this study was completed) and has been recommended by the International Committee of Medical Journal Editors since at least 1997. However, we found several, quite recent, examples of retraction notices that failed to state the reason for retraction, including six published in 2006 alone.

Cases presented to COPE indicate that some editors believe retractions can only be made by the original authors. This can cause problems if some or all of the authors do not agree or cooperate with a retraction. Our survey clearly shows that retractions can be issued by journal editors, with or without the cooperation of the authors. In two instances, we found retractions that had been issued by the authors' institution following inquiries into research misconduct. These provide an excellent example of institutions taking their responsibility for research integrity seriously and we suggest this practice should be encouraged.

Two previous studies on this topic have been published. Budd et al analysed 235 Medline retractions issued between 1966 and 1997.5 They found 81% of retractions were issued by authors (compared with 63% in our sample). They also found that 9% of retraction notices did not state the reason for retraction clearly (while we found 5%). They also examined whether retracted articles were cited after retraction and found 2034 citations to the 235 articles in their sample. Further analysis of these citations found that most were positive (ie, not criticising the retracted paper or mentioning the fact that it had been retracted).6

Nath et al examined retractions listed in Medline between 1982 and 2002 and categorised the reasons for retraction as either misconduct or unintentional errors.7 They found 27% were retracted because of misconduct and 62% because of errors. Given the similarity of sample base for this study and ours, the similarity of findings is reassuring (we found 28% of retractions were due to misconduct) but our categorisation provided more detail than previous studies.

Anecdotal evidence from COPE Forum meetings, and analysis of some high-profile cases, suggests that journals are not consistent in their retraction practices.2 3 Liu has noted that the highest impact journals are also ‘world leaders in publishing retractions’ calculating that Science, Nature, PNAS and Cell contributed 9% of all Medline retractions in the early 2000s.8 Liu suggests that this may be because these journal publish controversial research, but it may also be because these well-staffed journals are more diligent in pursuing or responding to misconduct allegations and errors than less well-resourced journals. The qualitative arm of our study (to be published separately) aimed to address reasons that might prevent editors from issuing retractions.

Inconsistency in retracting articles may be due to lack of external guidance (the COPE guidelines were only published in late 2009) or lack of a clear internal (ie, journal or publisher) policies. Atlas reviewed the instructions to authors of 122 ‘major biomedical journals’ in 2003 and found that only 18% reported having a policy on retractions.9 However, editors' uncertainty about how and when to retract articles may also reflect the fact that the research community does not have agreed norms about responses to research misconduct. Korenman et al surveyed 606 scientists receiving US National Science Foundation grants and 91 representatives of research institutions with responsibility for the ethical conduct of research (listed by the US Office of Research Integrity) about whether certain acts were unethical and, if so, the appropriate response and punishment for the act.10 They found that the scientists were more likely to suggest retraction as an appropriate response than the institutional representatives. They suggest that this may be because the institutional representatives believe ‘their main role is to protect, preserve and enhance the institution’ so they favour ‘sanctions aimed at punishment and deterrence’ while ‘damage to the social fabric of science may be a lesser consideration’. Whereas, for scientists, Korenman et al suggest, the ‘integrity of the scientific community is essential’.

Another reason why editors may be uncertain what to do is that they may be faced with inconclusive evidence.11 Parrish noted that ‘substantial delays are endemic in notifying the journal… about allegations and findings of scientific misconduct’.3 In a later study, she examined the use of ‘expressions of concern’ and concluded that these may be useful ‘for ensuring the integrity of the research record during the sometimes lengthy period that research misconduct investigations can take’.12 The COPE retraction guidelines recommend that editors should consider issuing an expression of concern if they receive inconclusive evidence of misconduct, the authors' institution refuses to investigate the case, they believe an investigation will not be impartial, or a judgement will not be available for some time.4 Medline does not tag expressions of concern so we were unable to include them in this study.

This study was used to inform the development of the COPE retraction guidelines, in addition to consideration of cases presented at COPE Forum meetings.4 In our study, for example, although we did not record the proportion of retraction notices that were freely available to all readers (ie, not only to journal subscribers), we were surprised how hard some retraction notices were to find. The COPE guidelines therefore recommend that retraction notices should ‘be freely available to all readers (ie, not behind access barriers or available only to subscribers)’. Cases presented at COPE Forum meetings suggested that some editors were not clear about the primary function of retractions, so the guidelines state that ‘The main purpose of retractions is to correct the literature and ensure its integrity rather than to punish authors who misbehave’. The COPE guidelines also emphasise the fact that retractions may be needed in cases of misconduct or of genuine error and therefore stress the importance of clearly stating the reason for each retraction.

We conclude that journals indexed in Medline display inconsistency in their practices regarding retractions but there has been a marked increase in the number of articles being retracted. Despite published guidance, some journals continue to retract articles without clearly stating the reason for the retraction: this is regrettable. While we recognise that variations in journals' practices may reflect genuine differences in belief about the correct approach, we suggest that a more uniform approach is desirable to safeguard the reliability of the published research record and to ensure that authors are not unfairly stigmatised by unwarranted retractions. We therefore recommend that editors follow the COPE retraction guidelines which were based on the experience of COPE members and the findings of this study.4