More consideration is needed for retracted non-Cochrane systematic reviews in medicine: a systematic review

•An increasing number of non-Cochrane systematic reviews in medicine are being retracted.•The most common reasons for retraction are fraudulent peer-review and unreliable data.•In most cases the systematic review was retracted more than a year after publication.•COPE guidelines on retraction notice were not adhered to in some aspects. To analyze the retraction status and reasons of non-Cochrane systematic reviews (SRs) in medicine. MEDLINE, Embase, Retraction Watch Database and Google Scholar were systematically searched to find all retracted non-Cochrane SRs. Of 159 non-Cochrane SRs in medicine retracted between 2004 and 2020, more than 70% were led by authors from China and affiliated with hospitals. The largest proportion of retraction notices were issued by the publisher and editor(s) jointly. Fraudulent peer-review was the most common reason for retraction, followed by unreliable data meaning errors in study selection or data analysis. The median time between publication and retraction was 14 months, and SRs retracted due to research misconduct took longer to retract than honest error. The total number of retracted SRs is increasing worldwide, in particular in China. The most common reasons for retraction are fraudulent peer-review and unreliable data, and in most cases the SR is retracted more than a year after publication. Better systems of ethical oversight and culture to improve the process of peer review and adherence to the COPE retraction guidance are needed, and authors should strengthen their skills in SR methodology.