Use of inactive Cochrane reviews in academia: A citation analysis

The Cochrane Database of Systematic Reviews is internationally recognized as one of the best sources of evidence within medical research. Nevertheless, a considerable amount of Cochrane reviews in the Cochrane Database of Systematic Reviews (CDSR) have not been updated for more than 5.5 years and are therefore considered inactive. This study's aim was to evaluate if these are still used in academia. The study included 7,729 Cochrane reviews from the CDSR. Their Digital Object Identifiers (DOIs) were linked with citation data from the search engine The Lens. The citation pattern of 3,735 inactive reviews in the CDSR were analyzed and the results were adjusted for inflation in citation. A subgroup analysis of citing motives was performed for the most recent citations of the 20 most outdated reviews. In 2020, 41% of all citations of Cochrane reviews, were of reviews that had not been updated for more than 5.5. years. 5 years after last update, Cochrane reviews were on average cited 8.6 times per year. Twenty-five percent of Cochrane reviews were still cited 10 years after last update and were on average cited 4.3 times in the 10th year. None of the most recent citations of the 20 most outdated reviews indicated directly that the review was out of date. Cochrane reviews continued to be cited even though they were not being updated. This could pose a problem if they do not represent the most up-to-date evidence, as it may lead to the distribution of outdated evidence or misinformation.