Citation rates of Cochrane reviews versus non-Cochrane reviews

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McGowan J, Salzwedel D, Tugwell P, Grimshaw J

Background: Citation analysis of Cochrane reviews has only recently become available through sources including Thomson Scientific's ISI Science Citation Index and a new citation and abstract database called Scopus. In the near future, ISI will have enough data to generate an impact factor for the Cochrane Database of Systematic Reviews (CDSR), which will have many implications for the Collaboration and its authors.

Objectives: This abstract will investigate the epidemiology of Cochrane reviews using Scopus. It will compare and analyze the cited citation numbers of selected reviews from CDSR and from major general and specialty journals.

Methods: Scopus was searched to identify systematic reviews and meta-analyses in 2000. The citation rate of Cochrane reviews was compared to review articles in major generalist and speciality journals. The characteristics of high- and low-cited Cochrane reviews was explored.

Results: The most cited review in CDSR was 'Prophylactic corticosteroids for preterm birth' with 78 cited citations. However, many CDSR reviews had no cited citations. In the generalist journals, the most cited review from the BMJ had 345 cited citations, in JAMA it was 299 cited citations, in the Annals of Internal Medicine it was 197 cited citations, in the Lancet it was 256 cited citations and in the CMAJ: Canadian Medical Association Journal it was 19 cited citations. From the speciality journals, the American Journal of Psychiatry's most cited review was 278 cited citations. The most cited review in Pediatrics was 238 cited citations, Anesthesia and Analgesia was 157 cited citations and the Journal of Clinical Oncology was 136 cited citations.

Conclusions: CDSR is an important source of systematic review evidence but its cited reference rate was lower than in general and specialty journals. The results of the number of cited citations to Cochrane reviews will directly influence the impact factor rating of CDSR.