Background: The Impact Factor of the Cochrane Database of Systematic Reviews (CDSR) is calculated and published as part of the Journal Citation Reports (JCR) by a commercial company, Thomson Reuters, each year in June. From 2007 to 2010, the Impact Factor of the CDSR increased by an average of 10% annually. For the first time in 2011, the CDSR Impact Factor decreased. The CDSR is currently in the top 10 of the Medicine, General & Internal category of the JCR.

Objectives: To establish the reason(s) why the Impact Factor for the CDSR decreased in 2011 by analysing the citation data from 2010 to 2011 and the 2012 data when available, and to look for methods to minimize the risks of this becoming a trend.

Methods: Citation data taken from the ISI Web of Science covering the years 2009–2012 will be analysed using a macro created in Microsoft Excel in order to identify the factors contributing to an increase or decrease in the CDSR Impact Factor.

Results: Is the CDSR Impact Factor reliant on a small number of highly cited articles? Has there been a large increase in the number of citable items published? Are more reviews being published that are not cited? Which subject areas, individual articles and Review Groups have contributed most to the Impact Factor of the CDSR?

Conclusions: Conclusions will be drawn from the analysis once the data is made available from Thomson Reuters in June 2013.