Journal accused of manipulating impact factor

BMJ 1997; 314 doi: (Published 15 February 1997) Cite this as: BMJ 1997;314:461
  1. Richard Smith
  1. BMJ

    The journal Leukemia, which is owned by Macmillan magazines, has been accused of trying to manipulate its impact factor, the measure used to rank the importance of scientific journals. The accusation comes from Terry Hamblin, consultant haematologist at the Royal Bournemouth Hospital and editor of Leukemia Research, a rival to Leukemia.

    Dr Hamblin has sent the BMJ a copy of a letter received by authors who had submitted a paper to Leukemia in October 1996 asking them to increase the number of references to papers published in Leukemia. This would increase the journal's impact factor, which is calculated by dividing the number of citations of papers in the journal by the number of papers that could be cited. The impact factor has become much more important in recent years because many countries consider the impact factors of the journals in which researchers publish when judging the researchers and making decisions about future funding (p 498).

    The letter from Leukemia said: “Manuscripts that have been published in Leukemia are too frequently ignored in the reference list of newly submitted manuscripts, even though they may be extremely relevant. As we all know, the scientific community can suffer from selective memory when giving credit to colleagues. While we have little power over other journals, we can at least start by giving you and others proper credit in Leukemia. We have noticed that you cite Leukemia [once in 42 references]. Consequently, we kindly ask you to add references of articles published in Leukemia to your present article.”

    This is a blatant attempt to increase the journal's impact factor,” said Dr Hamblin. “I accept that authors sometimes do not cite relevant papers, but I have never encountered a journal that specifically requested an increase in the number of times that journal is cited in the bibliography.”

    Dr Nicole Muller-Bérat, the editor of Leukemia, denies that the journal is trying to manipulate its impact factor. “We introduced the policy of asking people to cite Leukemia for two main reasons. Firstly, we have received, and published, letters from authors saying that papers we have published have neglected to cite important papers published in Leukemia. Secondly, our reviewers remember important papers published in major journals like Blood, Cell, and the British Journal of Haematology, but they forget about important papers published in Leukemia“.

    Dr Muller-Bérat believes that Dr Hamblin is motivated to make his accusation by professional jealousy. She founded Leukemia Research, the journal he edits, with her husband, but he became the editor in 1986. Since then the impact factor has fallen from 2.7 to 1.179. She and her husband also founded Leukemia in 1987, and by 1991 it had an impact factor of 3.059. Following changes in the editorial team, the impact factor fell to 1.7 but has now risen to 2.35.

    David Pendlebury, an analyst at the Institute of Scientific Information in Philadelphia, which calculates journals' impact factors, said: “We have never heard of a case like this before. It is a distortion of the scientific process.” Richard Horton, editor of the Lancet, said: “Given the importance attached to impact factors this manipulation seems an appalling lapse of editorial judgment.”