Assessing Journal Influence: Impacted Wisdom
Authors: Robert M Frederickson, Malcolm K Brenner
Journal: Molecular Therapy (2012)

E ach year at the end of June, Thomson Reuters releases journal impact factors (IFs), a measure reflecting the average number of citations to articles published in each journal over the two previous years and generally accepted as a proxy for the relative importance of a journal among others serving a particular field. As discussed below, one can debate the wisdom of reliance on this particular citation metric, although Molecular Therapy has indeed benefited from many consecutive years of increases in the IF. Coupled with our commitment to rapid and fair review, the increases in our IF have been key to our being able to attract high-quality research papers in cell and gene therapy. It was a surprise this year to find that this upward trajectory has stalled, with our IF being trimmed slightly to 6.87, because we had expected another robust increase this year. This expectation was based on our use of Scopus (http://www.scopus.com), an independent, subscription-based bibliographic database owned by Elsevier, which has for several years proved a useful and relatively accurate tool to track our citations and estimate journal performance in this area. However, this news does have a silver lining—as counter­intuitive as it might seem, this slight reduction in our IF was associated with an increase in our ranking within the categories of “Biotechnology and Applied Microbiology” and “Genetics and Heredity,” in each case by one spot, suggesting that we are more than holding our own. How to explain an improved journal ranking but a lower IF? Perusal of the 2011 IFs of several other relevant journals provides further surprises, as it appears that a large number of journals have experienced declines, many of which are on face value difficult to understand. Indeed, one might conclude from a comparison of the IFs of journals serving investigators in gene therapy that the field is in a downward spiral (see Table 1). Of course, as readers of this journal know, this is far from the case. Looking a bit further afield, we find across-the-board decreases in the IFs of a broad spectrum of journals serving the biomedical sciences, including some very high-impact titles (see Table 2).Table 1Impact factors of selected journals in the gene therapy field20102011% ChangeMolecular Therapy7. 156. 87-3. 9Gene Therapy4. 543. 71-18. 3Human Gene Therapy4. 834. 22-12. 6Journal of Gene Medicine3. 082. 48-19. 5Cancer Gene Therapy3. 742. 80-25. 1 Open table in a new tab Table 2Impact factors of selected journals in the biosciences20102011% ChangeNature Medicine25. 4322. 46-11. 7Nature Biotechnology31. 0923. 27-25. 2Cancer Research8. 237. 86-4. 5Blood10. 569. 90-6. 3Biomaterials7. 887. 40-6. 1Nucleic Acid Therapeutics2. 992. 80-6. 4Journal of Controlled Release7. 165. 73-20Tissue Engineering4. 644. 02-13. 3Journal of Clinical Investigation14. 1513. 07-7. 6Journal of Experimental Medicine14. 7813. 85-6. 3 Open table in a new tab So what is behind this sudden drop? Unfortunately, it is difficult to know. Thomson Reuters keeps its cards close to its chest with respect to the details of IF calculation—specifically, how they handle editorial matter (such as commentaries) appearing in the “front half” of a journal, and in fact this varies from journal to journal. Although such material has generally been excluded from the denominator of the IF equation, apparently this has lately not always been the case. However, this shift seems unlikely to explain our dip this year, and further investigation is warranted. As frustrating as this situation is for a journal's editorial team, it provides an opportunity to reflect once again on the fact that the scientific establishment has come to rely so heavily on a statistic calculated by a commercial enterprise using methods that are less than fully transparent. In this day and age, surely we can, and should, do better. On the flip side, knowledge of some basic rules of IF calculation have enabled editors to take measures to promote a higher ranking, such as by publishing more reviews, promoting self-citation, and publishing a higher proportion of articles earlier in the year. None of these manipulations serves the greater good, and the literature is chock-full of repetitive and unnecessary review articles. Indeed, of the top 10 journals in the category of “Medicine, Research and Experimental,” three are review journals, whose true impact is certainly not comparable to that of the top-ranked Nature Medicine in this category. The focus at Molecular Therapy will continue to be what it always has been: to strive to publish technically excellent primary research of the greatest potential impact and interest to our broad readership. We will continue to publish reviews if and when an important topic warrants coverage, and, although difficult for a monthly title, we will also continue to provide timely editorial and commentary coverage of important publications and issues of interest to the gene and cell therapy community. Of course, like everyone else, we are forced to be mindful of the IF ranking until such time as its disproportionate impact can be lessened through the use of more transparent and less “game-able” measures of a journal's contribution to the biomedical research community. Meanwhile, the editors of Molecular Therapy encourage feedback from the community on the IF and its role in modern biomedical science.