Objective: To determine whether availability of journals on MEDLINE as FUTON (full text on the Net) affects their impact factor.
Material and methods: A comprehensive search identified 324 cardiology, nephrology, and rheumatology/immunology journals on-line until May 2003. The status of these journals was ascertained in MEDLINE as having FUTON, abstracts only, and NAA (no abstract available). Impact factors for all available journals from the Institute for Scientific Information (ISI) were abstracted.
Results: Of the 324 Journals, 124 (38.3%) were FUTON, 138 (42.6%) had abstracts only, and 62 (19.1%) had NAA. The mean (+/-SEM) impact factor was 3.24 (+/-0.32), 1.64 (+/-0.30), and 0.14 (+/-0.45), respectively. Of the 324 current journals, 159 existed in both the pre- and the post-Internet era. An analysis of the change (ie, delta) in impact factor from the pre- to post-Internet era revealed a trend between journals with FUTON and abstracts only (P=.17, Wilcoxon rank sum test). Similar analyses of the delta of cardiology journals revealed a statistically significant difference between Journals with FUTON and abstracts only (P=.04, Wilcoxon rank sum test).
Conclusion: FUTON bias is the tendency to peruse what is more readily available. This is the first study to show that on-line availability of medical literature may increase the impact factor and that such increase tends to be greater in FUTON journals. Failure to consider this bias may affect a journal's impact factor. Also, it could limit consideration of medical literature by ignoring relevant NAA articles and thereby influence medical education akin to publication or language bias.