Among the numerous medical journals published worldwide, it is The New England Journal of Medicine that can lay claim to having the greatest impact, at least in terms of citations.
The annual impact factors for The New England Journal of Medicine, the Lancet, Annals of Internal Medicine, The Journal of the American Medical Association, The British Medical Journal and thousands of other medical and scientific journals are calculated each year by the Institute for Scientific Information (ISI). Impact is a measure of the degree to which a journal’s articles are cited, on average, in the scientific literature. It is an approximation of a journal’s influence.
To determine a journal’s impact, ISI counts citations from all journals during a given year to the articles published in that journal over the previous two years and divides that figure by the total number of articles published in that journal in those two years. For example, the 746 total items published in The New England Journal of Medicine during 1985 and 1986 were cited 14,411 times in The 1987 Science Citation Index, which gives NEJM an impact factor of 19.3 for 1987.
The impact factors of five leading journals of general medicine for 1979, 1983, and 1987 are presented in the accompanying chart. NEJM far outpaced the other four journals each year. The Lancet consistently ranked the closest to NEJM in impact—at a level about two-thirds that of NEJM. With the exception of The British Medical Journal, which declined in impact from 3.1 to 2.8 between 1979 and 1983, the impact factors for each rose between 1979 and 1987.
NEJM’s performance is all the more impressive when its ranking among all journals tracked by ISI, not just within this group of five, is considered.
Among some 6,500 journals for which ISI calculated impact factors in 1987, NEJM ranked eighth. The Lancet ranked 19th, Annals of Internal Medicine 37th, JAMA 109th, and the British Medical Journal ranked 289th in 1987.
The conclusion reached here that NEJM and The Lancet are the highest-impact journals of general medicine agrees with the findings of an in-depth study of some 78 medical journals, which examined impact factors for 1981 and 1982 (see E. Garfield, Annals of Internal Medicine, volume 105, pages 313- 20, 1986). In that study Garfield observed, “The editorial policies of The Lancet and The New England Journal of Medicine have been highly successful and have made them the most influential journals in clinical research.”