Many indices have been developed to assess the impact of scientific publications by investigators, disciplines, and institutions. The h-index has emerged as a leading tool in the assessment of the productivity of authors. Differences in publication and citation opportunity among specialties create inappropriate conclusions when the h-index is used to compare authors across different disciplines. An alternative, the Radicchi index, hf, has been proposed to assess the impact of publications across disciplines. We curated a database of all articles published from 2002 to 2015 from the 3 highest impact factor medical journals: New England Journal of Medicine (NEJM), the Lancet, and the Journal of American Medical Association (JAMA). With this database, articles were categorized into medical subspecialties. We calculated the respective h-index and Radicchi index of each specialty. We found that the Radicchi index eliminated variability associated with publication and citation opportunity between different specialties when compared to the h-index. The Radicchi index is a useful measure of scientific impact and productivity that advances the h-index by allowing interspecialty comparisons. There remains a need to define a researcher's specialty designation especially if he/she conducts multidisciplinary research. Copyright © 2019 by the Congress of Neurological Surgeons.