J NeuroIntervent Surg 4:395-396 doi:10.1136/neurintsurg-2012-010526
  • Editorial

JNIS: factoring the impact

  1. Robert W Tarr6
  1. 1NeuroEndovascular Program, Massachusetts General Hospital, Boston, Massachusetts, USA
  2. 2Division of Neurological Surgery, Barrow Neurological Institute, Phoenix, Arizona, USA
  3. 3Department of Neurosurgery, State University of New York at Stony Brook, Stony Brook, New York, USA
  4. 4Department of Neurological Surgery, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey, USA
  5. 5Department of Neurology, Neurosurgery and Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
  6. 6Department of Radiology, University Hospitals Case Medical Center, Ohio, USA
  1. Correspondence to Dr J A Hirsch, NeuroEndovascular Program, Massachusetts General Hospital, 55 Fruit Street, Gray 241B, Boston, MA 02114, USA; hirsch{at}
  • Accepted 30 August 2012


In this environment of information overload, establishing a journal that represents the most current advances in a fast growing field can be quite difficult. Clinicians and researchers have a veritable plethora of options, as demonstrated by the rise in national and international journals available in print or electronic version. The decision to submit a manuscript to a specific journal is met usually with two simple questions of ‘Is it indexed?’ and ‘What is the impact factor?’ Although very valid questions, one might suggest that the TRUE reason for publication is to inform as many of your colleagues as possible about what you deem to be important in an honest, concise, and effective format, thereby contributing to the repository of knowledge such that it moves the field forward.

In 2009, the Society of NeuroInterventional Surgery (SNIS) launched its flagship journal. SNIS chose the BMJ Group as its publisher, which meant that the journal had a readymade audience beyond SNIS membership as it is packaged as part of the subscription to Journal of Neurology, Neurosurgery and Psychiatry. It also provided a streamlined author submission system and a sophisticated online publication platform. The response and subsequent development has been exceptional. Three short years later, JNIS has evolved from a semi-annual publication in its first year to a quarterly in its second year. In January of 2012, JNIS moved to its current bimonthly publication schedule. JNIS is also the official journal of the Society of Vascular Interventional Neurology as well as the Neurointerventional Section of the Australian and New Zealand Society of Neuroradiology.

The journal boasts an article that has already been downloaded close to 6000 times (full text) as well as an article that has been cited 17 times in peer reviewed publications.1 ,2

JNIS publishes a broad array of material intuitively germane to various aspects of neurointervention. Most volumes feature a diverse array of cerebrovascular, spine, and other neurointervention topics.3–6 Moreover, article types range from case reports and technical notes to basic science and original clinical research.7 A robust section on socioeconomics, a particular favorite of the lead author of this article, has enjoyed over 20 unique reviews through the years.8 ,9 Multiple clinical guidelines and practice standards have been published10 Finally, commentaries on issues are published as circumstances require.11–13

In 2011, editor in chief Rob Tarr announced that JNIS had been accepted for indexing in MEDLINE and PubMed.14 This was a moment of great satisfaction for authors who contribute to JNIS. What exactly does accomplishing that milestone mean? The first clarification, implicit to the first sentence of this paragraph, is that MEDLINE and PubMed, while overlapping, are distinct entities. The Medical Literature Analysis and Retrieval System Online, commonly referred to as the National Library of Medicine (NLM), compiles MEDLINE. The database contains more than 21.6 million records from 5582 selected publications.15 ,16 Originally, the MEDLINE database covered articles published after 1965, but this was expanded, and records within the main index now date back to 1950/1951.

PubMed was first released in January 1996 as an experimental database with full access to MEDLINE. The word ‘experimental’ was dropped from the PubMed website in April 1997. In addition to MEDLINE, PubMed provides access to older references from the print version of Index Medicus, references to some journals before they were indexed in Index Medicus and MEDLINE, very recent entries to records for an article before it was indexed with medical subject headings and added to MEDLINE, and a collection of books available full text and other subsets of NLM records.17 Of note, as a result of the early indexing of JNIS, all articles dating back to the first volume were retrospectively included in both MEDLINE and PubMed. JNIS authors thus have exposure to a very wide potential audience for their work.

In year 2 of the publication of JNIS, the journal was awarded its initial impact factor. This is a term that is increasingly used, particularly among international authors. What is the impact factor?

Eugene Garfield proposed the concept of an impact factor in 1955.18 The impact factor is a product of the Institute of Scientific Information (ISI) of Philadelphia, Pennsylvania, USA. ISI was founded in 1958 to create a database listing the content of more than 4000 scientific journals published worldwide.19 The ISI is now part of the international conglomerate Thomson Reuters. Impact factors are calculated yearly for those journals that are indexed in Thomson Reuters Journal Citation Reports.

The original purpose of the ISI database was commercial; to sell listings of selected topics to researchers who wanted to stay abreast of developments in their specific areas of scientific interest. Other uses have since been found for the database—for example, the production of the impact factor. A journal's impact factor is based on two elements: the numerator, which is the number of citations in the current year to any items published in the journal in the previous 2 years; and the denominator, the number of substantive articles (source items) published in the same 2 years.

The key determinants of ‘impact’ are what might best be called the citation density and the age of the literature cited (in that 2 years represents an arbitrary time frame). Put differently, impact factor reflects the average number of citations per article and in a sense the timing of those citations. JNIS, by being awarded its initial impact factor so early in its history, saw a tripling of its denominator from 2010 to 2011. The editorial staff of JNIS are pleased to note that the 2011 Thomson Reuters impact factor is 0.923.

Perhaps mistakenly, the impact factor is being used as a means of evaluating the work of individual investigators in a given field of study.20 How so? The impact factor is sometimes used as objective evidence of the quality and importance of a faculty member's publications. Therefore, one can say that in many settings, whether appropriate or not, the impact factor is acting as a proxy for the relative importance of a journal within its field with potential impact on academic faculty, as described above. Investigators might therefore be hesitant to submit articles to journals with no or a low impact factor. English language journals, such as JNIS, benefit because international authors prefer to submit articles in English rather than their native language. This is in part a reflection of the aforementioned impact factor discussion. While those submissions do not directly affect a journal's impact factor, the journals benefit by receiving a broader array of content.

Analysis of citation patterns demonstrates review articles to be more commonly cited that original research (basic science or clinical) or case series. Given the constraints most journals (including JNIS) place on the number of references in any individual article, reviews often serve in place of earlier literature and are thus more frequently cited. Case reports are cited relatively uncommonly.

Over the past several years, we have seen a natural evolution of the content submitted to the journal. Case reports are a declining percentage of submitted content. Review articles in topics of interest have been encouraged from the first volume of JNIS. JNIS will continue to publish case reports, as the editorial staff believes that individual cases enrich the field of neurointervention. Review articles will continue to be encouraged, and outstanding original research will continue to be coveted. At times, the focused review required for neurointervention may not lend itself to frequent citation, nonetheless, topical interest and value to the neurointerventional reader rather than likelihood of future citation will guide publication.

What does all of this mean for the JNIS? We believe the impact factor to be a meaningful metric for our consideration. While that metric informs, it does not dictate decisions regarding the direction of the journal.

Our goal is clear: share in our knowledge; educate our colleagues in all fields of medicine; and invigorate discussion of the many exciting and sometimes difficult issues that surround us. That is what we do. That is the Journal of NeuroInterventional Surgery.

It has been an exciting few years since the inception of the JNIS. We look forward to the opportunity to continue to impact the field of neurointerventional surgery into the future.


  • Contributors All authors contributed to this manuscript.

  • Competing interests None.

  • Provenance and peer review Commissioned; not externally peer reviewed.



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