Kovacic N and Misak A. "Author self-citation in medical literature" Canadian Medical Association Journal, 170(13):1929-1930,

Eugene Garfield garfield at CODEX.CIS.UPENN.EDU
Fri May 6 16:54:35 EDT 2005

Natasa Kovacic : natasa at mef.hr

CMAJ • June 22, 2004; 170 (13). doi:10.1503/cmaj.1040513

Full text :

TITLE   : Author self-citation in medical literature

AUTHOR  : Natasa Kovacic and Aleksandra Misak

SOURCE  : Canadian Medical Association Journal, 170(13):1929-1930,
          June 22 2004

Cited References: 6
   GAMI AS, 2004, CAN MED ASSOC J, V170, P1925
   GARFIELD E, 1999, CAN MED ASSOC J, V161, P979
   KOVACIC N, 2004, CROAT MED J, V45, P18
   SEGLEN PO, 1997, BRIT MED J, V314, P498

Addresses: Kovacic N (reprint author), Univ Zagreb, Sch Med, Dept Anat,
Salata 3B, Zagreb, 10000 Croatia
Univ Zagreb, Sch Med, Dept Anat, Zagreb, 10000 Croatia

E-mail Addresses: natasa at mef.hr


IDS Number: 833LL

ISSN: 0820-3946
>From the Department of Anatomy (Kovacic) and the Croatian Medical Journal
(both authors), Zagreb University School of Medicine, Zagreb, Croatia.

Correspondence to: Dr. Natasa Kovacic, Department of Anatomy, Zagreb
University School of Medicine, Salata 3B, 10000 Zagreb, Croatia; fax
+385-1-4590-222; natasa at mef.hr


In this issue Gami and colleagues1 report on their investigation of author
self-citation (the practice of citing one's previous publications in a new
publication) as a possible source of bias in bibliometric assessment of the
importance of a journal or an auth

or. Focusing on articles about diabetes mellitus as representative of the
general clinical medical literature, they found that nearly one-fifth of all
citations per year were author self-citations. They found no association
between methodologic quality of articles and frequency of author
self-citation. Compared with review articles, original articles had double
the proportion of author self-citations. Articles published in highly cited
journals had a smaller proportion of author self-citations than articles
published in less-cited journals.

Citing is an established way for authors to declare their sources of
information and politely recognize someone's intellectual property. The
importance of an article, author or journal can be estimated through the
number of citations each acquires. For journals, such a number is
transformed into the impact factor, which approximates the frequency with
which articles have been cited in the 2 years after publication.2 However
imperfect and potentially unfair it may be, the impact factor is the best
measure of a journal's quality we have today.3,4 But what can the proportion
of a certain type of citation, such as author self-citation, tell us about a
given article, author or journal?

A high rate of author self-citation may result from the fact that authors
stick to their specific field of research and, naturally, rely on their
previous results. To reduce article length, authors may cite previous work
in which, for example, the same methods are described. It is also possible,
however, that they overestimate the importance of their earlier research
compared with other work they could have cited, or that they want to
increase artificially the number of citations to their own work, thus
distorting the perception of its importance. Institutional criteria for
academic advancement take into account the total number of publications by
the author and sometimes the total number of citations of that author's
work. The latter might provide incentive for authors to self-cite, but
self-citation does not really reflect the visibility and quality of their
work. Finally, authors who publish a lot have more opportunities to cite
their own previous work, which is why author self-citation rates may
correlate with authors' publishing productivity. For these reasons, it is
impossible to determine the level of authors' integrity with regard to

Gami and colleagues' finding that review articles had a smaller proportion
of self-citations than original scientific articles1 may be explained by the
fact that review articles are more widely read and therefore receive more
citations in general.

Both journal self-citation (when articles in a journal cite previous
articles in the same journal) and author self-citation may influence the
journal's impact factor.5 From the e-table presented by Gami and colleagues1
it is clear that author self-citations accounted for a negligible proportion
of citations in the high-impact journals and, therefore, would not
substantially distort the impact factor of those journals. From the same
data, one can also presume that there is an inverse correlation between the
proportion of author self-citations and the impact factor of a journal. Our
analysis of citations of the Croatian Medical Journal indicated that an
increase in the absolute number of citations was indeed followed by a
decrease in the proportion of both author and journal self-citations.6 The
decrease in author self-citations could have been due to widening of the
author pool (a result of better international visibility of the journal) or
to increased quality of articles (which would attract independent
citations), or it may simply have been mathematical, self-citations having
been "diluted" by the higher number of independent citations. The decrease
in the proportion of journal self-citations probably reflected the journal's
increased visibility.6 Although a high proportion of journal self-citations
may indeed increase the impact factor of a journal, in small journals this
increase is illusory: it does not reflect an increase in international
visibility, since the flow of information is limited mostly to the pool of
the journal's authors and readers.

Whatever the reason, a high proportion of self-citations per article cannot
be taken solely as a reflection of the limited quality of a journal: some
journals have a narrower scope, either thematically or geographically, and
consequently a smaller pool of authors. Journals that are both influential
and important are characterized by a high impact factor, the publication of
"milestone" articles and prestigious authors. Journals that make an
important but less influential contribution typically publish in a fruitful
area of research occupied by fewer investigators who are nonetheless highly
productive and well cited. Journals with limited influence and importance
publish in a highly specific area, have a small circulation, a high degree
of overlap between the readership and the author pool, and receive few
citations. For almost identical reasons, an article or author with a high
proportion of self-citations cannot be accused of lower research quality or
integrity. This is supported by Gami and colleagues' finding that
"self-citations had little relation with the quality of an article."1 The
total number of citations also has to be taken into account. A highly cited
article, author or journal with a substantial proportion of self-citations
(considering the total citation number) is more visible than the rarely
cited without any self-citations.

In this way, this noteworthy article1 opens the question of the "morally
allowable" proportion of self-citations and offers an elegant and workable
model for the pertinent research.

ß See related article page 1925


This article has been peer reviewed.

Contributors: Both authors contributed substantially to all phases of
manuscript preparation and approved the version to be published.

Competing interests: None declared.


1. Gami AS, Montori VM, Wilczynski NL, Haynes RB. Author self-citation in
the diabetes literature. CMAJ 2004;170(13):1925-7.[Abstract/Free Full Text]

2. Garfield E. Journal impact factor: a brief review [editorial]. CMAJ 1999;
161: 979-80.[Free Full Text]

3. Christopher MM. The impact factor: getting a grip. Vet Clin Pathol 2003;
32: 98-100.[Medline]

4. Seglen PO. Why the impact factor of journals should not be used for
evaluating research. BMJ 1997;314:498-502.[Medline]

5. Fassoulaki A, Paraskeva A, Papilas K, Karabinis G. Self-citations in six
anaesthesia journals and their significance in determining the impact
factor. Br J Anaesth 2000;84:266-9.[Abstract/Free Full Text]

6. Kovacic N, Misak A. What can be learned from impact factor of Croatian
Medical Journal, 1994-2003? Croat Med J 2004;45:18-24.[Medline]

Related Article

Author self-citation in the diabetes literature
    Apoor S. Gami, Victor M. Montori, Nancy L. Wilczynski, and R. Brian Haynes
    Can. Med. Assoc. J. 2004 170: 1925-1927. [Abstract] [Full Text]

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