From the Department of Medicine, University Hospital St Radboud, Nijmegen, the Netherlands.
Context.— The number of authors per article has increased markedly in recent years.
Little is known about the hierarchical order of authorship and its change
Objective.— To assess the change in number and profile of authors of original articles
published over a 20-year period in BMJ . It was hypothesized
that the number of authors increased over this 20-year period and that it
was the senior scientists who benefited most.
Design.— Comparative descriptive analysis of the number and academic rank of
authors who published original articles in BMJ volumes
270 (1975), 280 (1980), 290 (1985), 300 (1990), and 310 (1995).
Main Outcome Measures.— The specific academic rank, order, and number of authors for each original
article. Eight categories of authorship were distinguished as follows: 1,
professor; 2, department chairperson; 3, consultant; 4, senior registrar;
5, lecturer and/or registrar; 6, medical student; 7, house officer; and 8,
Results.— The number of original articles published per year decreased from 262
(1975) to 125 (1995). The mean number (SD) of authors per article increased
steadily from 3.21 (SD, 1.89) (1975) to 4.46 (SD, 2.04) (1995). Most authors
belonged to category 3, and its proportion varied from 24.7% (1975) to 22.6%
(1995), while category 1 grew from 13.2% to 20.3%. Category 5 authorship dropped
from 24.3% (1975) to 15.8% (1995). With regard to first authorship, category
1 more than doubled from 8.0% (1975) to 16.8% (1995) compared with category
5 whose proportion decreased from 34.0% to 24.8%. Most last authors were from
category 1, 20.4% (1975), growing to 29.0% (1995).
Conclusion.— Over the last 20 years the number of BMJ authors
of original articles increased, mainly because of the rise of authorship among
professors and department chairpersons.
IN RECENT YEARS, the concept of authorship has been the subject of great
debate, mainly because of the proliferation of authors over the years.1 A survey of radiology journals showed a doubling of
authorship: from 2.2 authors per article (1966) to 4.4 (1991),2
a trend most obvious in clinical medicine.3,4
The increase of authorship has been documented before, but it is unclear
which author category (eg, junior or senior scientists) took most advantage
from this proliferation. It might be speculated that because of seniority,
senior scientists are better able to influence the decision on authorship.
This view is supported by complaints that senior scientists sign for authorship
at the expense of junior researchers.5,6
There are further indications that authorship is granted to chairpersons of
departments as a matter of convention or that senior authors are listed just
to boost the paper.7 This survey was conducted
to assess the clinical or teaching appointment of individual authors over
a 20-year period for BMJ . It was hypothesized that
in this period authorship would increase with senior authors benefiting most.
The study sample was retrieved from BMJ selecting
the following volumes (year): 270 (1975), 280 (1980), 290 (1985), 300 (1990),
and 310 (1995) and consisted of all individual original articles, including
"Papers," "Originals," and "Short Reports" (volume 270 through 290), and "Papers"
(volume 300 and 310). Articles reported on behalf of a group (n=16) were excluded
from the study. All individual original articles were examined and information
was obtained on (1) number of authors, (2) country of origin for the first
author, (3) specific listed clinical or research appointment for each separate
author, (4) order of authorship, and (5) separate indication of the author's
profession as statistician. The appointments of the authors were divided into
8 categories: 1, professor, assistant professor, associate professor, or reader;
2, department chairperson or director; 3, consultant or senior lecturer; 4,
senior registrar or fellow; 5, lecturer, registrar, senior research fellow,
research fellow, or research registrar; 6, medical student or research assistant/associate;
7, house officer, senior house officer, or resident; and 8, miscellaneous.
If multiple appointments were mentioned, only the first was included.
Statistical Analysis. The χ2 test was used to assess differences between 1990
and 1995. The 1-way analysis of variance was used to detect significant changes
in the mean number of authors per article over time. Data are expressed as
mean (SD) or as a percentage.
In the time span studied, the number of original articles decreased.
The mean number of authors per article significantly increased and this was
most notable for the last 5 years (P<.001). In
the same period, the number of articles with 6 or more authors increased steadily
(Figure 1), and single authorship
was virtually absent (Table 1).
There was a steady increase of input by statisticians (Table 1). During the 20 years studied, the contribution from British
institutions remained around 77%.
All Authors. Most BMJ authors were from category 3, and
there was little change over the study period (Table 2). In the last 5 years, there was a large rise of category
1 authors, which coincided with a similar increase of the mean number of authors
per article (P=.003) (Figure 1). In contrast, category 5 authorship decreased in that
same period (P=.002). In 1995, almost 60% of all
authors stemmed from 3 categories (categories 1, 3, and 5).
First Authors. There was a doubling for first authors from category 1 in the last 5
years (P=.03) (Table 2). This contrasted to category 5 whose proportion decreased
by three fourths in the same period. However, even in 1995, most first authors
were from category 5. There was a decrease of category 3 first authors for
1975 to 1990, but this recovered slightly in 1995.
Last Author. As might be expected, most last authors were of senior level: category
1 accounted for one fifth of all last authors in 1975 and its proportion grew
approximately one third in 1995 (P<.001) (Table 2). Category 2 last authorship did
not change over time. As was the case with first authorship, category 3 contribution
to last authorship initially rose but later fell (P=.005).
Two thirds of last authors were from categories 1, 2, or 3. In 1995, virtually
nobody from category 4 was listed as last author.
This study clearly documents the increase of authorship8:
each BMJ article gained on average 1.25 authors over
the last 2 decades, and multiauthor articles have become common. Interestingly,
the largest increase occurred in the last 5 years, during which formal authorship
criteria were included in the Instructions to Authors. In addition, a considerable
shift of authorship was noted: senior researchers, such as professors and
chairpersons, were increasingly included as authors. For example, in the last
5 years, the mean number of authors grew by about 50%, but at the same time
75% more professors were added to the authorship listing. By contrast, the
proportion of all other, more junior, authors such as lecturers decreased.
There was not only a mere increase of authorship but also a shift in
the authorship order. Senior authors (professors and chairpersons) have moved
to first authorship at the cost of other categories like consultants and lecturers.
As might be expected, the last author position is taken by the senior member
of the research team and this position was secured over time.9
How can we explain these results? The increase of the absolute number
of senior positions in research units during this period might have exceeded
that of junior posts. On the other hand, senior scientists might have become
more active in initiating and guiding research. Indeed, a study executed in
the 1980s among chairpersons of various medical departments showed that those
who had been head chairperson for less than 10 years increased their number
of articles, last author articles, and coauthors per article over time.10 This finding suggests that a change in hierarchical
status influences authorship patterns. Senior scientists are under great pressure
to publish: a number of British departments insist that supervisors are included
as author on their students' papers.11 This
practice might lead to gift authorship: granting of authorship to those who
did not make any intellectual effort for the study. A recent study showed
that the contribution of individual authors was lowest in multiauthor papers.12 Another survey detected that 26% of authors to these
papers did not contribute significantly to the work. One third of these authors
were heads of laboratories, groups, divisions, or departments.13
These data suggest that authorship is not always a representative measure
of actual intellectual achievements.
Changes in the editorial policy of BMJ might
account for the results; a different editorial policy might lead to acceptance
of papers by professors over those written by junior authors. There was a
change in editor in May 1991 and, interestingly, the largest shift of authorship
profile took place between 1990 and 1995. The BMJ
attracts different papers now than in 1975; it publishes more epidemiological
studies. Initiation, execution, and reporting of epidemiological studies requires
seniority, hence, the shift to more senior authors. Further, these large studies
need statistical input and this survey documents the increase of statisticians
as authors. Besides, statisticians have argued that they should be included
as coauthors.14 This is understandable given
the high error rate against statistical methods in medical articles.15
This study must be interpreted with several limitations. The data are
derived from BMJ, and it can be argued that the results
are only applicable to the local British situation. The specific author categories
are British, but corresponding ranks do exist elsewhere. Because 5-year intervals
were chosen, sampling error may influence the results. Despite these restrictions,
the data suggest an increase of authorship associated with a proliferation
of senior authors.
Drenth JPH. Multiple AuthorshipThe Contribution of Senior Authors. JAMA. 1998;280(3):219-221. doi:10.1001/jama.280.3.219