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Military medical personnel, like all other physician specialists, face the challenge of keeping updated with developments in their field of expertise, in view of the great amount of new medical information published in the literature. The availability of the Internet has triggered tremendous changes in publication characteristics, and in some fields, the number of publications has increased substantially. The emergence of electronic open access journals and the improvement in Web search engines has triggered a significant change in the publication processes and in accessibility of information.
The objective of this study was to characterize the temporal trends in the number and types of publications in military medicine in the medical literature.
We searched all PubMed-registered publications from January 1, 1990 to December 31, 2010 using the keywords “military” or “army”. We used the publication tag in PubMed to identify and examine major publication types. The trends were tested using the Mann-Kendall test for trend.
Our search yielded 44,443 publications in military medicine during the evaluation period. Overall, the number of publications showed two distinct phases over time: (1) a moderate increase from 1990 to 2001 with a mean annual increase of 2.78% (
We conclude that over the past twenty years, scholarly work in the field of military medicine has shown a significant increase in volume, particularly among high quality publication types. However, practice guidelines remain rare, and meta-analyses are still limited in number.
At the end of the first decade of the twenty-first century, military medicine continues the evolving process of broadening its range, responsibilities, and resources, in combination with continued progress in developing unique skills and knowledge. Advances in health care, for instance, in the field of trauma care, often guide military medicine. Hence, military medical personnel, like other physician specialists, face the challenge of keeping updated with developments in their field of expertise. This is especially challenging in view of the great amount of new medical information regularly published in the literature [
Military medicine is closely interwoven with a variety of medical specialties. Innovations in medical knowledge require implementation in military medicine, and medical challenges seen in the military environment may trigger further clinical research and development for general medicine.
Several search engines have been developed which allow easy access to relevant medical information. The National Library of Medicine offers PubMed as a free service that enables convenient searches of medical publications. PubMed is more than a search engine; it is also an extremely large, free, and highly reputable database of the biomedical and health care literature. PubMed uses a defined system of categorization of medical publications. Among these publication types, one can find clinical trials, reviews, editorials, meta-analyses, randomized controlled trials (RCTs), and practice guidelines, as well as additional publication types.
The aim of this study was to characterize the overall and publication type-specific temporal trends of scientific publications in military medicine over the last two decades.
We used the PubMed search engine on June 5, 2012 to examine all of the articles indexed from January 1, 1990, through December 31, 2010, searching for publications in the field of military medicine. A military medicine publication was defined as an article published in a military medicine journal, or, if the subjects/participants were soldiers/veterans or army personnel, or, if the author affiliation was a military hospital or army medical institute. Our search algorithm was based on several exploratory terms including "military", "army", "combat", "war", "soldier", "battle", "terror", and "weapon". These terms were highly sensitive, but nonspecific, and returned articles outside of the intended field of military medicine. We attempted several keyword combinations, which we validated by examining the abstracts of the first ten articles in each type for a single publication year (2010). Upon completion of this process, the final keyword terms selected were "military OR army". An alternative search strategy we considered, involved using medical subject headings (MeSH) terms. MeSH is the National Library of Medicine's controlled vocabulary thesaurus, which consists of sets of terms in a hierarchical structure that permits searching at various levels of specificity to select specific fields of medicine [
The statistical analysis was performed using the WinPepi software (version 11.25, October 2012) [
During the 21 year period, PubMed reported 44,443 publications related to military medicine, with a mean of 2116.3 publications per year (SD 958.6). We discerned two distinct phases, with a shift in the character of the trends over time up to and after 2001. From 1990-2001, we identified a linear progression with a moderate slope, indicating a mean annual increase of 2.78% in the publication volume, increasing from 1238 in 1990 to 1658 in 2001. From 2002 to 2010, there was a substantial change in the trend, with an increased slope (
Total number of publications in military medicine by year of publication.
The subset of high quality publications (RCT, systematic review, and meta-analyses) represented 5.45% (2421/44,443) of all the publications during the overall evaluation period, with a mean of 4.86, SD 1.48% annually (
Most of the publication types showed a moderate mean annual incremental change in the early phase, and a steep increase in the later phase. The most common publication type in the lower quality category was the case report (15.01%, 6671/44,443). Case reports were published during the early phase at a gradually decreasing annual rate of 2.02%. In the later phase, however, this trend was reversed, and the publication of this article type proceeded at an annual rate of 10.89%. During the same time periods, the annual rate of increase for clinical trials nearly doubled from 7.05% in the early phase to 13.02% in the later phase. The trends for editorials and practice guidelines (1.02% and 0.06% respectively) were much less stable, owing mostly to the small absolute number of these article types.
Editorials and case reports showed a linear decrease in publication volume during the early phase, but still increased during the later phase.
The mean number of annual publications, mean annual incremental change and
Publication type | All years, 1990-2010 | Phase 1, 1990-2001 | Phase 2, 2002-2010 | ||||||||
n (%) | Mean annual publications (SD) | Mean annual % incremental change | Mean annual % incremental change |
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Mean annual % incremental change |
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All articles | 44,443 (100) | 2116.3 (958.6) | 6.83 | 2.78 | .79 | <.002 | 11.20 | .96 | <.002 | ||
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2421 (5.4) | 115.3 (94.4) | 14.20 | 10.01 | .80 | <.002 | 20.66 | .88 | <.002 | |
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RCT | 1472 (3.3) | 70.1 (38.0) | 10.29 | 6.87 | .54 | <.02 | 16.95 | .91 | <.002 |
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Systematic review | 736 (1.7) | 35.1 (41.8) | 29.90 | 30.70 | .69 | <.002 | 27.18 | .84 | <.002 |
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Meta- analyses | 213 (0.5) | 10.1 (16.6) | 67.78 | 75.0 | .52 | <.02 | 65.0 | .75 | <.02 |
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17,960 (40.4) | 855.2 (307.9) | 5.33 | 1.42 | .39 | <.05 | 10.54 | .99 | <.002 | |
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Case reports | 6671 (15.0) | 317.7 (113.9) | 4.58 | -2.02 | .51 | <.02 | 10.89 | .98 | <.002 |
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Reviews | 4507 (10.1) | 214.6 (90.8) | 6.86 | 3.99 | .63 | <.002 | 10.20 | .96 | <.002 |
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Clinical trials | 2718 (6.1) | 129.4 (59.8) | 9.23 | 7.05 | .73 | <.02 | 13.02 | .96 | <.002 |
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Historical articles | 2352 (5.3) | 112.0 (37.3) | 8.97 | 11.83 | .59 | <.02 | 8.03 | .54 | <.05 |
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Letters | 1234 (2.8) | 58.8 (11.9) | 1.91 | 12.59 | .54 | <.1 | 9.71 | .46 | <.1 |
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Editorials | 452 (1.0) | 21.5 (16.1) | 15.08 | -2.00 | .58 | <.02 | 37.32 | .71 | <.05 |
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Practice guidelines | 26 (<0.1) | 1.2 (1.2) | -4.55 | -25.0 | .03 | >.2 | 31.25 | .04 | >.2 |
aMann Kendall test for the trend
Number of high quality publications by year of publication.
The aim of this study was to characterize the overall and publication type-specific trends of scientific publications in military medicine over the last two decades. Over the study period, the number of publications related to the field of military medicine increased steadily. The rate of increase over time was not constant, as can clearly be seen from the figures. The slope indicating the mean annual incremental change increased substantially after 2001. This period coincides with the start of the global war on terror, and we speculate that the increased number of publications subsequent to that point in time is a derivative of this development. Alternatively, it is possible that this change is due to the temporal trends across disciplines and different publication types within PubMed. The observed pattern over time held true for most article types. The proportion of high quality research publications (RCT, systematic review, and meta-analysis) increased significantly over time. We interpret this as an indication of the increasing overall quality of the research conducted in the field of military medicine. Meta-analyses were hardly known in the 1990s [
The results of the regression analysis for the high quality publication types showed an increase in
Our study has several limitations. It is possible that our keyword search terms underestimated the overall number of military medical publications. Furthermore, the publication typing and tagging that is offered by PubMed may not be entirely accurate, with potential overlap between publication types. A misclassification error in publication type is also possible, for example, systematic reviews may not always be accurately identified as such by PubMed, since search filters do not always differentiate between the systematic reviews and meta-analyses and guidelines. (There is one such filter that is available at PubMed under "Clinical Queries", see the PubMed website). However, a random sample of retrieved articles examined manually showed an excellent degree of agreement with PubMed tags, and any overlap was observed mainly within the high quality publication types, specifically between RCTs and clinical trials, and between reviews, systematic reviews, and meta-analyses.
Our search strategy included publications whose authors carried a military affiliation. This strategy has yet to be validated, and it is possible that our data included articles published by military scholars, even if the subject matter was not directly associated with military medicine. Alternatively, our strategy may have included publications by scholars affiliated with military hospitals, but whose research was not necessarily military in nature. If this were true, it would be expected to increase the false-positive rate of our sample. Future research in this topic should consider alternative search strategies in order to enable a comparison between different methods.
In conclusion, over the past twenty years the field of military medicine has witnessed a significant increase in the publication of scholarly articles under various publication types, especially those considered to be of high quality. However, practice guidelines remain rare, and meta-analyses are still limited in number. We speculate that the increasing accessibility and availability of electronic resources to readers and authors will generate additional changes in publication trends in this field in the future.
medical subject headings
random controlled trials
None declared.