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general surgery boasts remarkable developments and refinements in basic science , diagnosis and treatment that have transcended abdominal organs , touching neighboring and more distal branches of medicine .
advances in scientific surgical research have benefited the care of men and women of all ages .
because publications inspire future articles , a paper s scientific impact can be measured in terms of the number of citations received.1 increasing numbers of scientific papers in the internet era have provided diverse information .
the frequency of citations serves as a rough guide to the importance of an article . the impact factor ( if )
is now generally used to measure the prestige of journals , the influence of articles published in those journals and , by extension , the authors , institutions and countries.2 in brazil , the national agency ( cnpq ) dedicated to promoting scientific and technological research has used the if as an indicator of the national research output and to define investment priorities.3 in this paper , our goal was to identify the most frequently cited articles published by brazilian authors in the most - cited international journals dedicated to general surgery .
we aimed to provide an opportunity to recognize key historical advances and the evolution of surgery research in brazil .
to identify the most frequently cited brazilian papers published in general surgery journals , we accessed the thompson web of knowledge database ( institute for scientific information - isi).4 inclusion criteria included articles with at least one brazilian author and published in the 26 highly cited journals in the field of general surgery .
these journals were selected based on their 2008 impact factor ( journal citation report ) .
the articles were identified and analyzed with respect to their authors , institution , year of publication , number of citations and topics .
of the 208,168 articles included in the study , 1,713 ( 0.8% ) were published by brazilian authors .
nine were cited over 100 times , and these were considered classics.5 the 26 screened journals are listed in table 1 . analyzing the ranking of each country
brazilian contributions to those journals are listed by decades and presented in table 2 . regarding brazil s overall contribution , a rising curve was evident , with brazil climbing from the 34 position ( 0.07% ) in the seventies to the 13 position in the 2000s ( 1.47% ) .
figure 1 shows the number of brazilian papers published in each year since 1970 . because only nine brazilian articles reached the classic denomination ( article with more than 100 citations ) , we further evaluated all of the articles with more than 30 citations ( the top 65 articles ) .
table 3 summarizes the designs of the 65 articles identified to have more than 30 citations .
we observed a tendency for retrospective series and cohorts ( 56.9% ) , while randomized trials accounted for 10/65 ( 15.3% ) articles .
twelve ( 18.4% ) experimental studies were included in the list of the top 65 .
brazilian top 65  included oncology , transplantation , trauma and critical care , as listed in table 4 .
the topics most frequently covered by the top 65 articles were shock and kidney transplantation at 10 articles each ( 15.3% ) , followed by colorectal tumors in 9 ( 13.8% ) articles .
the second most heavily cited theme was trauma / critical care and organ transplantation , accounting for 15/65 ( 22.9% ) articles each . aside from these principal categories ,
bariatric surgery and gi endoscopy were covered in 4/65 ( 6.1% ) papers each ( table 4 ) .
the range of citations varied from 49 to 194 , with an average of 85 citations per article .
international collaboration was relevant since the earliest article to make the list , published in 1984 by abe s et al .
( gama - rodrigues ) , described early gastric cancer in japan.6 the most recent classic ( 102 citations ) , published by tedesco - silva et al . in 2005 , was a phase ii international clinical trial describing the immunologic response to fty720 in kidney transplantation.7 indeed , eighteen articles ( 60% ) on this list were written with international co - authorship .
the article ranked in first place on the list was published in the nineties by cutait et al . and discussed colorectal cancer staging based on immunohistochemical analysis of micrometastasis in lymph nodes.8 analyzing the individual contribution by state , institutions from sao paulo authored or co - authored 65% of these articles .
the most - published institutions were the university of sao paulo / hospital de clinicas ( usp ) , the federal university of sao paulo ( unifesp ) , campinas state university ( unicamp ) and albert einstein hospital , contributing 619 , 173 , 87 and 87 papers , respectively .
nevertheless , notable contributions came from others states , such as rio de janeiro , rio grande do sul , minas gerais and parana ( table 6 ) .
general surgery is a discipline encompassing clinical knowledge , operative techniques and scientific foundations , including wound healing , infection , metabolism , immunology , shock and resuscitation . in this paper , we recognized articles that were published in the most cited general surgery journals , had at least one author with a brazilian affiliation , were identified in the isi web of knowledge database and were published during a 39-year period ( 1970 to 2009 ) . in total ,
a limitation of our results is that we have no information on citations in journals not covered by the isi bibliometric database .
undoubtedly , the results of this citation analysis could be different if more latin american scientific journals were listed in the isi web of knowledge or if another citation database , such as scopus , had been selected .
another aspect that must be taken into consideration is that , until recently , only articles published in english were considered by the jcr .
the 26 screened journals were the periodicals dedicated to general surgery with the highest impact factor .
these international journals receive contributions from all over the world , publishing milestone publications in experimental and clinical surgery .
although english is not the native language in brazil , our country has an established place in the general surgery literature . nowadays ,
brazilian authors have the 19 overall position in terms of the number of papers published in these renowned journals .
the contribution of papers from brazilian authors in these journals is encouraging , as the proportion of the global total increased by about 21-fold , from 0.07% in the 1970s to 1.47% in the 2000s . nonetheless , brazil is behind small developing countries , such as taiwan , and it just recently surmounted turkey .
the overwhelming supremacy of united states was evident , as the united states was the top contributing country in 23 of 26 screened journals , publishing more than 52% of all papers . in the 2000s ,
brazil occupied the 13 overall position . in our point of view , this ascension can be partially attributed to the support of the brazilian national council , which is dedicated to promoting science in our country . in addition , more international exchange opportunities , widespread use of the internet and more surgeons dedicated to basic and clinical research could be responsible for the rising curve of publications over the years.9 however , the english language can be a barrier , and other types of biases ( bias towards nationality ) can influence the approval rate.2 we recognize that the scielo ( scientific electronic library online ) database increased the visibility of brazilian medical literature during the past decade .
the scielo will probably also contribute to increasing the impact of national journals devoted to surgery .
these data reflect , at least in part , the evolution of a specific surgical area .
for example , a better comprehension of the physiology of obesity , transplantation and laser therapy resulted in great amounts of new information and motivated the establishment of new journals .
concerning bariatric surgery , brazilian authors have published continually in journals like obesity surgery , where brazil holds the 3 overall position .
although surgeons are conscious of the importance of evidence - based medicine , only 10 ( 15.3% ) articles were randomized clinical trials .
prior studies corroborated these observations in other medical areas , including trauma , general surgery , urology and critical care medicine.5 , 1012 interestingly , international collaboration and multicenter trials seem to be needed for a paper to be highly cited because 7 of the 9 classics ( > 100 citations ) have authors from different countries . in the 1980s , 9/71 ( 12.6% ) articles had inter - institutional collaboration .
in the 1990s , 32/182 ( 17.1% ) articles published by brazilian authors had this characteristic , and after 2000 , 185 of 1441 ( 12.8% ) articles had international collaboration .
in the top 65 articles ( > 30 citations ) , the united states was the country whose investigators most frequently collaborated with brazilian authors ( 18/65 ; 27.7% ) .
general surgery is a heterogeneous medical specialty , covering different areas in men and women s health , basic science , clinical practice and operative techniques .
the list of the top - cited articles covers some of the hottest topics in surgery today , such as surgical oncology , minimally invasive approaches and organ transplantation . in the most cited article concerning trauma and critical care ,
from the university of california and in collaboration with younes from usp published a meta - analysis demonstrating similar efficacy between hypertonic and isotonic solutions in trauma .
previously , younes et al . reported a cohort of memorial sloan - kettering patients and analyzed perioperative risk factors and the recurrence of colorectal metastases ( 4 overall ) .
the same author published the best - ranked brazilian experimental study concerning the use of hypertonic saline in dogs ( positioned 16 ) .
( usp ) and covered the activity of thiopurine methyltransferase in immunosuppressive therapy in renal transplantation .
the oldest article in the list of the top 65 was published in 1979 by paulino et al .
the same group addressed the use of radiotherapy and chemotherapy in low rectal cancer ( 10 ) and more recently published two articles reporting the long - term results of operative treatment for rectal cancer following chemotherapy ( 14 and 60 ) .
although our search included the 26 most - cited general surgery journals , we are aware that restricting our search to these journals is a limitation of the present study .
some of the most cited brazilian papers were published in more specific or general journals ; these include the description of the  jatene procedure  for the correction of transposition of the great arteries , which was published in the journal of thoracic and cardiovascular surgery in 1976 ; the use of hypertonic nacl for the treatment of severe hemorrhagic shock , which was published in the american journal of physiology in 1980 ; and the first description of liver transplantation from a living donor , which was published by raia et al . in 1989 in the lancet .
these articles have been cited 243 , 258 and 262 times , respectively.1315 this analysis highlighted the academic influence and popularity of southeast institutions .
historically , sao paulo institutions provided financial and technological support for research . for decades ,
the university of sao paulo - hospital de clinicas has been the top published institution .
however , highly contributing institutions are now also based in other states , such as rio de janeiro , rio grande do sul , minas gerais and parana .
in recent years , citation analysis , although imperfect , has become common and is considered to be the currency of journal prestige .
the selected journals have always attracted the submission of advances and landmark articles in general surgery .
this study is an opportunity to remember the most - cited brazilian articles and to learn from distinguished brazilian surgeons , recognizing the remarkable impact that these visionaries have had in national surgery .
objectivesto identify the most cited articles in general surgery published by brazilian authors.introductionthere are several ways for the international community to recognize the quality of a scientific article . although controversial , the most widely used and reliable methodology to identify the importance of an article is citation analysis.methodsa search using the institute for scientific information citation database ( science citation index expanded ) was performed to identify highly cited brazilian papers published in twenty - six highly cited general surgery journals , selected based on their elevated impact factors , from 1970 to 2009 . 
 further analysis was done on the 65 most - cited papers.resultswe identified 1,713 brazilian articles , from which nine papers emerged as classics ( more than 100 citations received ) . for the brazilian contributions , 
 a total increase of about 21-fold was evident between 1970 and 2009 . 
 although several topics were covered , articles covering trauma , oncology and organ transplantation were the most cited . 
 the majority of classic studies were done with international cooperation.conclusionsthis study identified the most influential brazilian articles published in internationally renowned general surgery journals .