Publication characteristics of studies published in The Spine Journal from 2005 to 2015

There is a growing demand for evidence- based practices and informed clinical decision making supported by reliable, high-quality research. The aim of the study is to analyze trends in the level of evidence of publications and to evaluate the publication characteristics that influence the quality of research in The Spine Journal (TSJ). This is a comprehensive publication assessment that reviews and analyses all studies published in TSJ from the years 2005, 2007, 2009, 2011, 2013, and 2015. Level of evidence, study type, funding source, author country, author department, number of citations were considered as the outcome measures. Multivariable logistic regression, multivariable linear regression analyses, and chi square tests were used to analyze the trends of published studies level of evidence, study type, the specialties of authors, author countries, number of citations, and funding sources. A total of 1456 articles were evaluated. There was a decrease in the percentage of high-level evidence (level 1 and 2) studies from 73.6% in 2005 to 49.8% in 2015 (P=0.0045). There was a significant increase in the percentage studies with reporting funding support (P<0.0001). Funded studies were more likely to have a higher level of evidence (P<0.0001). The percentage of studies from international authors increased from 17.8% in 2005 to 69.1% in 2015 (P<0.0001). The percentage of studies with orthopedic authors decreased from 67% in 2005 to 44.9% in 2015 with a corresponding increase in the percentage of studies with neurosurgeon authors from 14.4% in 2005 to 23.2% by 2015, as well as an increase in the percentage of studies with a collaboration of authors from both specialties from 5.1% in 2005 to 8.7% in 2015 (P=0.0007). Orthopedic and neurosurgery collaboration in authorship did not affect the level of evidence of the studies nor the number of citations of the studies (P=0.7583). Earlier studies had a higher Scopus citation number but were not affected by the level of evidence (P=0.2515) nor the department of the author(s) (P=0.9107). We can conclude that the publication characteristics of articles in TSJ have evolved between 2005 and 2015 with a 3.9-fold increase in international authorship and a 32% decrease in the proportion of Level I and Level II studies. Inter-departmental collaboration, funding source, and country of origin may affect level of evidence and number of citations. Continued efforts to increase level of evidence should be considered.