title: Hierarchy of evidence referring to the central nervous system in a high-impact radiation oncology journal: a 10-year assessment. Descriptive critical appraisal study.
abstract: OBJECTIVE
  To the best of our knowledge, there has been no systematic assessment of the classification of scientific production within the scope of radiation oncology relating to central nervous system tumors. The aim of this study was to systematically assess the status of evidence relating to the central nervous system and to evaluate the geographic origins and major content of these published data.
  
  
  METHODS
  Descriptive critical appraisal study conducted at a private hospital in São Paulo, Brazil.
  
  
  METHODS
  We evaluated all of the central nervous system studies published in the journal Radiotherapy & Oncology between 2003 and 2012. The studies identified were classified according to their methodological design and level of evidence. Information regarding the geographical location of the study, the institutions and authors involved in the publication, main condition or disease investigated and time of publication was also obtained.
  
  
  RESULTS
  We identified 3,004 studies published over the 10-year period. Of these, 125 (4.2%) were considered eligible, and 66% of them were case series. Systematic reviews and randomized clinical trials accounted for approximately 10% of all the published papers. We observed an increase in high-quality evidence and a decrease in low-quality published papers over this period (P = 0.036). The inter-rater reliability demonstrated significant agreement between observers in terms of the level of evidence.
  
  
  CONCLUSIONS
  Increases in high-level evidence and in the total number of central nervous system papers were clearly demonstrated, although the overall number of such studies remained relatively small.
authors.affiliation: Department of Radiation Oncology, Hospital Sírio-Libanês, São Paulo, Brazil.
authors.forename: Fabio Ynoe
authors.initials: FY
authors.lastname: Moraes
authors.affiliation: Department of Radiation Oncology, Hospital Sírio-Libanês, São Paulo, Brazil.
authors.forename: Lorine Arias
authors.initials: LA
authors.lastname: Bonifacio
authors.affiliation: Department of Radiation Oncology, Hospital Sírio-Libanês, São Paulo, Brazil.
authors.forename: Gustavo Nader
authors.initials: GN
authors.lastname: Marta
authors.affiliation: Department of Radiation Oncology, Hospital Sírio-Libanês, São Paulo, Brazil.
authors.forename: Samir Abdallah
authors.initials: SA
authors.lastname: Hanna
authors.affiliation: Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Álvaro Nagib
authors.initials: ÁN
authors.lastname: Atallah
authors.affiliation: Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Vinícius Ynoe
authors.initials: VY
authors.lastname: Moraes
authors.affiliation: Department of Radiation Oncology, Hospital Sírio-Libanês, São Paulo, Brazil.
authors.forename: João Luis Fernandes
authors.initials: JL
authors.lastname: Silva
authors.affiliation: Department of Radiation Oncology, Hospital Sírio-Libanês, São Paulo, Brazil.
authors.forename: Heloísa Andrade
authors.initials: HA
authors.lastname: Carvalho
mesh_terms: D001319:Authorship; D015706:Bibliometrics; D016543:Central Nervous System Neoplasms / Q000532:radiotherapy*; D019317:Evidence-Based Medicine / Q000706:statistics & numerical data*; D006801:Humans; D010506:Periodicals as Topic / Q000706:statistics & numerical data*; D036301:Qualitative Research; D015203:Reproducibility of Results; D012107:Research Design / Q000706:statistics & numerical data