Design and level of evidence of studies published in two Brazilian medical journals recently indexed in the ISI Web of Science database

Abstract

CONTEXT AND OBJECTIVES:The level of evidence and methodological quality of articles published in medical journals are important aids for clinicians in decision-making and also affect journals' impact factor. Although systematic reviews (SR) are considered to represent the highest level of evidence, their methodological quality is not homogeneous and they need to be as carefully assessed as other types of study. This study aimed to assess the design and level of evidence of articles published in 2007, in two recently indexed Brazilian journals (Clinics and Revista da Associação Médica Brasileira), and to evaluate the methodological quality of the SRs. DESIGN AND SETTING:Descriptive study developed in the Brazilian Cochrane Center, Universidade Federal de São Paulo.METHODS: All 289 published articles were classified according to types of study design and level of evidence. The SRs were critically appraised by two evaluators using the AMSTAR tool. RESULTS:The most frequent design types were cross-sectional studies (39.9%), case reports (15.8%), experimental studies (10.8%) and narrative reviews (7.4%). According to the Oxford criteria, 25.6% of the articles were classified as level 4 or 5 evidence, while 2.8% were level 1. SRs represented only 2% of the published articles and their methodological quality scores were low. CONCLUSIONS:The main design types among the published papers were observational and experimental studies and narrative reviews. SRs accounted for a small proportion of the articles and had low methodological scores. Brazilian medical journals need to encourage publication of greater numbers of clinically relevant papers of high methodological quality.RESUMO CONTEXTO E OBJETIVOS: O nível de evidência e a qualidade metodológica dos artigos publicados em revistas médicas são importantes para auxiliar os clínicos a tomarem decisões e também afetam o fator de impacto dos periódicos. Apesar de as revisões sistemáticas (RS) serem consideradas o maior nível de evidência, sua qualidade metodológica não é homogênea e elas precisam ser avaliadas tão criteriosamente como outros tipos de estudos. O objetivo deste estudo foi avaliar os desenhos e nível de evidência dos artigos publicados em 2007 em duas revistas brasileiras recentemente indexadas (Clinics e Revista da Associação Médica Brasileira) e avaliar a qualidade metodológica das RS. TIPO DE ESTUDO E LOCAL:Estudo descritivo desenvolvido no Centro Cochrane do Brasil, Universidade Federal de São Paulo. MÉTODOS:Todos os 289 artigos publicados foram classificados quanto ao tipo de desenho e nível de evidência. As RS foram analisadas criticamente por dois revisores usando o instrumento AMSTAR.RESULTADOS: Os tipos de desenhos mais frequentes foram os transversais (39,9%), relatos de casos (15,8%), estudos experimentais (10,8%) e revisões narrativas (7,4%). Segundo os critérios de Oxford, 25,6% dos artigos eram de nível 4 ou 5 e 2,8% de nível 1. As RS representaram apenas 2% do total dos artigos publicados e tiveram notas de qualidade metodológica baixas...

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