Descriptive analysis of cochrane child-relevant systematic reviews: an update and comparison between 2009 and 2013

Background: Systematic reviews support health systems and clinical decision-making by identifying and summarizing all existing studies on a particular topic. In 2009, a comprehensive description of child-relevant systematic reviews published in the Cochrane Database of Systematic Reviews was compiled. This study aims to provide an update, and to describe these systematic reviews according to their content and methodological approaches. Methods: All child-relevant systematic reviews published by the Cochrane Collaboration in the Cochrane Database of Systematic Reviews (CDSR) as of March, 2013 were identified and described in relation to their content and methodological approaches. This step equated to an update of the Child Health Field Review Register (CHFRR). The content of the updated CHFRR was compared to the published 2009 CHFRR description regarding clinical and methodological characteristics, using bivariate analyses. As the Cochrane Collaboration has recognized that disease burden should guide research prioritization, we extracted data from the Global and National Burden of Diseases and Injuries Among Children and Adolescents Between 1990 and 2013 study in order to map the distribution of the burden of disease in child health to the distribution of evidence across Review Groups in the CHFRR. Results: Of the 5,520 potential Cochrane systematic reviews identified, 1,293 (23.4%) were child-relevant (an increase of 24% since 2009). Overall, these reviews included 16,738 primary studies. The most commonly represented Review Groups were Airways (11.5%), Cystic Fibrosis and Genetic Diseases (7.9%), Acute Respiratory Infections (7.8%), Developmental, Psychological and Learning Problems (6.7%), and Infectious Diseases (6.2%). Corresponding authors were most often from Europe (51%), North America (15%), and Australia (15%). The majority of systematic reviews examined pharmacological interventions alone (52% compared to 59% in 2009). Out of 611 reviews that were assessed as up-to-date, GRADE was used in 204 (35%) reviews to assess the overall quality of the evidence, which was often moderate (35.6%) or low (37.8%) for primary outcomes. Ninety percent of reviews that were assessed as up to date used the Cochrane Risk of Bias tool, or a modified version, to assess methodological quality. Most reviews conducted one or more meta-analyses (73%). Among the 25 leading causes of death globally, the Review Groups associated with the largest number of causes were: 1) Infectious Diseases, 2) Anaesthesia, Critical, and Emergency Care, 3) Injuries, 4) Pregnancy and Childbirth (PC), and 5) Neonatal. There were large discrepancies between the number of causes of mortality that each Review Group was associated with and the total amount of evidence each Review Group contributed to the CHFRR. Ninety-eight percent of the causes of mortality in 2013 were from developing nations, but only 224 (17.3%) reviews had corresponding authors from developing countries. Conclusion: The content and methodological characteristics of child-relevant systematic reviews in the Cochrane CHFRR have been described in detail. There were modest advances in methods between 2009 and 2013. Systematic reviews contained in the CDSR offer an important resource for researcher's, clinicians and policy makers by synthesizing an extensive body of primary research. Further content analysis will allow the identification of clinical topics of greatest priority for future systematic reviews in child health.