8 In this paper we describe the updating of that guidance. 7 That rationale led to the development of the QUOROM (quality of reporting of meta-analysis) statement those detailed reporting recommendations were published in 1999. 3 4 5 6 As is true for all research, systematic reviews should be reported fully and transparently to allow readers to assess the strengths and weaknesses of the investigation. Unfortunately, there is considerable evidence that key information is often poorly reported in systematic reviews, thus diminishing their potential usefulness.

2 Recent data suggest that at least 2500 new systematic reviews reported in English are indexed in Medline annually. They help clinicians keep up to date provide evidence for policy makers to judge risks, benefits, and harms of healthcare behaviours and interventions gather together and summarise related research for patients and their carers provide a starting point for clinical practice guideline developers provide summaries of previous research for funders wishing to support new research 1 and help editors judge the merits of publishing reports of new studies. Systematic reviews and meta-analyses are essential tools for summarising evidence accurately and reliably. The PRISMA statement, this document, and the associated website ( should be helpful resources to improve reporting of systematic reviews and meta-analyses. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. In this explanation and elaboration document, we explain the meaning and rationale for each checklist item. The checklist includes items deemed essential for transparent reporting of a systematic review. The PRISMA statement consists of a 27-item checklist and a four-phase flow diagram. Realising these issues, an international group that included experienced authors and methodologists developed PRISMA (preferred reporting items for systematic reviews and meta-analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Since the development of the QUOROM (quality of reporting of meta-analysis) statement-a reporting guideline published in 1999-there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users. The clarity and transparency of these reports, however, are not optimal. Systematic reviews and meta-analyses are essential to summarise evidence relating to efficacy and safety of healthcare interventions accurately and reliably. 13Department of Epidemiology and Community Medicine, Faculty of Medicine, Ottawa, Ontario, Canada.12School for Public Health and Primary Care (CAPHRI), University of Maastricht, Maastricht, Netherlands.10Departments of Medicine, Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada.9School of Nursing and Midwifery, Trinity College, Dublin, Republic of Ireland.7Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece.6Nordic Cochrane Centre, Copenhagen, Denmark.5Annals of Internal Medicine, Philadelphia, Pennsylvania, USA.4Ottawa Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.3Centre for Statistics in Medicine, University of Oxford, Oxford.2Centro Cochrane Italiano, Istituto Ricerche Farmacologiche Mario Negri, Milan, Italy.1UniversitГ di Modena e Reggio Emilia, Modena, Italy.

Origin 8 cutler 7