STROBE StatementThe Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studiesErik von Elm, Douglas G Altman, Matthias Egger, Stuart J Pocock, Peter C Gotzsche, Jan P Vandenbroucke, for the STROBE initiativeMuch biomedical research is observational. The reporting of such research is often inadequate, which hampers the assessment of its strengths and weaknesses and of a studys generalisability. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) initiative developed recommendations on what should be included in an accurate and complete report of an observational study. We defined the scope of the recommendations to cover three main study designs: cohort, case-control, and cross-sectional studies. We convened a 2-day workshop in September, 2004, with methodologists, researchers, and journal editors to draft a checklist of items. This list was subsequently revised during several meetings of the coordinating group and in e-mail discussions with the larger group of STROBE contributors, taking into account empirical evidence and methodological considerations. The workshop and the subsequent iterative process of consultation and revision resulted in a checklist of 22 items (the STROBE statement) that relate to the title, abstract, introduction, methods, results, and discussion sections of articles. 18 items are common to all three study designs and four are specific for cohort, case-control, or cross-sectional studies. A detailed explanation and elaboration document is published separately and is freely available on the websites of PLoS Medicine, Annals of Internal Medicine, and Epidemiology. We hope that the STROBE statement will contribute toLancet 2007; 370:1453-57Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland (E von Elm MD, Prof M Egger MD); Centre for Statistics in Medicine, University of Oxford, Oxford, UK (Prof DG Altman DSc); Department of Social Medicine, University of Bristol, Bristol, UK (M Egger); London School of Hygiene and Tropical Medicine, University of London, London, UK (Prof S J Pocock PhD); Nordic Cochrane Centre, Copenhagen, Denmark (P C Gotzsche MD); and Department of Clinical Epidemiology, Leiden University Hospital Leiden, Netherlands (Prof J PVandenbroucke MD)Correspondence to: Dr Erik von Elm, Institute of Social and Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland strobe@ispm.unibe.chimproving the quality of reporting of observational studies.IntroductionMany questions in medical research are investigated in observational studies.1 Much of the research into the cause of diseases relies on cohort, case-control, or cross-sectional studies. Observational studies also have a role in research into the benefits and harms of medical interventions? Randomised trials cannot answer all important questions about a given intervention. For example, observational studies are more suitable to detect rare or late adverse effects of treatments, and are more likely to provide an indication of what is achieved in daily medical practice.5Research should be reported transparently so that readers can follow what was planned, what was done, what was found, and what conclusions were drawn. The credibility of research depends on a critical assessment by others of the strengths and weaknesses in study design, conduct, and analysis. Transparent reporting is also needed to judge whether and how results can be included in systematic reviews.45 However, in published observational research important information is often missing or unclear. An analysis of epidemiological studies published in general medical and specialist journals found that the rationale behind the choice of potential confounding variables was often not reported.6 Only a few reports of case-control studies in psychiatry explained the methods used to identify cases and controls.7 In a survey of longitudinal studies in stroke research, 17 of 49 articles (35%) did not specify the eligibility criteria.8 Others have argued that without sufficient clarity of reporting, the benefits of research might be achieved more slowly,9 and that there is a need fbr guidance in reporting observational studies.1011Recommendations on the reporting of research can improve reporting quality. The Consolidated Standards of Reporting Trials (CONSORT) statement was devel oped in 1996 and revised 5 years later.12 Many medical journals supported this initiative,0 which has helped to improve the quality of reports of randomised trials.14,15 Similar initiatives have followed fbr other research areas—eg, fbr the reporting of meta-analyses of randomised trials16 or diagnostic studies?7 We estab lished a network of methodologists, researchers, and journal editors to develop recommendations fbr the reporting of observational research: the Strengthe。