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Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): Explanation and Elaboration

Vandenbroucke, Jan P.*; von Elm, Erik†‡; Altman, Douglas G.§; Gøtzsche, Peter C.; Mulrow, Cynthia D.; Pocock, Stuart J.**; Poole, Charles††; Schlesselman, James J.‡‡; Egger, Matthias†§§for the STROBE Initiative

doi: 10.1097/EDE.0b013e3181577511
STROBE Initiative

Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalizability of its results. Taking into account empirical evidence and theoretical considerations, a group of methodologists, researchers, and editors developed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations to improve the quality of reporting of observational studies.

The STROBE Statement consists of a checklist of 22 items, which relate to the title, abstract, introduction, methods, results and discussion sections of articles. Eighteen items are common to cohort studies, case-control studies and cross-sectional studies and four are specific to each of the three study designs. The STROBE Statement provides guidance to authors about how to improve the reporting of observational studies and facilitates critical appraisal and interpretation of studies by reviewers, journal editors and readers.

This explanatory and elaboration document is intended to enhance the use, understanding, and dissemination of the STROBE Statement. The meaning and rationale for each checklist item are presented. For each item, one or several published examples and, where possible, references to relevant empirical studies and methodological literature are provided. Examples of useful flow diagrams are also included. The STROBE Statement, this document, and the associated web site ( should be helpful resources to improve reporting of observational research.

From the *Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands; †Institute of Social & Preventive Medicine (ISPM), University of Bern, Bern, Switzerland; ‡Department of Medical Biometry and Medical Informatics, University Medical Centre, Freiburg, Germany; §Cancer Research UK/NHS Centre for Statistics in Medicine, Oxford, UK; ¶Nordic Cochrane Centre, Rigshospitalet, Copenhagen, Denmark; ∥University of Texas Health Science Center, San Antonio, USA; **Medical Statistics Unit, London School of Hygiene and Tropical Medicine, London, UK; ††Department of Epidemiology, University of North Carolina School of Public Health, Chapel Hill, NC; ‡‡Department of Biostatistics, University of Pittsburgh Graduate School of Public Health, and University of Pittsburgh Cancer Institute, Pittsburgh, PA; §§Department of Social Medicine, University of Bristol, Bristol, UK.

The initial STROBE workshop was funded by the European Science Foundation (ESF). Additional funding was received from the Medical Research Council Health Services Research Collaboration and the National Health Services Research & Development Methodology Programme. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Editors’ note: In order to encourage dissemination of the STROBE Statement, this article is freely accessible on the Web site of Epidemiology ( and will also be published on the Web sites of Annals of Internal Medicine and PLoS Medicine. The authors jointly hold the copyright of this article. For details on further use, see the STROBE website ( ). Related articles appear on pages 789, 791, 792, 794, 797, and 800.

This paper is being published simultaneously in Annals of Internal Medicine, Epidemiology, and PLoS Medicine.

Correspondence: Matthias Egger, Institute of Social and Preventive Medicine (ISPM), Finkenhubelweg 11, CH-3012 Bern, Switzerland. E-mail:

© 2007 Lippincott Williams & Wilkins, Inc.