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Much biomedical research is observational. The reporting of such research is often inadequate, which hampers the assessment of its strengths and weaknesses and of a study's 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 to improving the quality of reporting of observational studies.

Background: Not all clinical trials are published, which may distort the evidence that is available in the literature. We studied the publication rate of a cohort of clinical trials and identified factors associated with publication and nonpublication of results., Methods: We analysed the protocols of randomized clinical trials of drug interventions submitted to the research ethics committee of University Hospital (Inselspital) Bern, Switzerland from 1988 to 1998. We identified full articles published up to 2006 by searching the Cochrane CENTRAL database (issue 02/2006) and by contacting investigators. We analyzed factors associated with the publication of trials using descriptive statistics and logistic regression models., Results: 451 study protocols and 375 corresponding articles were analyzed. 233 protocols resulted in at least one publication, a publication rate of 52%. A total of 366 (81%) trials were commercially funded, 47 (10%) had non-commercial funding. 346 trials (77%) were multi-centre studies and 272 of these (79%) were international collaborations. In the adjusted logistic regression model non-commercial funding (Odds Ratio [OR] 2.42, 95% CI 1.14-5.17), multi-centre status (OR 2.09, 95% CI 1.03-4.24), international collaboration (OR 1.87, 95% CI 0.99-3.55) and a sample size above the median of 236 participants (OR 2.04, 95% CI 1.23-3.39) were associated with full publication., Conclusions: In this cohort of applications to an ethics committee in Switzerland, only about half of clinical drug trials were published. Large multi-centre trials with non-commercial funding were more likely to be published than other trials, but most trials were funded by industry.

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 (http://www.strobe-statement.org) should be helpful resources to improve reporting of observational research.

Background: Abstracts of presentations at scientific meetings are usually available only in conference proceedings. If subsequent full publication of abstract results is based on the magnitude or direction of study results, publication bias may result. Publication bias, in turn, creates problems for those conducting systematic reviews or relying on the published literature for evidence., Objectives: To determine the rate at which abstract results are subsequently published in full, and the time between meeting presentation and full publication. To assess the association between study characteristics and full publication., Search Strategy: We searched MEDLINE, EMBASE, The Cochrane Library, Science Citation Index, reference lists, and author files. Date of most recent search: June 2003., Selection Criteria: We included all reports that examined the subsequent full publication rate of biomedical results initially presented as abstracts or in summary form. Follow-up of abstracts had to be at least two years., Data Collection and Analysis: Two reviewers extracted data. We calculated the weighted mean full publication rate and time to full publication. Dichotomous variables were analyzed using relative risk and random effects models. We assessed time to publication using Kaplan-Meier survival analyses., Main Results: Combining data from 79 reports (29,729 abstracts) resulted in a weighted mean full publication rate of 44.5% (95% confidence interval (CI) 43.9 to 45.1). Survival analyses resulted in an estimated publication rate at 9 years of 52.6% for all studies, 63.1% for randomized or controlled clinical trials, and 49.3% for other types of study designs.'Positive' results defined as any 'significant' result showed an association with full publication (RR = 1.30; CI 1.14 to 1.47), as did 'positive' results defined as a result favoring the experimental treatment (RR =1.17; CI 1.02 to 1.35), and 'positive' results emanating from randomized or controlled clinical trials (RR = 1.18, CI 1.07 to 1.30). Other factors associated with full publication include oral presentation (RR = 1.28; CI 1.09 to 1.49); acceptance for meeting presentation (RR = 1.78; CI 1.50 to 2.12); randomized trial study design (RR = 1.24; CI 1.14 to 1.36); and basic research (RR = 0.79; CI 0.70 to 0.89). Higher quality of abstracts describing randomized or controlled clinical trials was also associated with full publication (RR = 1.30, CI 1.00 to 1.71)., Authors' Conclusions: Only 63% of results from abstracts describing randomized or controlled clinical trials are published in full. 'Positive' results were more frequently published than not 'positive' results.

Objective: To review the efficacy of pharmacological prevention of serious reactions to iodinated contrast media., Design: Systematic review., Data Sources: Systematic search (multiple databases, bibliographies, all languages, to October 2005) for randomised comparisons of pretreatment with placebo or no treatment (control) in patients receiving iodinated contrast media. Review methods Trial quality was assessed by all investigators. Information on trial design, population, interventions, and outcomes was abstracted by one investigator and cross checked by the others. Data were combined by using Peto odds ratios with 95% confidence intervals., Results: Nine trials (1975-96, 10 011 adults) tested H1 antihistamines, corticosteroids, and an H1-H2 combination. No trial included exclusively patients with a history of allergic reactions. Many outcomes were not allergy related, and only a few were potentially life threatening. No reports on death, cardiopulmonary resuscitation, irreversible neurological deficit, or prolonged hospital stays were found. In two trials, 3/778 (0.4%) patients who received oral methylprednisolone 2x32 mg or intravenous prednisolone 250 mg had laryngeal oedema compared with 11/769 (1.4%) controls (odds ratio 0.31, 95% confidence interval 0.11 to 0.88). In two trials, 7/3093 (0.2%) patients who received oral methylprednisolone 2x32 mg had a composite outcome (including shock, bronchospasm, and laryngospasm) compared with 20/2178 (0.9%) controls (odds ratio 0.28, 0.13 to 0.60). In one trial, 1/196 (0.5%) patients who received intravenous clemastine 0.03 mg/kg and cimetidine 2-5 mg/kg had angio-oedema compared with 8/194 (4.1%) controls (odds ratio 0.20, 0.05 to 0.76)., Conclusions: Life threatening anaphylactic reactions due to iodinated contrast media are rare. In unselected patients, the usefulness of premedication is doubtful, as a large number of patients need to receive premedication to prevent one potentially serious reaction. Data supporting the use of premedication in patients with a history of allergic reactions are lacking. Physicians who are dealing with these patients should not rely on the efficacy of premedication.

Cerebral blood flow is thought to increase at high altitude and in subjects suffering from acute mountain sickness (AMS); however, data from the literature are contentious. Blood flow velocity in the middle cerebral artery (MCAv) may be used as a proxy measure of cerebral blood flow. Using transcranial Doppler sonography, MCAv was measured during normo- and hyper-ventilation in subjects who participated in a trial that tested the effect of magnesium supplementation on the prevention of AMS. First, MCAv was recorded at 353 m (baseline). Subjects were then randomized to receive oral magnesium citrate and matching placebo. A second measurement was taken after a 24 +/- 2 h ascent from 1130 m to 4559 m (altitude I), and a third after a 20-24 h stay at 4559 m (altitude II). Using multivariate linear regression, an association was sought between MCAv and magnesium supplementation, subjects' age and gender, altitude itself, a temporary stay at altitude, and the presence of AMS (Lake Louise Score >6 with ataxia, nausea and/or headache). Subjects with AMS had additional Doppler recordings immediately before and after rescue medication (oxygen, dexamethasone and acetazolamide). Forty-seven subjects had measurements at baseline, 39 (21 receiving magnesium and 18 placebo) at altitude I and 26 (13 receiving magnesium and 13 placebo) at altitude II. During hyperventilation, MCAv decreased consistently (for each measurement, P<0.001). Magnesium significantly increased MCAv by 8.4 cm.s(-1) (95% confidence interval, 1.8-15), but did not prevent AMS. No other factors were associated with MCAv. Eleven subjects had severe AMS [median score (range), 11 (8-16)] and, after rescue medication, the median score decreased to 3 (range, 0-5; P=0.001), but MCAv remained unchanged (65 +/- 18 cm.s(-1) before compared with 67 +/- 16 cm.s(-1) after rescue medication; P=0.79). MCAv was increased in subjects who received magnesium, but was not affected by exposure to high altitude or by severe AMS.

Context: Duplicate publication is publication of an article that overlaps substantially with an article published elsewhere. Patterns of duplication are not well understood., Objective: To investigate duplication patterns and propose a decision tree for classification., Data Sources: We searched a comprehensive list of systematic reviews (1989 through August 15, 2002) in anesthesia and analgesia that is accessible on the Internet. We selected published full articles of duplicates that had been identified in these systematic reviews. Abstracts, letters, or book chapters were excluded., Study Selection and Data Extraction: Authors of 56 (40%) of 141 systematic reviews acknowledged identification of duplicates. Duplication patterns were identified independently by all investigators comparing samples and outcomes of pairs of duplicates and main articles. Information on cross-reference, sponsorship, authorship, and publication characteristics was extracted from the articles., Data Synthesis: The 56 systematic reviews included 1131 main articles (129 337 subjects) and excluded 103 duplicates (12 589 subjects) that originated from 78 main articles. Sixty articles were published twice, 13 three times, 3 four times, and 2 five times. We identified 6 duplication patterns: (1A) identical samples and identical outcomes (21 pairs); (1B) same as 1A but several duplicates assembled (n = 16); (2) identical samples and different outcomes (n = 24); (3A) increasing sample and identical outcomes (n = 11); (3B) decreasing sample and identical outcomes (n = 11); (4) different samples and different outcomes (n = 20). The prevalence of covert duplicate articles (without a cross-reference to the main article) was 5.3% (65/1234). Of the duplicates, 34 (33%) were sponsored by the pharmaceutical industry, and 66 (64%) had authorship that differed partly or completely from the main article. The median journal impact factor was 1.8 (range, 0.1-29.5) for duplicates and 2.0 (range, 0.4-29.5) for main articles (P =.13). The median annual citation rate was 1.7 (range, 0-27) for duplicates and 2.1 (range, 0-31) for main articles (P =.45). The median number of authors was 4 (range, 1-14) for duplicates and 4 (range, 1-15) for corresponding main articles (P =.02). The median delay in publication between main articles and duplicates was 1 year (range, 0-7 years)., Conclusions: Duplication goes beyond simple copying. Six distinct duplication patterns were identified after comparing study samples and outcomes of duplicates and corresponding main articles. Authorship was an unreliable criterion. Duplicates were published in journals with similar impact factors and were cited as frequently as main articles.

Background: It has been estimated that about 45% of abstracts that are accepted for presentation at biomedical meetings will subsequently be published in full. The acceptance of abstracts at meetings and their fate after initial rejection are less well understood. We set out to estimate the proportion of abstracts submitted to meetings that are eventually published as full reports, and to explore factors that are associated with meeting acceptance and successful publication., Methods: Studies analysing acceptance of abstracts at biomedical meetings or their subsequent full publication were searched in MEDLINE, OLDMEDLINE, EMBASE, Cochrane Library, CINAHL, BIOSIS, Science Citation Index Expanded, and by hand searching of bibliographies and proceedings. We estimated rates of abstract acceptance and of subsequent full publication, and identified abstract and meeting characteristics associated with acceptance and publication, using logistic regression analysis, survival-type analysis, and meta-analysis., Results: Analysed meetings were held between 1957 and 1999. Of 14945 abstracts that were submitted to 43 meetings, 46% were accepted. The rate of full publication was studied with 19123 abstracts that were presented at 234 meetings. Using survival-type analysis, we estimated that 27% were published after two, 41% after four, and 44% after six years. Of 2412 abstracts that were rejected at 24 meetings, 27% were published despite rejection. Factors associated with both abstract acceptance and subsequent publication were basic science and positive study outcome. Large meetings and those held outside the US were more likely to accept abstracts. Abstracts were more likely to be published subsequently if presented either orally, at small meetings, or at a US meeting. Abstract acceptance itself was strongly associated with full publication., Conclusions: About one third of abstracts submitted to biomedical meetings were published as full reports. Acceptance at meetings and publication were associated with specific characteristics of abstracts and meetings.