Showing papers by "Peter C Gøtzsche published in 2008"

The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: Guidelines for reporting of observational studies

Abstract: Ein Grosteil der biomedizinischen Forschung ist beobachtend, und die Qualitat der veroffentlichten Berichte uber diese Forschung ist oft unzureichend. Dies behindert die Beurteilung der Starken und Schwachen einer Studie und ihrer Ubertragbarkeit. Die Strengthening the Reporting of Observational Studies in Epidemiology (STROBE-) Initiative hat Empfehlungen entwickelt, was in einem akkuraten und vollstandigen Bericht einer Beobachtungsstudie enthalten sein sollte. Die Empfehlungen wurden von uns so definiert, dass sie 3 Hauptstudientypen abdecken: Kohorten-, Fallkontroll- und Querschnittsstudien. Im September 2004 veranstalteten wir einen zweitagigen Workshop mit Methodikern, Forschern und Herausgebern wissenschaftlicher Zeitschriften, um eine Checkliste zu entwerfen. Anschliesend wurde der Entwurf bei mehreren Treffen der Koordinierungsgruppe und nach E-Mail-Diskussionen mit der erweiterten STROBE-Gruppe revidiert und dabei empirische Evidenz und methodologische Aspekte berucksichtigt. Das Ergebnis des Workshops und des anschliesenden iterativen Prozesses aus Beratung und Revision war eine Checkliste von 22 Punkten (STROBE-Statement), die sich auf die Bereiche Titel, Abstract, Einleitung, Methoden, Ergebnisse und Diskussion eines Artikels beziehen. 18 der Punkte sind relevant fur alle 3 Studiendesigns, wahrend 4 der Punkte spezifisch fur Kohorten-, Fallkontroll- und Querschnittsstudien sind. Ein ausfuhrlicher Begleitartikel („Explanation and Elaboration“) wurde separat veroffentlicht und ist auf den Webseiten von „PLoS Medicine“, „Annals of Internal Medicine“ und „Epidemiology“ frei zuganglich. Wir hoffen, dass das STROBE-Statement dazu beitragen kann, dass Beobachtungsstudien besser berichtet werden.

Recommendations by Cochrane Review Groups for assessment of the risk of bias in studies

Abstract: Assessing the risk of bias in individual studies in a systematic review can be done using individual components or by summarizing the study quality in an overall score. We examined the instructions to authors of the 50 Cochrane Review Groups that focus on clinical interventions for recommendations on methodological quality assessment of studies. Forty-one of the review groups (82%) recommended quality assessment using components and nine using a scale. All groups recommending components recommended to assess concealment of allocation, compared to only two of the groups recommending scales (P < 0.0001). Thirty-five groups (70%) recommended assessment of sequence generation and 21 groups (42%) recommended assessment of intention-to-treat analysis. Only 28 groups (56%) had specific recommendations for using the quality assessment of studies analytically in reviews, with sensitivity analysis, quality as an inclusion threshold and subgroup analysis being the most commonly recommended methods. The scales recommended had problems in the individual items and some of the groups recommending components recommended items not related to bias in their quality assessment. We found that recommendations by some groups were not based on empirical evidence and many groups had no recommendations on how to use the quality assessment in reviews. We suggest that all Cochrane Review Groups refer to the Cochrane Handbook for Systematic Reviews of Interventions, which is evidence-based, in their instructions to authors and that their own guidelines are kept to a minimum and describe only how methodological topics that are specific to their fields should be handled.

House dust mite control measures for asthma.

Abstract: Background The major allergen in house dust comes from mites. Chemical, physical and combined methods of reducing mite allergen levels are intended to reduce asthma symptoms in people who are sensitive to house dust mites. Objectives The objective of this review is to assess the effects of reducing exposure to house dust mite antigens in the homes of mite-sensitive asthmatics, assessing chemical and physical methods separately and together. Search strategy We searched the Cochrane Airways Group trials register, checked reference lists of articles and hand-searched Respiration (1980 to 1996) and Clinical and Experimental Allergy (1980 to 1996). The Cochrane Library is searched every three months. Selection criteria Randomised trials of mite control measures vs placebo or no treatment in asthmatic people known to be sensitive to house dust mites. Data collection and analysis Two reviewers applied the trial inclusion criteria, assessed their quality and extracted the data independently. Study authors were contacted to clarify information. Main results Twenty-nine trials (939 patients in the analyses) were included, with two trials awaiting assessment. Nine trials assessed chemical methods alone, 15 physical methods alone, and 5 a combination of chemical and physical methods. Overall, there was no statistically significant difference improvement of asthma (relative risk 1.04, 95% confidence interval 0.83 to 1.31), asthma symptom scores (standardised mean difference -0.07, 95% confidence interval -0.35 to 0.22), medication usage (standardised mean difference -0.14, 95% confidence interval -0.43 to 0.15), or peak flow in the morning (standardised mean difference 0.04, 95% confidence interval -0.13 to 0.21). For chemical methods used alone, there was a statistically significantly adverse effect on symptoms (P = 0.03), whereas for physical methods used alone as evaluated in parallel group trials, there was a statistically significant beneficial effect (P = 0.02). However, because of the large number of significance tests we performed, two significant results would be expected to occur by chance. Reviewers' conclusions Currently available evidence from controlled trials of chemical and physical approaches to reducing exposure to house dust mite antigens in the homes of mite-sensitive asthmatics does not provide a secure basis for advice and policy. Further trials one of them very large - are currently in progress. The additional evidence from these studies will help to clarify whether or not the substantial efforts required to implement strategies intended to reduce mites can be expected to yield beneficial effects of a magnitude that people with mite sensitive asthma consider worthwhile.

Discrepancies in sample size calculations and data analyses reported in randomised trials: comparison of publications with protocols.

Abstract: Objective To evaluate how often sample size calculations and methods of statistical analysis are pre-specified or changed in randomised trials. Design Retrospective cohort study. Data source Protocols and journal publications of published randomised parallel group trials initially approved in 1994-5 by the scientific-ethics committees for Copenhagen and Frederiksberg, Denmark (n=70). Main outcome measure Proportion of protocols and publications that did not provide key information about sample size calculations and statistical methods; proportion of trials with discrepancies between information presented in the protocol and the publication. Results Only 11/62 trials described existing sample size calculations fully and consistently in both the protocol and the publication. The method of handling protocol deviations was described in 37 protocols and 43 publications. The method of handling missing data was described in 16 protocols and 49 publications. 39/49 protocols and 42/43 publications reported the statistical test used to analyse primary outcome measures. Unacknowledged discrepancies between protocols and publications were found for sample size calculations (18/34 trials), methods of handling protocol deviations (19/43) and missing data (39/49), primary outcome analyses (25/42), subgroup analyses (25/25), and adjusted analyses (23/28). Interim analyses were described in 13 protocols but mentioned in only five corresponding publications. Conclusion When reported in publications, sample size calculations and statistical methods were often explicitly discrepant with the protocol or not pre-specified. Such amendments were rarely acknowledged in the trial publication. The reliability of trial reports cannot be assessed without having access to the full protocols.

[The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies].

Abstract: A pesar de que la mayor parte de la investigacion biomedica es de tipo observacional, la informacion difundida sobre estas investigaciones es a menudo insuficiente, lo que dificulta la evaluacion de sus puntos fuertes y debiles para la generalizacion de sus conclusiones. En el marco de la iniciativa STROBE (Strengthening the Reporting of Observational Studies in Epidemiology), se formularon las recomendaciones sobre lo que deberia contener una notificacion precisa de un estudio observacional. Decidimos limitar el alcance de las recomendaciones a tres grandes modalidades de estudio: de cohortes, de casos y controles, y transversales. En septiembre de 2004 organizamos un taller de 2 dias con metodologos, investigadores y editores de revistas para elaborar una lista de verificacion de distintos puntos. Esta lista fue revisada posteriormente en varias reuniones del grupo de coordinacion y en discusiones mantenidas por correo electronico con los principales participantes en STROBE, teniendo en cuenta la evidencia empirica y diversas consideraciones metodologicas. El taller y el posterior proceso iterativo de consulta y revision desembocaron en una lista de verificacion de 22 puntos (la declaracion STROBE) que guardan relacion con el titulo, el resumen, la introduccion y las secciones de metodos, resultados y discusion de los articulos. Dieciocho puntos son comunes a los tres tipos de estudio, y cuatro son especificas para cada uno de ellos. Se ha publicado separadamente un documento de explicacion y elaboracion al que puede accederse libremente en los sitios web de PLoS Medicine, Annals of Internal Medicine y Epidemiology. Esperamos que la declaracion STROBE contribuya a mejorar la calidad de la publicacion de los estudios observacionales.

[The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting of observational studies].

Abstract: Ein Grosteil der biomedizinischen Forschung ist beobachtend, und die Qualitat der veroffentlichten Berichte uber diese Forschung ist oft unzureichend. Dies behindert die Beurteilung der Starken und Schwachen einer Studie und ihrer Ubertragbarkeit. Die Strengthening the Reporting of Observational Studies in Epidemiology (STROBE-) Initiative hat Empfehlungen entwickelt, was in einem akkuraten und vollstandigen Bericht einer Beobachtungsstudie enthalten sein sollte. Die Empfehlungen wurden von uns so definiert, dass sie 3 Hauptstudientypen abdecken: Kohorten-, Fallkontroll- und Querschnittsstudien. Im September 2004 veranstalteten wir einen zweitagigen Workshop mit Methodikern, Forschern und Herausgebern wissenschaftlicher Zeitschriften, um eine Checkliste zu entwerfen. Anschliesend wurde der Entwurf bei mehreren Treffen der Koordinierungsgruppe und nach E-Mail-Diskussionen mit der erweiterten STROBE-Gruppe revidiert und dabei empirische Evidenz und methodologische Aspekte berucksichtigt. Das Ergebnis des Workshops und des anschliesenden iterativen Prozesses aus Beratung und Revision war eine Checkliste von 22 Punkten (STROBE-Statement), die sich auf die Bereiche Titel, Abstract, Einleitung, Methoden, Ergebnisse und Diskussion eines Artikels beziehen. 18 der Punkte sind relevant fur alle 3 Studiendesigns, wahrend 4 der Punkte spezifisch fur Kohorten-, Fallkontroll- und Querschnittsstudien sind. Ein ausfuhrlicher Begleitartikel (Explanation and Elaboration) wurde separat veroffentlicht und ist auf den Webseiten von PLoS Medicine, Annals of Internal Medicine und Epidemiology frei zuganglich. Wir hoffen, dass das STROBE-Statement dazu beitragen kann, dass Beobachtungsstudien besser berichtet werden.

Somatostatin analogues for acute bleeding oesophageal varices.

Abstract: BACKGROUND Somatostatin and its derivatives are often used for emergency treatment of bleeding oesophageal varices in patients with cirrhosis of the liver. The placebo controlled trials have shown varying results, however, and their power has been quite low. An updated systematic review of a previously published meta-analysis was therefore performed. OBJECTIVES To study whether somatostatin or analogues improve survival or reduce the number of blood transfusions in patients with suspected or verified acute or recently bleeding oesophageal varices. SEARCH STRATEGY MEDLINE and The Cochrane Library were searched in August 2001. Reference lists of articles and authors. SELECTION CRITERIA All randomised trials comparing somatostatin or analogues with placebo or no treatment in patients suspected of acute bleeding from oesophageal varices. DATA COLLECTION AND ANALYSIS The effect variables extracted were: mortality, number of blood transfusions, number with balloon tamponade, number with initial haemostasis and number with rebleeding. Intention to treat analyses were conducted; a random effects analysis was preferred if there was significant heterogeneity between the trials (P < 0.10). MAIN RESULTS The meta-analysis comprised 12 trials and 1452 patients. The active drugs did not reduce mortality significantly (relative risk 0.93, 95% confidence interval (CI) 0.75 to 1.14). The number of transfusions was less with drugs, the difference between experimental and control therapy was 1.0 units of blood products (95% CI 0.6 to 1.5). Number of patients failing initial haemostasis was also reduced (relative risk 0.68, 95% CI 0.50 to 0.92). There were no significant differences in use of balloon tamponade (relative risk 0.68, 95% CI 0.37 to 1.24), or in number of patients with rebleeding (relative risk 0.61, 95% CI 0.35 to 1.09). It should be noted, however, that the trials were heterogeneous with respect to the secondary outcomes. REVIEWER'S CONCLUSIONS The effect corresponded to one unit of blood saved per patient. It can be discussed whether this effect is worthwhile. The findings do not suggest a need for further placebo-controlled studies of somatostatin analogues in acute bleeding from oesophageal varices. On the other hand, the confidence interval for the effect on mortality was wide. Hence, a large placebo controlled trial is needed if one wishes to rule out the possibility that a worthwhile effect on mortality may have been overlooked.

Industry-supported meta-analyses compared with meta-analyses with non-profit or no support: Differences in methodological quality and conclusions

Abstract: Background Studies have shown that industry-sponsored meta-analyses of drugs lack scientific rigour and have biased conclusions. However, these studies have been restricted to certain medical specialities. We compared all industry-supported meta-analyses of drug-drug comparisons with those without industry support.

STROBE Statement: linee guida per descrivere gli studi osservazionali

Abstract: Much of 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 generalizability. 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, casecontrol, 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. Eighteen 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 web sites 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.

Topical NSAIDs have unknown effectiveness

Abstract: Dieppe claimed in an editorial about osteoarthritis that topical non-steroidal anti-inflammatory drugs (NSAIDs) are as effective as oral NSAIDs.1 He refers to a report from the National Institute for Health and Clinical Excellence (NICE), which describes two meta-analyses. He notes that the authors assessed the trials for quality, but the 424 page report says nothing about that quality. The …