Peter C Gøtzsche

Bio: Peter C Gøtzsche is an academic researcher from Cochrane Collaboration. The author has contributed to research in topics: Systematic review & Placebo. The author has an hindex of 90, co-authored 413 publications receiving 147009 citations. Previous affiliations of Peter C Gøtzsche include University of Copenhagen & Copenhagen University Hospital.

Results of the Two-County trial of mammography screening are not compatible with contemporaneous official Swedish breast cancer statistics.

Abstract: BACKGROUND National mammography screening programmes are based on the results of randomised trials, but the quality of these trials has recently been questioned. The Swedish Two-County trial reported a 31% reduction in breast cancer mortality and was instrumental for the introduction of screening in many countries. In this trial, official Swedish health registries were used to identify breast cancers and breast cancer deaths in the study population. METHODS We used data from the same registries to estimate the numbers of breast cancer cases and breast cancer deaths among the included women. RESULTS Compared to official Swedish statistics we found that 192 breast cancer cases and 43 breast cancer deaths seem to be missing in the main publication of the Two-County trial; we found similar discrepancies in two updates of the trial. These large differences can hardly be explained by random fluctuations in the cancer occurrence. CONCLUSION The data reported for the Two-County trial are incomplete. Other data indicate that the mortality results in a recent report were flawed.

Intravenous alpha-1 antitrypsin augmentation therapy: systematic review.

Abstract: We reviewed the benefits and harms of augmentation therapy with alpha-1 antitrypsin in patients with alpha-1 antitrypsin deficiency and lung disease. We searched for randomised trials comparing augmentation therapy with placebo or no treatment in PubMed and ClinicalTrials (7 January 2010). Two trials were included with a total of 140 patients. The trials ran for two to three years. Mortality data were not reported. There was no information on harms in the first trial; in the second trial, serious adverse events were reported in ten of 38 patients in the drug group and in 18 of 39 patients in the placebo group. Annual number of exacerbations and quality of life were reported in the second trial and were similar in the two groups. The meta-analyses showed that forced expiratory volume in one second deteriorated a little more in the drug group than in the placebo group (difference -20 ml per year; 95% confidence interval -41 to 1; p = 0.06). For carbon monoxide diffusion, the difference was -0.06 mmol/min./kPa per year (95% confidence interval -0.17 to 0.05; p = 0.31). Lung density measured by computed tomography deteriorated a little less in the drug group than in the placebo group (difference 1.14 g/l; 95% confidence interval 0.14 to 2.14; p = 0.03) over the total course of the trials. Augmentation therapy with alpha-1 antitrypsin cannot be recommended in view of the lack of evidence of clinical benefit and the cost of treatment.

Coding of adverse events of suicidality in clinical study reports of duloxetine for the treatment of major depressive disorder: descriptive study

Abstract: Objective To assess the effects of coding and coding conventions on summaries and tabulations of adverse events data on suicidality within clinical study reports.

Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement

Abstract: David Moher and colleagues introduce PRISMA, an update of the QUOROM guidelines for reporting systematic reviews and meta-analyses

Preferred reporting items for systematic reviews and meta-analyses: the PRISMA Statement.

Abstract: Systematic reviews and meta-analyses have become increasingly important in health care. Clinicians read them to keep up to date with their field,1,2 and they are often used as a starting point for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure there is justification for further research,3 and some health care journals are moving in this direction.4 As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' ability to assess the strengths and weaknesses of those reviews. Several early studies evaluated the quality of review reports. In 1987, Mulrow examined 50 review articles published in 4 leading medical journals in 1985 and 1986 and found that none met all 8 explicit scientific criteria, such as a quality assessment of included studies.5 In 1987, Sacks and colleagues6 evaluated the adequacy of reporting of 83 meta-analyses on 23 characteristics in 6 domains. Reporting was generally poor; between 1 and 14 characteristics were adequately reported (mean = 7.7; standard deviation = 2.7). A 1996 update of this study found little improvement.7 In 1996, to address the suboptimal reporting of meta-analyses, an international group developed a guidance called the QUOROM Statement (QUality Of Reporting Of Meta-analyses), which focused on the reporting of meta-analyses of randomized controlled trials.8 In this article, we summarize a revision of these guidelines, renamed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses), which have been updated to address several conceptual and practical advances in the science of systematic reviews (Box 1). Box 1 Conceptual issues in the evolution from QUOROM to PRISMA

Bias in meta-analysis detected by a simple, graphical test

Abstract: Objective: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses. Design: Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30% of the trial); analysis of funnel plots from 37 meta-analyses identified from a hand search of four leading general medicine journals 1993-6 and 38 meta-analyses from the second 1996 issue of the Cochrane Database of Systematic Reviews . Main outcome measure: Degree of funnel plot asymmetry as measured by the intercept from regression of standard normal deviates against precision. Results: In the eight pairs of meta-analysis and large trial that were identified (five from cardiovascular medicine, one from diabetic medicine, one from geriatric medicine, one from perinatal medicine) there were four concordant and four discordant pairs. In all cases discordance was due to meta-analyses showing larger effects. Funnel plot asymmetry was present in three out of four discordant pairs but in none of concordant pairs. In 14 (38%) journal meta-analyses and 5 (13%) Cochrane reviews, funnel plot asymmetry indicated that there was bias. Conclusions: A simple analysis of funnel plots provides a useful test for the likely presence of bias in meta-analyses, but as the capacity to detect bias will be limited when meta-analyses are based on a limited number of small trials the results from such analyses should be treated with considerable caution. Key messages Systematic reviews of randomised trials are the best strategy for appraising evidence; however, the findings of some meta-analyses were later contradicted by large trials Funnel plots, plots of the trials9 effect estimates against sample size, are skewed and asymmetrical in the presence of publication bias and other biases Funnel plot asymmetry, measured by regression analysis, predicts discordance of results when meta-analyses are compared with single large trials Funnel plot asymmetry was found in 38% of meta-analyses published in leading general medicine journals and in 13% of reviews from the Cochrane Database of Systematic Reviews Critical examination of systematic reviews for publication and related biases should be considered a routine procedure