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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.


Papers
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Journal ArticleDOI
19 Jun 2013-JAMA
TL;DR: Compared with usual care, offers of health checks were not associated with lower rates of all-cause mortality, mortality from cardiovascular disease, or mortality from cancer, but health checks may be associated with more diagnoses and more drug treatment.
Abstract: Clinical Question What are the benefits and harms of general health checks for adult populations? Bottom Line Compared with usual care, offers of health checks were not associated with lower rates of all-cause mortality, mortality from cardiovascular disease, or mortality from cancer. Health checks may be associated with more diagnoses and more drug treatment. Morbidity was infrequently reported, as were most harms, such as use of diagnostic procedures.

37 citations

Journal ArticleDOI
TL;DR: No association was found between the CYP2D6 oxidation polymorphism and lung cancer risk when sample size bias was taken into account.
Abstract: To examine the association between the sparteine/debrisoquine (CYP2D6) oxidation polymorphism and the risk of lung cancer. Meta-analysis of case-control studies using a random effects model. The “Main outcome measure” was the odds ratio for the risk of lung cancer, using extensive metabolisers as the reference group. Thirteen studies were identified. The studies were too heterogeneous to be pooled the size of the odds ratio increased with the sample size. When the analysis was restricted to the largest studies, there was no difference in risk between poor and extensive metabolisers (odds ratio 0.95, 95% confidence interval 0.68–1.33). No association was found between the CYP2D6 oxidation polymorphism and lung cancer risk when sample size bias was taken into account.

37 citations

Journal ArticleDOI
23 Apr 2013-BMJ
TL;DR: Most authors of Cochrane reviews who searched for unpublished data received useful information, primarily from trialists andinvestigators, and manufacturers and regulatory agencies were uncommon sources of unpublished data.
Abstract: Objective To describe the experiences of authors of Cochrane reviews in searching for, getting access to, and using unpublished data. Design Cross sectional study. Setting Cochrane reviews. Participants 2184 corresponding authors of Cochrane reviews as of May 2012. Main outcome measure Frequencies of responses to open ended and closed questions in an online survey. Results Of 5915 authors contacted by email, 2184 replied (36.9% response rate). Of those, 1656 (75.8%) had searched for unpublished data. In 913 cases (55.1% of 1656), new data were obtained and we received details about these data for 794 data sources. The most common data source was “trialists/investigators,” accounting for 73.9% (n=587) of the 794 data sources. Most of the data were used in the review (82.0%, 651/794) and in 53.4% (424/794) of cases data were provided in less than a month. Summary data were most common, provided by 50.8% (403/794) of the data sources, whereas 20.5% (163/794) provided individual patient data. In only 6.3% (50/794) of cases were data reported to have been obtained from the manufacturers, and this group waited longer and had to make more contacts to get the data. The data from manufacturers were less likely to be for individual patients and less likely to be used in the review. Data from regulatory agencies accounted for 3.0% (24/794) of the obtained data. Conclusions Most authors of Cochrane reviews who searched for unpublished data received useful information, primarily from trialists. Our response rate was low and the authors who did not respond were probably less likely to have searched for unpublished data. Manufacturers and regulatory agencies were uncommon sources of unpublished data.

37 citations

Journal ArticleDOI
TL;DR: One often finds only what one looks for, e.g adverse events may be overlooked for a decade, if relatively uncommon, and retro‐ and prospective studies may give very different results.
Abstract: Mefloquine is widely used for the treatment of patients with chloroquine-resistant Plasmodium falciparum malaria. A 1987 report of possible mefloquine-induced toxic encephalopathy prompted an investigation by the manufacturer and the World Health Organization (WHO) of adverse psychiatric events associated with use of this antimalarial. Interim guidelines were issued by WHO in 1989 and a more systematic surveillance was initiated. Subsequent studies identified neuropsychiatric side effects in 1/159-1/1217 treated individuals. The authors of this paper launched a 3-year prospective study (1990-93) of 54 malaria patients treated with mefloquine at a medical center in Copenhagen Denmark and compared its results with those of their earlier (1982-88) retrospective study of 81 malaria patients treated at the same facility. No cases of adverse neurologic or neuropsychiatric sequelae were recorded in the retrospective study which did not specifically probe about such effects. In the prospective study which did include questions on this outcome 15 patients (28%) had one or more mild or moderate neuropsychiatric complaint (e.g. hallucinations nightmares depression anxiety sleeplessness and mania). Non-neuropsychiatric adverse reactions occurred in 78 patients (96%) in the retrospective study and 44 (81%) in the prospective study. These findings point out that studies conducted under virtually the same conditions may produce discrepant results depending on what is probed.

35 citations

Journal ArticleDOI
TL;DR: The present study supports the use of the impact factor as a rough quality indicator, however, even trials in high impact journals may be small or may have inadequate quality.

34 citations


Cited by
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Journal ArticleDOI
TL;DR: Moher et al. as mentioned in this paper introduce PRISMA, an update of the QUOROM guidelines for reporting systematic reviews and meta-analyses, which is used in this paper.
Abstract: David Moher and colleagues introduce PRISMA, an update of the QUOROM guidelines for reporting systematic reviews and meta-analyses

62,157 citations

Journal Article
TL;DR: The QUOROM Statement (QUality Of Reporting Of Meta-analyses) as mentioned in this paper was developed to address the suboptimal reporting of systematic reviews and meta-analysis of randomized controlled trials.
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

46,935 citations

Journal ArticleDOI
13 Sep 1997-BMJ
TL;DR: Funnel plots, plots of the trials' 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.
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

37,989 citations

Journal ArticleDOI
TL;DR: In this review the usual methods applied in systematic reviews and meta-analyses are outlined, and the most common procedures for combining studies with binary outcomes are described, illustrating how they can be done using Stata commands.

31,656 citations

Journal ArticleDOI
TL;DR: A structured summary is provided including, as applicable, background, objectives, data sources, study eligibility criteria, participants, interventions, study appraisal and synthesis methods, results, limitations, conclusions and implications of key findings.

31,379 citations