scispace - formally typeset
Search or ask a question

Showing papers by "Peter C Gøtzsche published in 2002"


Journal ArticleDOI
05 Jun 2002-JAMA
TL;DR: A substantial proportion of reviews had evidence of honorary and ghost authorship, and the Cochrane editorial teams contributed to most Cochrane reviews.
Abstract: ContextTo determine the prevalence of honorary and ghost authorship in Cochrane reviews, how authorship is assigned, and the ways in which authors and Cochrane editorial teams contribute.MethodsUsing a Web-based, self-administered survey, corresponding authors for 577 reviews published in issues 1 and 2 from 1999 of The Cochrane Library were invited to report on the prevalence of honorary and ghost authors, contributions by authors listed in the byline and members of Cochrane editorial teams, and identification of methods of assigning authorship. Responses were received for 362 reviews (63% response rate), which contained 913 authors.ResultsOne hundred forty-one reviews (39%) had evidence of honorary authors, 32 (9%) had evidence of ghost authors (most commonly a member of the Cochrane editorial team), and 9 (2%) had evidence of both honorary and ghost authors. The editorial teams contributed in a wide variety of ways to 301 reviews (83%). Authorship was decided by the group of authors (31%) or lead author (25%) in most reviews. Authorship order was assigned according to contribution in most reviews (76%). The 3 functions contributed to most by those listed in the byline were assessing the quality of included studies (83%), interpreting data (82%), and abstracting data from included studies (77%).ConclusionsA substantial proportion of reviews had evidence of honorary and ghost authorship. The Cochrane editorial teams contributed to most Cochrane reviews.

229 citations


Reference EntryDOI
TL;DR: There was no evidence that placebo interventions in general have clinically important effects, and a possible moderate effect on subjective continuous outcomes, especially pain, could not be clearly distinguished from bias.
Abstract: Background Placebo interventions are often believed to improve patient reported and observer reported outcomes, but this belief is not based on evidence from randomised trials that compare placebo with no treatment. Objectives To assess the effect of placebo interventions. Search strategy We searched the Cochrane Controlled Trials Register (The Cochrane Library, issue 3, 1998), MEDLINE (Jan 1966 to Dec 1998), EMBASE (Jan 1980 to Dec 1998), Biological Abstracts (Jan 1986 to Dec 1998), PsycLIT (Jan 1887 to Dec 1998). Experts on placebo research were contacted and references in the included trials were read. Selection criteria Randomised placebo trials with a no-treatment control group investigating any health problem were included. Data collection and analysis Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. Main results Outcome data were available in 114 out of 130 included trials, investigating 40 clinical conditions. Outcomes were binary in 32 trials (3795 patients) and continuous in 82 (4730 patients). We found no statistically significant pooled effect of placebo in studies with binary outcomes, relative risk 0.95 (95 per cent confidence interval 0.88 to 1.02). The pooled relative risk for subjective (patient reported) outcomes was 0.95 (0.86 to 1.05) and for objective (observer reported) outcomes 0.91 (0.80 to 1.04). There was statistically significant heterogeneity (P < 0.03), but no evidence of sample size bias (P = 0.56). We found an overall positive effect of placebo treatments in trials with continuous outcomes, standardised mean difference -0.28 (95 per cent confidence interval -0.38 to -0.19). The standardised mean difference for subjective outcomes was -0.36 (-0.47 to -0.25), whereas no statistically significant effect was found for objective outcomes, standardised mean difference -0.12 (-0.27 to 0.03). There was statistically significant heterogeneity (P < 0.001), and evidence of sample size bias (P = 0.05). There was no statistically significant effect of placebo interventions in eight out of nine clinical conditions investigated in three trials or more (nausea, relapse in prevention of smoking and depression, overweight, asthma, hypertension, insomnia and anxiety), but confidence intervals were wide. There was a modest apparent analgesic effect of placebo interventions, standardised mean difference -0.27 (-0.40 to -0.15), but also a substantial risk of bias. Reviewers' conclusions There was no evidence that placebo interventions in general have clinically important effects. A possible moderate effect on subjective continuous outcomes, especially pain, could not be clearly distinguished from bias.

46 citations


Journal ArticleDOI
TL;DR: A 3-year project to identify and make accessible reports of randomized trials published in European general health care journals ensures that a large proportion of trial reports not previously identifiable has been made accessible to those preparing systematic reviews.
Abstract: A fundamental aim of any systematic review is that all relevant studies should be identified and considered for inclusion. Limitations with searching bibliographic databases led the Cochrane Collaboration to search journals by hand for reports of trials. This article presents the results of a 3-year project to identify and make accessible reports of randomized trials published in European general health care journals. Overall, 21,620 reports of controlled trials were identified from119 journals from16 countries. More than three quarters (76%) were published in U.K. or German journals. Only 3,640 (17%) reports were indexed in MEDLINE as controlled trials, and 6,554 (30%) were not indexed in MEDLINE at all. Bibliographic details for all reports are available by searching The Cochrane Controlled Trials Register in The Cochrane Library. This project has ensured that a large proportion of trial reports not previously identifiable has been made accessible to those preparing systematic reviews.

22 citations


Journal Article
TL;DR: In the Netherlands, almost 10% of people in the Netherlands had used a non-aspirin NSAID in 1987; the overall use was 11 defined daily doses (see box) per 1000 persons a day; the defined daily dose per 1000 population per day is an estimate of the proportion of that population receiving treatment with that drug as discussed by the authors.
Abstract: Definition Non-steroidal anti-inflammatory drugs (NSAIDs) have anti-inflammatory, analgesic, and antipyretic effects and inhibit thrombocyte aggregation. The drugs have no documented effect on the disease process itself. Incidence/prevalence NSAIDs are widely used. Almost 10% of people in the Netherlands had used a non-aspirin NSAID in 1987; the overall use was 11 defined daily doses (see box) per 1000 persons a day.1 In Australia in 1994, overall use was 35 defined daily doses per 1000 persons a day, with 36% of the people receiving NSAIDs for osteoarthritis, 42% for sprain and strain or low back pain, and 4% for rheumatoid arthritis; 35% were aged over 60 years.2 Aims To reduce symptoms in rheumatic disorders; to avoid severe gastrointestinal adverse effects. Outcomes Primary outcomes: pain intensity, person's preference for one drug over another, global efficacy, and clinically significant gastrointestinal complications. Secondary outcomes: number of tender joints, perforation, gastrointestinal haemorrhage, dyspepsia, and ulcer detected by routine endoscopy. Defined daily dose : The assumed average daily dose for the main indication of a specified drug. The defined daily dose per 1000 population per day is an estimate of the proportion of that population receiving treatment with that drug. We searched Medline and the Cochrane Library in July 1999 for systematic reviews and randomised controlled trials (RCTs) that included at least 100 people. More than 100 meta-analyses and thousands of RCTs have compared various NSAIDs. Many trials are unpublished or published in sources that are not indexed in publicly available databases. The quality of the trials is variable and bias is common, both in the design and analysis of the trials, to such an extent that a systematic review identified false significant findings favouring new drugs over control drugs in 6% of trials.3 #### Interventions ##### Beneficial: NSAIDs in rheumatoid arthritis Misoprostol in high risk patients who …

20 citations





Journal Article
TL;DR: In the authors' opinion, based on evidence accrued over decades of scientific research on breast cancer screening, and countless, independent expert peer reviews of the study designs, data, and conclusions of the trials, the scientific foundation for the value of early breast cancer detection with mammography is sound.

4 citations


Journal ArticleDOI

3 citations







Journal Article
TL;DR: A systematic review of clinical trials in which patients were randomised either to placebo treatment or to no treatment found no reliable evidence that placebo treatments in general had effects of clinical importance.
Abstract: Introduction: Placebo treatments have been reported to help patients with many diseases, but the quality of the evidence supporting this belief has not been rigorously evaluated. Material and methods: We conducted a systematic review of clinical trials in which patients were randomised either to placebo treatment or to no treatment. A placebo intervention could be pharmacological (for instance, a tablet), physical (for instance manipulation), or psychological (for instance conversation). Results: We identified 130 trials that met our inclusion criteria. After excluding 16, which gave no relevant outcome data, 32 with binary outcomes and 82 with continuous outcomes were left. As compared to no treatment, placebo had no significant effect on binary outcomes, the pooled relative risk was 0.95 (95% confidence interval 0.88 to 1.02), irrespective of whether these outcomes were subjective or objective. Placebo seemed to have a beneficial effect in the trials with continuous outcomes, the overall pooled standardised mean difference of the placebo and no-treatment groups was -0.28 (-0.38 to -0.19), but the effect decreased with increasing sample size, which indicates bias. The pooled standardised mean difference was significant for the trials with subjective outcomes, -0.36 (-0.47 to -0.25), but not for those with objective outcomes, -0.12 (-0.27 to 0.03). In trials involving the treatment of pain, placebo was reported to have a moderate beneficial effect, with a pooled standardised mean difference of -0.27 (-0.40 to -0.15), but bias, for instance reporting bias, was possible. Conclusion: We found no reliable evidence that placebo treatments in general had effects of clinical importance.