Mammography screening increases non-breast cancer mortality (Peter Gøtzsche, 05 December 2013)
Erpeldinger et al. used the randomised trials to find out whether mammography screening increases non-breast cancer mortality. As we have explained in our Cochrane review (1), to which the authors refer, this cannot be done. One of the problems is that assignment of cause of death was biased in these trials, but the most important problem we describe in our review is this... read full comment
Comment on: Erpeldinger et al. Trials, 14:368
Response to comment by Hamilton et al. (Andreas Lundh, 22 November 2012)
`Owing to technical issues with the Trials comments page, the authors were unable to post this comment when originally submitted on the 5th... read full comment
Comment on: Lundh et al. Trials, 13:146
Addressing the implication made by the authors that if medical writers "do not do a job that satisfies the sponsors' marketing department, they might go out of business." (Cindy Hamilton, 20 September 2012)
To the... read full comment
Comment on: Lundh et al. Trials, 13:146
Efficacy due to alcohol or something else in the mouthwash composition? (Dirk Lachenmeier, 27 March 2012)
As it was previously noted, a considerable industry bias in mouthwash-related research exists . Therefore, it would be interesting to know the sponsor of the study and if the sponsor was affiliated with any of the mouthwash brands under... read full comment
Comment on: Marchetti et al. Trials, 12:262
Comparing apples and oranges (Joselita Salita, 21 July 2011)
I appreciate the goals of Nairy et al.'s paper. However, their primary objective was incomplete which made them design an experiment which compared apples and oranges. The three groups could only be partially compared: group 1 vs 2 and 1 vs 3, which in the end, could not support their conclusions.
In order to assess the efficacy of in-situ gels in treating OPC, one compares in-situ gels with a placebo or a comparator (in this case, flucanozole tablets) or both among one patient type. Having two types of patients, with one type incompletely represented was a major flaw. The choice of comparing responses among HIV/AIDS patients as a patient type was also not a good idea due to confounding effects. The resulting „good clinical response“ of HIV patients after 21... read full comment
Comment on: Nairy et al. Trials, 12:99
To the Editor (Dirk Kuhlmann, 23 June 2011)
The study showing an in situ gel formulation is an interesting approach for treatment of OPC. The clinical study data presented by Nairy et al. is poorly organized and confusing.
The reliability of the results is questionable due to incomplete outcome data and selection bias from randomization based on clinical evaluation. The three study groups are only partially comparable. As group II is missing a control group, the data is not supportive of the aim of the study.
Severity of signs and symptoms are mild to absent according to table 3. An effect of treatment on moderate to severe cases is not presented. Patient demographics of group 3 are diverse with a possible confounding bias associated with a large variance in CD4 count.
The primary endpoints are not... read full comment
Comment on: Nairy et al. Trials, 12:99
Systematizing the analysis of effect heterogeneity requires rethinking some fundamentals (James Scanlan, 01 June 2011)
The article by Gabler et al. questions the soundness of epidemiological literature’s reporting and analysis of heterogeneity of treatment effects (HTE) and calls for greater attention to HTE issues and more systematic analysis of such issues.
But the goals the authors seek cannot be achieved without reconsideration of certain fundamentals of subgroup analysis. Standard approaches to such analyses are based on an assumption that absent HTE all subgroups will experience equal proportionate changes in outcome rates (i.e., the same rate ratio across different baseline rates) and that HTE is observed in those cases where equal proportionate changes are not found. That assumption, however, is demonstrably unsound for the simple reason that it is not possible for a factor... read full comment
Comment on: Gabler et al. Trials, 10:43
Assessing heterogeneity of treatment effects in light fundamental statistical tendencies (James Scanlan, 26 May 2011)
The article by Kent et al. provides useful guidance on the reporting of results by subgroup. But the article suffers from the common assumption that the absence of a subgroup effect (heterogeneity) is reflected by equivalent relative risk reductions across subgroups. It is not logical to regard equivalent relative risk reductions as somehow normal (i.e., as reflecting the absence of a subgroup effect) for the simple reason that it is not possible for a factor to cause equal relative reductions in an outcome for groups with different base rates while causing equal relative increases in the opposite outcome for those groups.
The point can be illustrated with figures in Table 1 of Kent et al., which shows the same 25% relative risk reduction of an adverse outcome for an... read full comment
Comment on: Kent et al. Trials, 11:85
Erratum: minor error (Andrew Vickers, 30 November 2010)
In the text of our protocol, we gave an incorrect affiliation to JianPing Liu. He is not, as we suggested, affiliated with the Chinese Cochrane Center, but is Director of the Centre for Evidence-Based Chinese Medicine, Beijing University of Chinese Medicine. The last sentence of the "Search strategy for identification of studies" section should therefore read:
Chinese trials will be identified by a separate process: Jianping Liu of the Centre for Evidence-Based Chinese Medicine, Beijing University of Chinese Medicine, will use that institution's resources to identify Chinese trials of acupuncture for chronic pain that involved full allocation concealment.
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Comment on: Vickers et al. Trials, 11:90
Educational opportunities available to Trial and Data Managers (Rachel Breen, 01 September 2010)
I read with interest the article (provisional pdf) regarding Trial Management.
Managing clinical trials
Trials 2010, 11:78 doi:10.1186/1745-6215-11-78
Barbara Farrell, Sara Kenyon, Haleema Shakur.
However I felt that the article did not provide a balanced review of the educational opportunities available to Trials Managers and Data Managers. The article only mentioned the London School of Hygiene and Tropical Medicine's MSc in Clinical Trials. There are other MSc courses that have been developed to address trial management needs and could be argued to be more specific to the needs of Trial Managers than LSHTM. Examples include the Cranfield MSc and also MSc Clinical Research Administration run by the University of Liverpool, which is conducted completely in an... read full comment
Comment on: Farrell et al. Trials, 11:78
Searching for new insights in subgroup analyses (Ewout Steyerberg, 24 November 2009)
The SATIRE group is to be applauded for their effort to shed more light at the minefield of subgroup analysis, reporting, and interpretation. The question may however be what truly new insights will be obtained. One might predict that findings from a well-selected set of papers published in 2007 will be largely similar to what was found before in the studies shown in Table 1.
Of particular interest may be the answer to question 10 in Appendix 1: "Is the interaction consistent across closed related outcomes within the study?". In a previous individual patient data (IPD) meta-analysis of over 30,000 patients from 6 trials, we found statistically significant subgroup effects in 2 trials .. but in opposite directions . Identifying such IPD meta-analyses may be difficult when... read full comment
Comment on: Sun et al. Trials, 10:101
Protocol amendment to be implemented shortly (Peter Sandercock, 16 October 2009)
This comment is for information only
Protocol amendments. A number of minor changes to the IST-3 protocol document have been submitted for ethical and regulatory approval. The amended main trial protocol (and a supplementary protocol to describe the planned analyses of the cerebral perfusion data) will be posted on the IST3 website (www.ist3.com) when all the appropriate approvals have been obtained, in the near future.
Trial progress: By 16th October 2009, 1862 patients had been recruited, and the trial is on track to meet the target of 3100 patients by mid 2011.
For up to date information on recruitment and the implementation of the amendments please see www.ist3.com.
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Comment on: Sandercock et al. Trials, 9:37
The Pan African Clinical Trials Register (PACTR_: Compliance with the WHO minimum data-set in the first Pan African WHO-endorsed Primary Registry (Amber Abrams, 01 October 2009)
In the article “Compliance of clinical trial registries with the World Health Organization minimum data set : a survey” Moja et. al. explains that in September 2004, the International Committee of Medical Journal Editors (ICMJE) proposed “comprehensive trials registration as a solution to the problem of selective awareness and announce[d] that all 11 ICMJE member journals will adopt a trials-registration policy to promote this goal” (http://www.icmje.org/clin_trial.pdf). Thus, clinical trials must be publicly registered before the first participants are enrolled if the intention of the investigators is to publish findings in a medical journal.
To this end and to increase transparency and provide local registration opportunities for researchers who... read full comment
Comment on: Moja et al. Trials, 10:56
Re: Community-based trail of screening for Chlamydia trachomatis to prevent pelvic inflammatory disease: the POPI (prevention of pelvic infection) trial (T Aldeen, 19 December 2008)
I read your study with great interest as we still lack information about the natural history of Chlamydia and PID.
However, your diagnosis of PID relies mainly on the clinical history and I would like to remind you that PID may be symptomatic or asymptomatic and wonder how could you identify asymptomatic PID in your participants. Even symptomatic PID, clinical symptoms and signs lack sensitivity and specificity (the positive predictive value of a clinical diagnosis is 65-90% compared to laparoscopic diagnosis). Also the absence of genital Chlamydia infection does not exclude PID (http://www.bashh.org/documents/118/118.pdf).
Further, although the study information sheet explains the risk, it is challenging to leave women in the control arm with possible... read full comment
Comment on: Oakeshott et al. Trials, 9:73
Atherosclerotic (John Tanner, 23 February 2003)
Hello Dr. Ridker, I just came across your article re the anti-inflammatory effect of statin drugs in the cardiovasular system.Recently, I have had time to do extensive recent basic science literature review along with considerable antecdotal evidence beginning in the late 1970's along with current clinical research such as yours.It appears quite probable that overexpression of Cox 2 with its stimulation of the production of prostaglandin E2/kinins is the mediator of the inflammation known to exist in the coronary arteries of patients with atherosclerotic disease, for example. You and others have reasonably shown that the statin drugs benefit patients independently of their cholesterol lowering effects by acting in an anti-inflammatory manner.I would hypothesize that the action of the... read full comment
Comment on: Blake et al. Trials, 1:161