A multistudy analysis investigating systematic differences in cardiovascular trial results between Europe and Asia.

Objective: To assess whether there are differences in the results of cardiovascular trials between Europe and Asia using data from an extensive collection of randomised controlled trials.

Study Design And Setting: All meta-analyses containing randomised controlled trials (RCT's) for the treatment or prevention of cardiovascular diseases were searched for in The Cochrane Library (2000-2008) and MEDLINE (2005-2008). Analysis was then conducted within and over each meta-analysis which satisfied given criteria.

Are cardiovascular trial results systematically different between North America and Europe? A study based on intra-meta-analysis comparisons.

Background: It is often assumed that differences in the efficacy of treatments between countries (or regions) will be neither negligible nor minor and therefore cannot be overlooked when assessing the potential benefit of treatments in one country (or region) on the basis of trials conducted in another country (or region).

Aim: To assess differences in the results of cardiovascular trials between Europe and North America on the basis of data from an extensive collection of trials.

Methods: A systematic search was conducted of Medline (from the year 2005 to 2008) and the Cochrane Library (from 2000 to 2008) for all meta-analyses of randomized controlled trials aimed at treating and preventing cardiovascular disease.

Efficacy of adjuvant chemotherapy after surgery when considered over all cancer types: a synthesis of meta-analyses.

Background: Despite a large number of clinical trials having been conducted to assess the efficacy of adjuvant chemotherapy after surgery for various cancers, whether it is best to use this treatment remains a generally contentious issue for many common cancers. The purpose of this study was to ascertain whether any general conclusions can be drawn about the efficacy or inefficacy of this treatment within different cancer classifications.

Methods: Meta-analyses of randomized, controlled trials (RCTs) of adjuvant chemotherapy after surgery were synthesized over as many types of cancer as possible.

Pooling systematic reviews of systematic reviews: a Bayesian panoramic meta-analysis.

Systematic reviews and meta-analyses usually synthesise evidence from studies reporting outcomes from particular interventions in specific diseases. For example, a meta-analysis of prophylactic antibiotics (intervention) in elective arterial reconstruction (disease) for rates of wound infection (outcome). However, because systematic reviews and meta-analyses are so widespread, a body of evidence often exists around specific intervention effects on particular outcomes over a range of diseases.

Estimating changes in overall survival using progression-free survival in metastatic breast and colorectal cancer.

Objectives: In clinical trials of new cancer drugs, reliable data for progression-free survival will often become available far sooner than reliable data for overall survival. The aim of this study was to determine how many months it would be expected that any given new drug for metastatic breast or colorectal cancer will add to overall survival times given that the number of months the drug adds to progression-free survival times relative to a standard drug is roughly already known.

Methods: A literature search was conducted over Medline for randomized controlled trials (RCTs) published between January 1980 and August 2008 that assessed the effect of a drug treatment in comparison to an alternative drug treatment on patients with either metastatic breast or metastatic colorectal cancer.

Clinical effectiveness in cardiovascular trials in relation to the importance to the patient of the end-points measured.

Background: In order to increase the statistical power of a trial design, it is common practice for trialists to place a strong emphasis on end-points other than mortality. To assess the validity of this practice, the aim of this study was to investigate the relationship between the effectiveness of cardiovascular interventions in clinical trials and the importance to the patient of the end-point used to measure this effectiveness.

Methods: A reanalysis of a database of cardiovascular trials used in an earlier study.

Is antibiotic prophylaxis in surgery a generally effective intervention? Testing a generic hypothesis over a set of meta-analyses.

Context: While the main focus of a meta-analysis is often to assess the effectiveness of a particular intervention in managing or curing a specific condition, there exists a substantial amount of information within published systematic reviews that could be used to assess the validity of a generic hypothesis about the effectiveness of an intervention across a range of different but related conditions.

Objective: To systematically search for and then collate the results of meta-analyses for the effectiveness of antibiotic prophylaxis in preventing postoperative wound infection across various types of surgery in order to assess generic hypotheses about the effectiveness of this intervention in surgery as a whole. With the relative risk of wound infection used as the measure of clinical effectiveness, the hypotheses to be assessed were first that antibiotic prophylaxis would be an effective intervention for preventing wound infection over a broad range of different surgical procedures, and second that there would be a substantial difference in the effectiveness of antibiotic prophylaxis between "clean" and "contaminated" surgical procedures.

The methodological quality of cluster randomised controlled trials for managing tropical parasitic disease: a review of trials published from 1998 to 2007.

The aim of this review was to assess the methodological quality of cluster randomised controlled trials (CRCT) for the management of tropical parasitic disease published between 1998 and 2007. A literature survey was conducted using Medline for CRCTs of interventions aimed at managing any one of the six major tropical parasitic diseases: malaria, leishmaniasis, lymphatic filariasis, onchocerciasis, schistosomiasis and trypanosomiasis (Chagas disease). Information was extracted from the published articles in order that, for each trial, categorical responses could be made to a pre-specified list of 12 questions concerning issues relating to the methodological quality of the trial, including choice of design, generalisability, baseline assessment, blinding, use or non-use of a matched design, and accounting for the intraclass correlation in both design and analysis.

The relationship between progression-free and post-progression survival in treating four types of metastatic cancer.

Context: A number of authors have found that there exists a positive relationship between progression-free survival and overall survival in clinical trials of cancer treatments for particular types of metastatic cancer. However, such an outcome is consistent with an increase in progression-free survival generally leading to an increase, a decrease or no change in survival following disease progression (post-progression survival) and which of these theories is valid has yet to be thoroughly investigated.

Objective: To test theories of this nature in relation to the use of chemotherapy in treating four different types of metastatic cancer by performing a systematic search of published clinical trials.