Investigating the relationship between predictability and imbalance in minimisation : a simulation study

Peer reviewedPublisher PD

GS-2: A novel Broad-Spectrum agent for environmental microbial control

The environmental control of microbial pathogens currently relies on compounds that do not exert long-lasting activity on surfaces, are impaired by soil, and contribute to the growing problem of antimicrobial resistance. This study presents the scientific development and characterization of GS-2, a novel, water-soluble ammonium carboxylate salt of capric acid and L-arginine that demonstrates activity against a range of bacteria (particularly Gram-negative bacteria), fungi, and viruses. In real-world surface testing, GS-2 was more effective than a benzalkonium chloride disinfectant at reducing the bacterial load on common touch-point surfaces in a high-traffic building (average 1.6 vs. 32.6 CFUs recovered from surfaces 90 min after application, respectively). Toxicology testing in rats confirmed GS-2 ingredients were rapidly cleared and posed no toxicities to humans or animals. To enhance the time-kill against Gram-positive bacteria, GS-2 was compounded at a specific ratio with a naturally occurring monoterpenoid, thymol, to produce a water-based antimicrobial solution. This GS-2 with thymol formulation could generate a bactericidal effect after five minutes of exposure and a viricidal effect after 10 min of exposure. Further testing of the GS-2 and thymol combination on glass slides demonstrated that the compound retained bactericidal activity for up to 60 days. Based on these results, GS-2 and GS-2 with thymol represent a novel antimicrobial solution that may have significant utility in the long-term reduction of environmental microbial pathogens in a variety of settings

Recruitment to randomised trials : Strategies for Trial Enrolment and Participation Study. The STEPS study

Objectives: To identify factors associated with good and poor recruitment to multicentre trials. Data sources: Part A: database of trials started in or after 1994 and were due to end before 2003 held by the Medical Research Council and Health Technology Assessment Programmes. Part B: interviews with people playing a wide range of roles within four trials that their funders identified as ‘exemplars’. Part C: a large multicentre trial (the CRASH trial) of treatment for head injury. Review methods: The study used a number of different perspectives (‘multiple lenses’), and three components. Part A: an epidemiological review of a cohort of trials. Part B: case studies of trials that appeared to have particularly interesting lessons for recruitment. Part C: a single, in-depth case study to examine the feasibility of applying a businessorientated analytical framework as a reference model in future trials. Results: In the 114 trials found in Part A, less than one-third recruited their original target within the time originally specified, and around one-third had extensions. Factors observed more often in trials that recruited successfully were: having a dedicated trial manager, being a cancer or drug trial, and having interventions only available inside the trial. The most commonly reported strategies to improve recruitment were newsletters and mailshots, but it was not possible to assess whether they were causally linked to changes in recruitment. The analyses in Part B suggested that successful trials were those addressing clinically important questions at a timely point. The investigators were held in high esteem by the interviewees, and the trials were firmly grounded in existing clinical practices, so that the trial processes were not alien to clinical collaborators, and the results could be easily applicable to future practice. The interviewees considered that the needs of patients were well served by participation in the trials. Clinical collaborators particularly appreciated clear delineation of roles, which released them from much of the workload associated with trial participation. There was a strong feeling from interviewees that they were proud to be part of a successful team. This pride fed into further success. Good groundwork and excellent communications across many levels of complex trial structures were considered to be extremely important, including training components for learning about trial interventions and processes, and team building. All four trials had faced recruitment problems, and extra insights into the working of trials were afforded by strategies invoked to address them. The process of the case study in Part C was able to draw attention to a body of research and practice in a different discipline (academic business studies). It generated a reference model derived from a combination of business theory and work within CRASH. This enabled identification of weaker managerial components within CRASH, and initiatives to strengthen them. Although it is not clear, even within CRASH, whether the initiatives that follow from developing and applying the model will be effective in increasing recruitment or other aspects of the success of the trial, the reference model could provide a template, with potential for those managing other trials to use or adapt it, especially at foundation stages. The model derived from this project could also be used as a diagnostic tool if trials have difficulties and hence as a basis for deciding what type of remedial action to take. It may also be useful for auditing the progress of trials, such as during external review. Conclusions: While not producing sufficiently definitive results to make strong recommendations, the work here suggests that future trials should consider the different needs at different phases in the life of trials, and place greater emphasis on ‘conduct’ (the process of actually doing trials). This implies learning lessons from successful trialists and trial managers, with better training for issues relating to trial conduct. The complexity of large trials means that unanticipated difficulties are highly likely at some time in every trial. Part B suggested that successful trials were those flexible and robust enough to adapt to unexpected issues. Arguably, the trialists should also expect agility from funders within a proactive approach to monitoring ongoing trials. Further research into different recruitment patterns (including ‘failures’) may help to clarify whether the patterns seen in the ‘exemplar’ trials differ or are similar. The reference model from Part C needs to be further considered in other similar and different trials to assess its robustness. These and other strategies aimed at increasing recruitment and making trials more successful need to be formally evaluated for their effectiveness in a range of trials.Not peer reviewedPublisher PD

A school-based social-marketing intervention to promote sexual health in English secondary schools: the Positive Choices pilot cluster RCT

Background: The UK still has the highest rate of teenage births in western Europe. Teenagers are also the age group most likely to experience unplanned pregnancy, with around half of conceptions in those aged < 18 years ending in abortion. After controlling for prior disadvantage, teenage parenthood is associated with adverse medical and social outcomes for mothers and children, and increases health inequalities. This study evaluates Positive Choices (a new intervention for secondary schools in England) and study methods to assess the value of a Phase III trial. Objectives: To optimise and feasibility-test Positive Choices and then conduct a pilot trial in the south of England assessing whether or not progression to Phase III would be justified in terms of prespecified criteria. Design: Intervention optimisation and feasibility testing; pilot randomised controlled trial. Setting: The south of England: optimisation and feasibility-testing in one secondary school; pilot cluster trial in six other secondary schools (four intervention, two control) varying by local deprivation and educational attainment. Participants: School students in year 8 at baseline, and school staff. Interventions: Schools were randomised (1 : 2) to control or intervention. The intervention comprised staff training, needs survey, school health promotion council, year 9 curriculum, student-led social marketing, parent information and review of school/local sexual health services. Main outcome measures: The prespecified criteria for progression to Phase III concerned intervention fidelity of delivery and acceptability; successful randomisation and school retention; survey response rates; and feasible linkage to routine administrative data on pregnancies. The primary health outcome of births was assessed using routine data on births and abortions, and various self-reported secondary sexual health outcomes. Data sources: The data sources were routine data on births and abortions, baseline and follow-up student surveys, interviews, audio-recordings, observations and logbooks. Results: The intervention was optimised and feasible in the first secondary school, meeting the fidelity targets other than those for curriculum delivery and criteria for progress to the pilot trial. In the pilot trial, randomisation and school retention were successful. Student response rates in the intervention group and control group were 868 (89.4%) and 298 (84.2%), respectively, at baseline, and 863 (89.0%) and 296 (82.0%), respectively, at follow-up. The target of achieving ≥ 70% fidelity of implementation of essential elements in three schools was achieved. Coverage of relationships and sex education topics was much higher in intervention schools than in control schools. The intervention was acceptable to 80% of students. Interviews with staff indicated strong acceptability. Data linkage was feasible, but there were no exact matches for births or abortions in our cohort. Measures performed well. Poor test–retest reliability on some sexual behaviour measures reflected that this was a cohort of developing adolescents. Qualitative research confirmed the appropriateness of the intervention and theory of change, but suggested some refinements. Limitations: The optimisation school underwent repeated changes in leadership, which undermined its participation. Moderator analyses were not conducted as these would be very underpowered. Conclusion: Our findings suggest that this intervention has met prespecified criteria for progression to a Phase III trial. Future work: Declining prevalence of teenage pregnancy suggests that the primary outcome in a full trial could be replaced by a more comprehensive measure of sexual health. Any future Phase III trial should have a longer lead-in from randomisation to intervention commencement

Contamination in trials of educational interventions

Objectives: To consider the effects of contamination on the magnitude and statistical significance (or precision) of the estimated effect of an educational intervention, to investigate the mechanisms of contamination, and to consider how contamination can be avoided. Data sources: Major electronic databases were searched up to May 2005. Methods: An exploratory literature search was conducted. The results of trials included in previous relevant systematic reviews were then analysed to see whether studies that avoided contamination resulted in larger effect estimates than those that did not. Experts’ opinions were elicited about factors more or less likely to lead to contamination. We simulated contamination processes to compare contamination biases between cluster and individually randomised trials. Statistical adjustment was made for contamination using Complier Average Causal Effect analytic methods, using published and simulated data. The bias and power of cluster and individually randomised trials were compared, as were Complier Average Causal Effect, intention-to-treat and per protocol methods of analysis. Results: Few relevant studies quantified contamination. Experts largely agreed on where contamination was more or less likely. Simulation of contamination processes showed that, with various combinations of timing, intensity and baseline dependence of contamination, cluster randomised trials might produce biases greater than or similar to those of individually randomised trials. Complier Average Causal Effect analyses produced results that were less biased than intention-to-treat or per protocol analyses. They also showed that individually randomised trials would in most situations be more powerful than cluster randomised trials despite contamination. Conclusions: The probability, nature and process of contamination should be considered when designing and analysing controlled trials of educational interventions in health. Cluster randomisation may or may not be appropriate and should not be uncritically assumed always to be a solution. Complier Average Causal Effect models are an appropriate way to adjust for contamination if it can be measured. When conducting such trials in future, it is a priority to report the extent, nature and effects of contamination.We are grateful to the National Health Service Research and Development National Coordinating Centre for Research Methodology for funding this research

Marketing and clinical trials: a case study.

BACKGROUND: Publicly funded clinical trials require a substantial commitment of time and money. To ensure that sufficient numbers of patients are recruited it is essential that they address important questions in a rigorous manner and are managed well, adopting effective marketing strategies. METHODS: Using methods of analysis drawn from management studies, this paper presents a structured assessment framework or reference model, derived from a case analysis of the MRC's CRASH trial, of 12 factors that may affect the success of the marketing and sales activities associated with clinical trials. RESULTS: The case study demonstrates that trials need various categories of people to buy in - hence, to be successful, trialists must embrace marketing strategies to some extent. CONCLUSION: The performance of future clinical trials could be enhanced if trialists routinely considered these factors

Intracluster correlation coefficients in cluster randomized trials: empirical insights into how should they be reported

BACKGROUND: Increasingly, researchers are recognizing that there are many situations where the use of a cluster randomized trial may be more appropriate than an individually randomized trial. Similarly, the need for appropriate standards of reporting of cluster trials is more widely acknowledged. METHODS: In this paper, we describe the results of a survey to inform the appropriate reporting of the intracluster correlation coefficient (ICC) – the statistical measure of the clustering effect associated with a cluster randomized trial. RESULTS: We identified three dimensions that should be considered when reporting an ICC – a description of the dataset (including characteristics of the outcome and the intervention), information on how the ICC was calculated, and information on the precision of the ICC. CONCLUSIONS: This paper demonstrates the development of a framework for the reporting of ICCs. If adopted into routine practice, it has the potential to facilitate the interpretation of the cluster trial being reported and should help the development of new trials in the area

What influences recruitment to randomised controlled trials? A review of trials funded by two UK funding agencies.

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.BACKGROUND: A commonly reported problem with the conduct of multicentre randomised controlled trials (RCTs) is that recruitment is often slower or more difficult than expected, with many trials failing to reach their planned sample size within the timescale and funding originally envisaged. The aim of this study was to explore factors that may have been associated with good and poor recruitment in a cohort of multicentre trials funded by two public bodies: the UK Medical Research Council (MRC) and the Health Technology Assessment (HTA) Programme. METHODS: The cohort of trials was identified from the administrative databases held by the two funding bodies. 114 trials that recruited participants between 1994 and 2002 met the inclusion criteria. The full scientific applications and subsequent trial reports submitted by the trial teams to the funders provided the principal data sources. Associations between trial characteristics and recruitment success were tested using the Chi-squared test, or Fisher's exact test where appropriate. RESULTS: Less than a third (31%) of the trials achieved their original recruitment target and half (53%) were awarded an extension. The proportion achieving targets did not appear to improve over time. The overall start to recruitment was delayed in 47 (41%) trials and early recruitment problems were identified in 77 (63%) trials. The inter-relationship between trial features and recruitment success was complex. A variety of strategies were employed to try to increase recruitment, but their success could not be assessed. CONCLUSION: Recruitment problems are complex and challenging. Many of the trials in the cohort experienced recruitment difficulties. Trials often required extended recruitment periods (sometimes supported by additional funds). While this is of continuing concern, success in addressing the trial question may be more important than recruitment alone.Published versio

Financial considerations in the conduct of multi-centre randomised controlled trials: evidence from a qualitative study.

National Coordinating Centre for Research Methodology; Medical Research Council, UK Department of Health; Chief Scientist OfficeNot peer reviewedPublisher PD