Contemporary clinical trials
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Contemp Clin Trials · Sep 2008
Predictive checking for Bayesian interim analyses in clinical trials.
Bayesian methodologies have been used for interim analyses of clinical trial data. In Bayesian interim analyses, decisions regarding the continuation of a trial are guided by a Bayesian model or indices, e.g., the predictive probability derived from it that specifies the conditions under which the clinical trial results might be judged sufficiently convincing to allow early stopping. ⋯ In this paper we describe the use of both prior- and posterior- predictive checking approaches as a diagnostic tool for assessing the reliability of the model or indices on which the decision making is based. The proposed approach is illustrated with three examples, one of which is a simulation.
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Contemp Clin Trials · Sep 2008
Chinese authors do need CONSORT: reporting quality assessment for five leading Chinese medical journals.
Only a few Chinese medical journals have recommended CONSORT in their "Instruction for authors or Guide for authors". This study aims to evaluate the reporting quality of randomized controlled trials (RCTs) published in the five leading Chinese medical journals indexed by MEDLINE. ⋯ The reporting quality of RCTs published in the five leading Chinese medical journals is low. Chinese journals should adopt the CONSORT statement to improve the reporting quality of Chinese randomized controlled trials.
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Contemp Clin Trials · Sep 2008
Estimating the proportion of studies missing for meta-analysis due to publication bias.
A potential problem with meta-analysis concerns missing studies due to publication bias. This paper focuses on one subtype of publication bias, namely selection bias (studies with unfavorable outcomes tend to be suppressed), wherein the main interest is in determining the proportion of unpublished studies. ⋯ The new method is very simple and its results are comparable to other meta-analytic methods. However, in contrast to existing methods, it can be applied to the study-specific outcomes alone.
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We propose a Bayesian approach to monitor clinical trials with clustered binary outcomes using multivariate probit models. Our monitoring is based on the calculated probability of the reduced incidence rate using a new treatment compared with the standard treatment greater than a target improvement under different prior scenarios for the treatment effect. We develop a Bayesian sampling algorithm for posterior inference allowing missing values in the outcomes. We illustrate our method using a published early trail of inhaled nitric oxide therapy in premature infants.
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Contemp Clin Trials · Sep 2008
Qualitative research to improve RCT recruitment: issues arising in establishing research collaborations.
Strategies to improve recruitment to RCTs (randomised controlled trials) are limited. The ProtecT (Prostate testing for cancer and Treatment) study successfully developed a complex intervention based on qualitative research methods to increase recruitment rates. The Quartet study (Qualitative Research to Improve Recruitment to RCTs) was established to evaluate whether the ProtecT qualitative methods could be transferred into other RCTs. This paper reports on the barriers and facilitators in setting up these collaborations. ⋯ The Quartet study established collaborations with a range of RCTs and gained valuable insights for future collaborations between qualitative researchers and RCTs. Qualitative research methods need to be included at the feasibility stage of a RCT or fully integrated into the RCT, as in the ProtecT study, with routine audio-recording for monitoring and training purposes. Quartet-like collaborations could then be established without delay, and recruitment processes of RCTs could become transparent, monitored and improved.