Clinical trials : journal of the Society for Clinical Trials
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Many clinical trial designs are impractical for community-based clinical intervention trials. Stepped wedge trial designs provide practical advantages, but few descriptions exist of their clinical implementational features, statistical design efficiencies, and limitations. ⋯ Stepped wedge trial designs that intervene in small clusters across longer periods can provide enhanced power to evaluate comparative effectiveness, while offering practical implementation advantages in geographic stratification, temporal change, use of existing data, and resource distribution. Current population estimates were used; however, models may not reflect actual event rates during the trial. In addition, temporal or spatial heterogeneity can bias treatment effect estimates.
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Participants in health research studies typically express interest in receiving the results from the studies in which they participate. However, participants' preferences and experiences related to receiving the results are not well understood. In general, the existing studies have had relatively small sample sizes and typically address specific and often sensitive issues within targeted populations. ⋯ We present findings from a survey assessing attitudes and experiences of a broad sample of respondents that addresses gaps in knowledge related to participants' preferences for receiving the results. The study's findings highlight the potential for inconsistency between respondents' expressed preferences to receive specific types of results via specific methods and researchers' unwillingness or inability to provide them. We present specific recommendations to shift the approach of new studies to investigate participants' preferences for receiving research results.
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Ensuring fidelity to a behavioral intervention implemented in nursing homes requires awareness of the unique considerations of this setting for research. The purpose of this article is to describe the goals of care cluster-randomized trial and the methods used to monitor and promote fidelity to a goals of care decision aid intervention delivered in nursing homes. ⋯ The methods we used for intervention fidelity allowed nursing home staff to implement a goals of care decision aid intervention for advanced dementia. Key supports for implementation included design features that aligned with nursing home practice, efficient staff training, and a structured guide for goals of care discussions between family decision-makers and staff. These approaches may be used to promote fidelity to behavioral interventions in future clinical trials.
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Factorial analyses of 2 × 2 trial designs are known to be problematic unless one can be sure that there is no interaction between the treatments (A and B). Instead, we consider non-factorial analyses of a factorial trial design that addresses clinically relevant questions of interest without any assumptions on the interaction. Primary questions of interest are as follows: (1) is A better than the control treatment C, (2) is B better than C, (3) is the combination of A and B (AB) better than C, and (4) is AB better than A, B, and C. ⋯ Factorial trial designs are an efficient way to evaluate two treatments, alone and in combination. In situations where a statistical interaction between the treatment effects cannot be assumed to be 0, simple non-factorial analyses are possible that directly assess the questions of interest without the zero interaction assumption.
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In testing for non-inferiority of anti-infective drugs, the primary endpoint is often the difference in the proportion of failures between the test and control group at a landmark time. The landmark time is chosen to approximately correspond to the qth historic quantile of the control group, and the non-inferiority margin is selected to be reasonable for the target level q. For designing these studies, a troubling issue is that the landmark time must be pre-specified, but there is no guarantee that the proportion of control failures at the landmark time will be close to the target level q. If the landmark time is far from the target control quantile, then the pre-specified non-inferiority margin may not longer be reasonable. Exact variable margin tests have been developed by Röhmel and Kieser to address this problem, but these tests can have poor power if the observed control failure rate at the landmark time is far from its historic value. ⋯ A substantial proportion of new anti-infective drugs being developed use non-inferiority tests in their development, and typically, a pre-specified landmark time and its associated difference margin are set at the design stage to match a specific target control quantile. If through changing standard of care or selection of a different population the target quantile for the control group changes from its historic value, then the appropriateness of the pre-specified margin at the landmark time may be questionable. Our proposed test avoids this problem by sampling until a pre-specified proportion of the controls have failed.