Clinical trials : journal of the Society for Clinical Trials
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Insufficient blinding of persons involved in randomized clinical trials is associated with bias. The appraisal of the risk of bias is difficult without adequate information in trial reports. ⋯ The blinding status of key trial persons was incompletely reported in most randomized clinical trials. Unreported blinding may be frequent, but one of five 'double blind' trials did not blind either patients, treatment providers or data collectors. Authors, referees, and journal editors could improve the completeness of reporting of blinding, eg, by adhering to the CONSORT statement. It is inappropriate to presume blinding of key trial persons based only on the ambiguous term 'double blind'.
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Economic outcomes are now included in many contemporary randomized trials and provide an additional dimension to the assessment of interventions. Economic data collection and analysis pose several methodologic challenges, however. ⋯ Economic outcomes can be measured alongside clinical outcomes in randomized trial. While the use of cost-effectiveness models falls outside the strictly empirical, within-trial analysis framework that is embraced by most clinical trialists, it provides an explicit approach to assessing whether the intervention under study provides a clinically meaningful improvement in outcome that is worthwhile.
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Comparative Study
Comparing an experimental agent to a standard agent: relative merits of a one-arm or randomized two-arm Phase II design.
Phase II clinical trials in cancer are used to assess whether a new agent has sufficiently promising efficacy to proceed on to a larger definitive study comparing the new agent to a standard agent. ⋯ We find that a one-arm design is preferred for small sample sizes, but a two-arm design may be preferred with larger sample sizes or if the uncertainty in the historical response rates is large.
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In order to make meaningful cross-cultural or cross-linguistic comparisons of health-related quality of life (HRQL) or to pool international research data, it is essential to create unbiased measures that can detect clinically important differences. When HRQL scores differ between cultural/linguistic groups, it is important to determine whether this reflects real group differences, or is the result of systematic measurement variability. ⋯ Enhanced methodologies are needed to differentiate trivial from substantive differential item functioning. Systematic variability in HRQL across different groups can be evaluated for its effect upon clinical trial results; a practice recommended when data are pooled across cultural or linguistic groups to make conclusions about treatment effects.