Controlled clinical trials
-
Control Clin Trials · Apr 2003
Comparative Study Clinical Trial Controlled Clinical TrialPatient compliance with paper and electronic diaries.
Paper diaries are commonly used in health care and clinical research to assess patient experiences. There is concern that patients do not comply with diary protocols, possibly invalidating the benefit of diary data. Compliance with paper diaries was examined with a paper diary and with an electronic diary that incorporated compliance-enhancing features. ⋯ For the electronic diary, the actual compliance rate was 94%. In summary, participants with chronic pain enrolled in a study for research were not compliant with paper diaries but were compliant with an electronic diary with enhanced compliance features. The findings call into question the use of paper diaries and suggest that electronic diaries with compliance-enhancing features are a more effective way of collecting diary information.
-
Control Clin Trials · Dec 2003
Randomized Controlled Trial Clinical TrialAn international multicenter protocol to assess the single and combined benefits of antiemetic interventions in a controlled clinical trial of a 2x2x2x2x2x2 factorial design (IMPACT).
For various diseases clinicians have to combine different drugs or interventions when a single drug or intervention does not lead to satisfactory results. However, quantifying the relative benefit of certain drugs or interventions when given alone and in combination under controlled conditions requires a complex factorial design. This paper describes such a method applied to a large multicenter trial for the prevention of postoperative nausea and vomiting (PONV), which may be of great interest for other specialties. ⋯ Eligible patients are adults scheduled for elective surgery under general anesthesia with an increased risk for PONV so that the expected incidence in the control group (with none of the six antiemetic interventions) is approximately 60%. In order to allow analyses for up to three factor interactions, a sample size was estimated to be in the range of approximately 5000 patients. To the best of our knowledge this is the first randomized controlled trial of a six-way factorial design that may serve as an example for numerous other medical specialties.
-
Control Clin Trials · Oct 2003
Randomized Controlled Trial Clinical TrialLook AHEAD (Action for Health in Diabetes): design and methods for a clinical trial of weight loss for the prevention of cardiovascular disease in type 2 diabetes.
Overweight and obesity are major contributors to both type 2 diabetes and cardiovascular disease (CVD). Moreover, individuals with type 2 diabetes who are overweight or obese are at particularly high risk for CVD morbidity and mortality. Although short-term weight loss has been shown to ameliorate obesity-related metabolic abnormalities and CVD risk factors, the long-term consequences of intentional weight loss in overweight or obese individuals with type 2 diabetes have not been adequately examined. ⋯ The primary study outcome is time to incidence of a major CVD event. The study is designed to provide a 0.90 probability of detecting an 18% difference in major CVD event rates between the two groups. Other outcomes include components of CVD risk, cost and cost-effectiveness, diabetes control and complications, hospitalizations, intervention processes, and quality of life.
-
Control Clin Trials · Apr 2003
Randomized Controlled Trial Clinical TrialElicitation of prior distributions for a phase III randomized controlled trial of adjuvant therapy with surgery for hepatocellular carcinoma.
A randomized, controlled clinical trial of radioactive iodine tagged with lipiodol in patients with resected hepatocellular carcinoma was criticized for its early stopping and resulting small sample size. To clarify its results, a new, larger multicenter trial was therefore proposed. ⋯ They can also be used in Bayesian analyses, both at the interim stage(s) as well as at the end of the trial. We illustrate these analyses, assuming that the data resulting from the new trial was the same as that obtained in the earlier trial when it was stopped.
-
Control Clin Trials · Oct 2003
ReviewA group sequential, response-adaptive design for randomized clinical trials.
There has been considerable methodological research on response-adaptive designs for clinical trials but they have seldom been used in practice. The many reasons for this are summarized in an article by Rosenberger and Lachin, but the two main reasons generally cited are logistical difficulties and the potential for bias due to selection effects, "drift" in patient characteristics or risk factors over time, and other sources. Jennison and Turnbull consider a group sequential, response-adaptive design for continuous outcome variables that partially addresses these concerns while at the same time allowing for early stopping. ⋯ Limitations, such as the impact of delays in observing outcomes, are discussed, as well as areas for further research. We conclude that responsive adaptive designs may be useful for some purposes, particularly in the presence of large treatment effects, although allowing early stopping minimizes the benefits. If such a design is undertaken, the randomization and analysis should be stratified in order to avoid bias due to time trends.