Controlled clinical trials
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Control Clin Trials · Apr 2000
Randomized Controlled Trial Clinical TrialImpact of the Hawthorne effect in a longitudinal clinical study: the case of anesthesia.
Clinical research can be influenced by many factors that are capable of invalidating results, and one of these factors is known as the Hawthorne effect: the mere awareness of being under observation can alter the way in which a person behaves. In experimental research this effect can be the undesired effect of the experiments themselves, and the stronger its presence, the greater it can influence the results. In anesthesia practice, owing to the particular emotional condition of a patient facing a surgical operation, the Hawthorne effect could be especially strong. ⋯ The size of the effect, as measured by the odds ratio, remains unchanged when controlling for potential confounding factors. The study has enabled us to demonstrate the presence of the Hawthorne effect in clinical research. Therefore, the Hawthorne effect should be acknowledged and accounted for in the design of a study and in the interpretation of results.
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Control Clin Trials · Aug 1998
Randomized Controlled Trial Multicenter Study Clinical TrialSystemic Corticosteroids in Chronic Obstructive Pulmonary Disease Exacerbations (SCCOPE): rationale and design of an equivalence trial. Veterans Administration Cooperative Trials SCCOPE Study Group.
The Systemic Corticosteroids in Chronic Obstructive Pulmonary Disease Exacerbations Trial (SCCOPE) was a randomized, double-blind, placebo-controlled, multicenter trial sponsored by the U. S. Department of Veterans Affairs Cooperative Studies Program. ⋯ The primary endpoint of the study was treatment failure, defined as death, intubation with mechanical ventilation, hospital readmission for COPD, or intensification of pharmacologic therapy. Secondary endpoints included length of hospital stay, changes in FEV1, and changes in dyspnea score. We also evaluated possible adverse effects from systemic corticosteroids.
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Control Clin Trials · Aug 1998
Randomized Controlled Trial Multicenter Study Clinical TrialRationale and design for the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) Trial.
The Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) Trial is a randomized, prospective, double-blind, parallel-group, two-arm, actively controlled, multicenter, international 5-year clinical trial involving 15,000 patients. CONVINCE will compare the incidence of fatal or nonfatal myocardial infarction (MI), fatal or nonfatal stroke, or cardiovascular-disease-related death in two antihypertensive treatment regimens. One treatment arm begins with controlled onset-extended release (COER)-verapamil, which has its major antihypertensive effect 6-12 hours after administration. ⋯ Although most patients switch from an established antihypertensive medication to randomized treatment, untreated patients with stages I-III hypertension (SBP between 140 and 190 or DBP between 90 and 110 mm Hg) are eligible. Outcomes are monitored by an independent Data and Safety Monitoring Board. Enrollment began during the third quarter of 1996, and follow-up is to be completed in the third quarter of 2002.
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Control Clin Trials · Feb 1998
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialStroke prevention trial in sickle cell anemia.
Stroke occurs in 7-8% of children with Sickle Cell Disease (Hb SS) and is a major cause of morbidity. Rates of recurrence have been reduced from 46-90% to less than 10% through chronic blood transfusions. Prevention of first stroke, however, would be preferable because even one stroke can cause irreversible brain injury. ⋯ The sample size is sufficient to detect 70% reduction in the primary endpoint at 90% power. This trial will determine if transfusion is effective in the primary prevention of stroke. Secondary aims may further the understanding of the effects of transfusion on the brain and guide future research into cerebrovascular disease in Hb SS.
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Control Clin Trials · Dec 1997
ReviewClinical trials with multiple outcomes: a statistical perspective on their design, analysis, and interpretation.
This article tackles both practical and statistical issues in the handling of multiple outcomes in clinical trials, with relevance to trial design, analysis, and reporting. Specific topics illustrated by examples include: the advantage of prespecifying priorities amongst outcomes and analyses, corrections for multiple significance testing and their limited value, problems with adverse event data, the use of a single global test of significance for clinically related outcomes, the use of a combined outcome for clinical event data, and the value of exploring interrelationships amongst outcomes. The problems in handling multiple outcomes are enhanced by trials being too small, dichotomous attitudes (is the trial "positive" or not?), obsession with p-values, and the manipulative instincts of human nature. While predeclarations of priorities in analysis and reporting of multiple outcomes are important in suppressing distortive claims, it would be unfortunate if too inflexible an approach suppressed unpredictable findings from being seriously considered.