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Block Randomization (block + randomization)
Selected Abstracts44-55-66-PM, a Mnemonic That Improves Retention of the Ottawa Ankle and Foot Rules: A Randomized Controlled TrialACADEMIC EMERGENCY MEDICINE, Issue 8 2010FRCPC, Jocelyn Gravel MD ACADEMIC EMERGENCY MEDICINE 2010; 17:859,864 © 2010 by the Society for Academic Emergency Medicine Abstract Objectives:, Studies have suggested that poor knowledge of the Ottawa Ankle Rules (OAR) limits its clinical impact. This study evaluated the ability of a mnemonic to improve knowledge of the OAR. Methods:, This was a single-blind randomized controlled trial performed among residents and medical students doing a pediatric emergency medicine rotation. At baseline, all participants were tested for their baseline knowledge of the OAR. The intervention was a standardized information sheet providing a mnemonic of the OAR (44-55-66-PM), while control subjects received its classic description. Block randomization (medical student vs. type of resident) was used. Each participant answered the same questionnaire at the end of rotation (3 weeks later) and via a Web-based survey 5 to 9 months postrandomization. Main outcome measures were knowledge of the components of the ankle rule based on a 13-item criterion grid and the foot rule based on a 10-item criterion grid. All questionnaires were marked at the end of the study by two reviewers blinded to the randomization. Discrepancies in final scores were resolved by consensus. Student's t-test was performed to compare mean scores on the evaluation between groups using an intention-to-treat approach. Results:, Among the 206 eligible participants, 96 medical students and 94 residents were recruited and agreed to participate. Primary outcomes were measured in 95% of the participants at 3 weeks postrandomization and in 72% on the long-term follow-up. Participants in both groups were similar with regard to baseline characteristics and prior knowledge of the OAR. Both groups showed improvement in their knowledge of the rule during the study period. At mid-term, knowledge of the OAR was similar for the ankle components (score for mnemonic 10.9; control 10.2; 95% confidence interval [CI] for difference = ,0.3 to 1.7) and for the foot (mnemonic 7.6 vs. control 7.5; 95% CI for difference = ,0.7 to 0.9). On the long term, randomization to the mnemonic was associated with a better knowledge of the OAR as demonstrated by a higher score for the ankle component (mnemonic 10.1 vs. control 8.9; 95% CI for difference = 0.6 to 1.8) and for the foot (mnemonic 7.8 vs. control 6.5; 95% CI for difference = 0.8 to 1.9). Conclusions:, Mid-term knowledge of the OAR drastically improved for all participants of the study. The use of the mnemonic 44-55-66-PM was associated with a better long-term knowledge of the OAR among medical students and residents. The improvement in knowledge of the OAR among the control group highlights the importance of using controlled trials for studies evaluating knowledge transfer. [source] Music and its effect on anxiety in short waiting periods: a critical appraisalJOURNAL OF CLINICAL NURSING, Issue 2 2005Marie Cooke PhD Aims and objectives., This paper undertakes a critical appraisal of the methodological issues associated with studies that have investigated the extent to which music decreased the anxiety experienced by patients in short-term waiting periods such as day surgery. Background., Investigations and surgery undertaken on a day basis have significantly increased in number over the last decade. Music has been evaluated as an appropriate nursing intervention in relation to pain, discomfort and anxiety in a number of clinical settings but its usefulness for decreasing anxiety in short-term waiting periods such as day surgery is only beginning to be understood. Conclusion., A number of methodological limitations are identified by this critical review, particularly in relation to the design of research studies. Recommendations to strengthen research in this area are suggested and include (i) describing methods clearly and with detail to allow assessment of the validity and rigour of study results; (ii) using permuted block randomization; (iii) recruiting from a variety of surgical procedures and cultural groups; and (iv) standardizing the health care provided during waiting period. Relevance to clinical practice., Music as a simple and cost-effective intervention to reduce the anxiety experienced in limited time periods will have enormous impact on clinical practice where patients wait and undergo invasive investigations, procedures or surgery. However, the evidence of its utility in these unique environments is only beginning to emerge and this critical review provides a basis for considerations for future research. [source] Balancing treatment allocations by clinician or center in randomized trials allows unacceptable levels of treatment predictionJOURNAL OF EVIDENCE BASED MEDICINE, Issue 3 2009Robert K Hills Abstract Objective Randomized controlled trials are the standard method for comparing treatments because they avoid the selection bias that might arise if clinicians were free to choose which treatment a patient would receive. In practice, allocation of treatments in randomized controlled trials is often not wholly random with various ,pseudo-randomization' methods, such as minimization or balanced blocks, used to ensure good balance between treatments within potentially important prognostic or predictive subgroups. These methods avoid selection bias so long as full concealment of the next treatment allocation is maintained. There is concern, however, that pseudo-random methods may allow clinicians to predict future treatment allocations from previous allocation history, particularly if allocations are balanced by clinician or center. We investigate here to what extent treatment prediction is possible. Methods Using computer simulations of minimization and balanced block randomizations, the success rates of various prediction strategies were investigated for varying numbers of stratification variables, including the patient's clinician. Results Prediction rates for minimization and balanced block randomization typically exceed 60% when clinician is included as a stratification variable and, under certain circumstances, can exceed 80%. Increasing the number of clinicians and other stratification variables did not greatly reduce the prediction rates. Without clinician as a stratification variable, prediction rates are poor unless few clinicians participate. Conclusion Prediction rates are unacceptably high when allocations are balanced by clinician or by center. This could easily lead to selection bias that might suggest spurious, or mask real, treatment effects. Unless treatment is blinded, randomization should not be balanced by clinician (or by center), and clinician,center effects should be allowed for instead by retrospectively stratified analyses. [source] Use of simulation to compare the performance of minimization with stratified blocked randomizationPHARMACEUTICAL STATISTICS: THE JOURNAL OF APPLIED STATISTICS IN THE PHARMACEUTICAL INDUSTRY, Issue 4 2009Robert Toorawa Abstract Minimization is an alternative method to stratified permuted block randomization, which may be more effective at balancing treatments when there are many strata. However, its use in the regulatory setting for industry trials remains controversial, primarily due to the difficulty in interpreting conventional asymptotic statistical tests under restricted methods of treatment allocation. We argue that the use of minimization should be critically evaluated when designing the study for which it is proposed. We demonstrate by example how simulation can be used to investigate whether minimization improves treatment balance compared with stratified randomization, and how much randomness can be incorporated into the minimization before any balance advantage is no longer retained. We also illustrate by example how the performance of the traditional model-based analysis can be assessed, by comparing the nominal test size with the observed test size over a large number of simulations. We recommend that the assignment probability for the minimization be selected using such simulations. Copyright © 2008 John Wiley & Sons, Ltd. [source] Balancing treatment allocations by clinician or center in randomized trials allows unacceptable levels of treatment predictionJOURNAL OF EVIDENCE BASED MEDICINE, Issue 3 2009Robert K Hills Abstract Objective Randomized controlled trials are the standard method for comparing treatments because they avoid the selection bias that might arise if clinicians were free to choose which treatment a patient would receive. In practice, allocation of treatments in randomized controlled trials is often not wholly random with various ,pseudo-randomization' methods, such as minimization or balanced blocks, used to ensure good balance between treatments within potentially important prognostic or predictive subgroups. These methods avoid selection bias so long as full concealment of the next treatment allocation is maintained. There is concern, however, that pseudo-random methods may allow clinicians to predict future treatment allocations from previous allocation history, particularly if allocations are balanced by clinician or center. We investigate here to what extent treatment prediction is possible. Methods Using computer simulations of minimization and balanced block randomizations, the success rates of various prediction strategies were investigated for varying numbers of stratification variables, including the patient's clinician. Results Prediction rates for minimization and balanced block randomization typically exceed 60% when clinician is included as a stratification variable and, under certain circumstances, can exceed 80%. Increasing the number of clinicians and other stratification variables did not greatly reduce the prediction rates. Without clinician as a stratification variable, prediction rates are poor unless few clinicians participate. Conclusion Prediction rates are unacceptably high when allocations are balanced by clinician or by center. This could easily lead to selection bias that might suggest spurious, or mask real, treatment effects. Unless treatment is blinded, randomization should not be balanced by clinician (or by center), and clinician,center effects should be allowed for instead by retrospectively stratified analyses. [source] | ||||||||||