The choice of a balanced allocation method for a clinical trial in otitis media with effusion

Zielhuis, G. A.; Straatman, Huub; Hof-Grootenboer, A. E. Van 'T; Lier, H. J. J. Van; Rach, Gerold H.; Broek, Paul van den

doi:10.1002/sim.4780090306

Cited by 67 publications

(40 citation statements)

References 12 publications

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“…This difference is significant (Fisher's exact test ƒ* = (). () 12). The analysis of the patients' answers to the HSCL (Tableó) shows that the patients who described an altered sensation in the lower lip before treatment had a significantly higher HSCL score than those who did not ( Mann Whitney U test).…”

Section: Resultsmentioning

confidence: 99%

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Patients' perception of sensory disturbances of the mental nerve before and after implant surgery: a prospective study of 110 patients

Wismeijer

Waas

Vermeeren

et al. 1997

British Journal of Oral and Maxillofacial Surgery

181

131

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SUMMARY. In a randomized controlled clinical trial 110 edentulous patients with severe mandibular bone loss have been treated with ITI-dentai implants using three different treatment strategies: (1) a mandibular overdenture supported by two implants with bail attachments, (2) two implants with an interconnecting bar or (3) by four interconnected implants.As implant surgery involves elevation of the mucoperiosteum, bone remodelling at the implant site and insertion of implants close to the mental foramen, altered sensations of the mental nerve caused by the surgery are to be expected. An altered sensation of the lower lip can also be caused by pressure of an ill-fitting lower denture on the mental foramen, or in the case of severe bone loss of the alveolar ridge, on the alveolar nerve itself.This article presents the results of the patients' perception of the sensation of their lower lip before, 10 days after and 16 months after implant surgery in the mandible. It shows that 25% of the patients describe a sensory disturbance before treatment. This 25% also showed high scores on the Hopkins Symptoms Check List indicating a tendency to somatize complaints. Eleven percent of the patients report a sensory disturbance in the lower lip 10 days after surgery. Ten percent report a sensory disturbance 16 months after surgery of which one third also reported a disturbance before the treatment.This implies the risk of a sensory disturbance of the lower lip to be a possible complication after implant surgery. Therefore patients must be informed about this phenomenon before treatment.

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Section: Resultsmentioning

confidence: 99%

“…The mean (SD) score was 5.9 (3.1). The reference scale for normal people meaning here non-psychiatric and non-( psychosom atic has a scoring range from 0 to 12 and a mean scoring bracket has been set between 1 and 3. A high score is defined between 3 and 6 and a very high score is 7 and above.…”

Section: Resultsmentioning

confidence: 99%

Patients' perception of sensory disturbances of the mental nerve before and after implant surgery: a prospective study of 110 patients

Wismeijer

Waas

Vermeeren

et al. 1997

British Journal of Oral and Maxillofacial Surgery

181

131

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“…We started the minimization method with simple randomization of the first 10 patients, a strategy that is often used to prevent guessing of assignments [13]. We carried out dynamic block randomization as follows.…”

Section: Methodsmentioning

confidence: 99%

Comparison of dynamic block randomization and minimization in randomized trials: a simulation study

Xiao¹,

Lavori

Wilson

et al. 2011

Clinical Trials

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Background Minimizing the imbalance of key baseline covariates between treatments is known to be very important to the precision of the estimate of treatment effect in clinical research. Dynamic randomization allocation techniques have been used to achieve balance across multiple baseline characteristics. However, empirical data are limited on how these techniques compare in terms of balance and efficiency. We are motivated by a newly funded randomized controlled trial, in which we have the option of choosing between two methods of randomization at the subject level: (1) randomizing individual subjects consecutively as they are enrolled, using Pocock and Simon’s minimization method, and (2) simultaneously randomizing blocks of subjects once all subjects in a block have been enrolled, using a balance algorithm originally developed for cluster randomized trials. Purpose To compare dynamic block randomization and minimization in terms of balance on baseline covariates and statistical efficiency. Simple randomization was included as a reference. Methods A simulation study using data from a previous randomized controlled trial was conducted to compare balance statistics and the accuracy and power of hypothesis testing among the randomization methods. Results Dynamic block randomization consistently produced the best balance and highest power for various sample and treatment effect sizes, even after post-adjustment of the pre-specified baseline covariates in all three methods. Consistent with previous reports, minimization performed better in balance and power than simple randomization; however, the differences were noticeably smaller compared to those between dynamic block randomization and simple randomization. Limitations In this simulation study, we considered three sample sizes and two block sizes for a two-arm randomized trial. We assumed no interactions among the multiple baseline covariates. It is necessary to evaluate how the results may vary when the simulation conditions are changed before drawing broader conclusions regarding comparisons between the randomization methods. Conclusions This study demonstrates that dynamic block randomization outperforms minimization with regard to achieving balance and maximizing efficiency. Nevertheless, the differences across the three randomization strategies are modest. The statistical advantages associated with dynamic block randomization need to be considered in relation to the planned sample size and the practical issues for its implementation in deciding the preferred method of randomization for a given trial (e.g., the time required to accrue blocks of subjects of adequate size as balanced against the need to commence intervention/treatment immediately in those randomized to that experimental condition).

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“…During the first 13 weeks after implantation of a Synchro-Med programmable pump, the patients were randomly assigned to either baclofen (n=12) or a placebo (n=10). A balancing procedure was used to allocate the patients to the two conditions to achieve an equal distribution of patient characteristics with a potential effect on treatment outcomes over the two groups 15. The balancing criteria were age, sex, and aetiology of spasticity.…”

Section: Methodsmentioning

confidence: 99%

Effect of intrathecal baclofen delivered by an implanted programmable pump on health related quality of life in patients with severe spasticity

Middel

Kuipers-Upmeijer

Bouma

et al. 1997

Journal of Neurology, Neurosurgery & Psychiatry

113

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Objectives-To compare clinical eVectiveness and health related quality of life in patients with severe spasticity who received intrathecal baclofen or a placebo. Methods-In a double blind, randomised, multicentre trial 22 patients were followed up during 13 weeks and subsequently included in a 52 week observational longitudinal study. Patients were those with chronic, disabling spasticity who did not respond to maximum doses of oral baclofen, dantrolene, and tizanidine. After implantation of a programmable pump patients were randomly assigned to placebo or baclofen infusion for 13 weeks. After 13 weeks all patients received baclofen. Clinical eYcacy was assessed by the Ashworth scale, spasm score, and self reported pain, and health related quality of life by the sickness impact profile (SIP) and the Hopkins symptom checklist (HSCL). Results-At three months the scores of the placebo and baclofen group diVered slightly for the spasm score (eVect size=0.20) and substantially for the Ashworth scale (eVect size=1.40) and pain score (eVect size=0.94); health related quality of life showed no significant diVerences. Three months after implantation the baclofen group showed a significant, substantial improvement on the SIP "physical health", "mental health", "mobility", and "sleep and rest" subscales and on the HSCL mental health scale; patients receiving placebo showed no change. After one year of baclofen treatment significant (P<0.05) improvement was found on the SIP dimensions "mobility" and "body care and movement" with moderate eVect sizes. Improvement on the SIP subscale "physical health" (P<0.05; eVect size 0.86), the SIP overall score (without "ambulation"), and the "physical health" and overall scale of the HSCL was also significant, with eVect sizes >0.80. Changes in health related behaviour were noted for "sleep and rest" and "recreation and pastimes" (P<0.01, P<0.05; eVect size 0.95 and 0.63, respectively). Psychosocial behaviour showed no improvement. Conclusions-Intrathecal baclofen delivered by an implanted, programmable pump resulted in improved self reported quality of life as assessed by the SIP, and HSCL physical health dimensions also suggest improvement. (J Neurol Neurosurg Psychiatry 1997;63:204-209) Keywords: baclofen; health related quality of life; clinical outcomes Continuous intrathecal baclofen infusion via a subcutaneously implanted programmable pump has been used in the treatment of severe spasticity since 1984. Studies have evaluated neurological (Ashworth scale and spasm score), neurophysiological (EMG), urological (bladder function), and other clinically relevant outcomes, such as functional status activities of daily living.1-12 Little attention has been paid, however, to health related quality of life, health status measures, and costs. This study addresses health related dimensions of quality of life as well as conventional outcome measures, including muscle tone (Ashworth scale) and frequency of spasms. Treatment outcomes were evaluated during one year after pump implanta...

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The choice of a balanced allocation method for a clinical trial in otitis media with effusion

Cited by 67 publications

References 12 publications

Patients' perception of sensory disturbances of the mental nerve before and after implant surgery: a prospective study of 110 patients

Patients' perception of sensory disturbances of the mental nerve before and after implant surgery: a prospective study of 110 patients

Comparison of dynamic block randomization and minimization in randomized trials: a simulation study

Effect of intrathecal baclofen delivered by an implanted programmable pump on health related quality of life in patients with severe spasticity

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