Adaptive randomization for balancing over covariates

Covariate Balancing Methods for Randomized Controlled Trials Are Not Adversarially Robust

The first step toward investigating the effectiveness of a treatment via a randomized trial is to split the population into control and treatment groups then compare the average response of the treatment group receiving the treatment to the control group receiving the placebo. To ensure that the difference between the two groups is caused only by the treatment, it is crucial that the control and the treatment groups have similar statistics. Indeed, the validity and reliability of a trial are determined by the similarity of two groups' statistics. Covariate balancing methods increase the similarity between the distributions of the two groups' covariates. However, often in practice, there are not enough samples to accurately estimate the groups' covariate distributions. In this article, we empirically show that covariate balancing with the standardized means difference (SMD) covariate balancing measure, as well as Pocock and Simon's sequential treatment assignment method, are susceptible to worst case treatment assignments. Worst case treatment assignments are those admitted by the covariate balance measure, but result in highest possible ATE estimation errors. We developed an adversarial attack to find adversarial treatment assignment for any given trial. Then, we provide an index to measure how close the given trial is to the worst case. To this end, we provide an optimization-based algorithm, namely adversarial treatment assignment in treatment effect trials (ATASTREET), to find the adversarial treatment assignments.

Sequential covariate-adjusted randomization via hierarchically minimizing Mahalanobis distance and marginal imbalance

In comparative studies, covariate balance and sequential allocation schemes have attracted growing academic interest. Although many theoretically justified adaptive randomization methods achieve the covariate balance, they often allocate patients in pairs or groups. To better meet the practical requirements where the clinicians cannot wait for other participants to assign the current patient for some economic or ethical reasons, we propose a method that randomizes patients individually and sequentially. The proposed method conceptually separates the covariate imbalance, measured by the newly proposed modified Mahalanobis distance, and the marginal imbalance, that is the sample size difference between the 2 groups, and it minimizes them with an explicit priority order. Compared with the existing sequential randomization methods, the proposed method achieves the best possible covariate balance while maintaining the marginal balance directly, offering us more control of the randomization process. We demonstrate the superior performance of the proposed method through a wide range of simulation studies and real data analysis, and also establish theoretical guarantees for the proposed method in terms of both the convergence of the imbalance measure and the subsequent treatment effect estimation.

Optimal design for inference on the threshold of a biomarker

Enrichment designs with a continuous biomarker require the estimation of a threshold to determine the subpopulation benefitting from the treatment. This article provides the optimal allocation for inference in a two-stage enrichment design for treatment comparisons when a continuous biomarker is suspected to affect patient response. Several design criteria, associated with different trial objectives, are optimized under balanced or Neyman allocation and under equality of the first two empirical biomarker's moments. Moreover, we propose a new covariate-adaptive randomization procedure that converges to the optimum with the fastest available rate. Theoretical and simulation results show that this strategy improves the efficiency of a two-stage enrichment clinical trial, especially with smaller sample sizes and under heterogeneous responses.

Minimization in randomized clinical trials

In randomized trials, comparability of the treatment groups is ensured through allocation of treatments using a mechanism that involves some random element, thus controlling for confounding of the treatment effect. Completely random allocation ensures comparability between the treatment groups for all known and unknown prognostic factors. For a specific trial, however, imbalances in prognostic factors among the treatment groups may occur. Although accidental bias can be avoided in the presence of such imbalances by stratifying the analysis, most trialists, regulatory agencies, and other stakeholders prefer a balanced distribution of prognostic factors across the treatment groups. Some procedures attempt to achieve balance in baseline covariates, by stratifying the allocation for these covariates, or by dynamically adapting the allocation using covariate information during the trial (covariate-adaptive procedures). In this Tutorial, the performance of minimization, a popular covariate-adaptive procedure, is compared with two other commonly used procedures, completely random allocation and stratified blocked designs. Using individual patient data of 2 clinical trials (in advanced ovarian cancer and age-related macular degeneration), the procedures are compared in terms of operating characteristics (using asymptotic and randomization tests), predictability of treatment allocation, and achieved balance. Fifty actual trials of various sizes that applied minimization for treatment allocation are used to investigate the achieved balance. Implementation issues of minimization are described. Minimization procedures are useful in all trials but especially when (1) many major prognostic factors are known, (2) many centers of different sizes accrue patients, or (3) the trial sample size is moderate.

Randomised controlled trial of the effects of kefir on behaviour, sleep and the microbiome in children with ADHD: a study protocol

INTRODUCTION

Current interventions for children with attention-deficit/hyperactivity disorder (ADHD) are primarily medication, behavioural therapy and parent training. However, research suggests dietary manipulations may provide therapeutic benefit for some. There is accumulating evidence that the gut microbiome may be atypical in ADHD, and therefore, manipulating gut bacteria in such individuals may help alleviate some of the symptoms of this condition. The aim of this study is to explore the effects of supplementation with kefir (a fermented dairy drink) on ADHD symptomatology, sleep, attention and the gut microbiome in children diagnosed with ADHD.

METHODS AND ANALYSIS

A 6-week randomised, double-blind, placebo-controlled trial in 70 children aged 8-13 years diagnosed with ADHD. Participants will be recruited throughout the UK, through support groups, community groups, schools, social media and word of mouth. Children will be randomised to consume daily either dairy kefir or a placebo dairy drink for 6 weeks. The primary outcome, ADHD symptomatology, will be measured by The Strengths and Weakness of ADHD-symptoms and Normal-behaviour scale. Secondary outcomes will include gut microbiota composition (using shotgun metagenomic microbiome sequencing), gut symptomatology (The Gastrointestinal Severity Index questionnaire), sleep (using 7-day actigraphy recordings, The Child's Sleep Habits Questionnaire and Sleep Self Report questionnaire), inattention and impulsivity (with a computerised Go/NoGo test). Assessments will be conducted prior to the intervention and at the end of the intervention. Interaction between time (preintervention/postintervention) and group (probiotic/placebo) is to be analysed using a Mixed Model Analysis of Variances.

ETHICS AND DISSEMINATION

Ethical approval for the study was granted by St Mary's University Ethics Committee. Results will be disseminated through peer-reviewed publications, presentations to the scientific community and support groups.

TRIAL REGISTRATION NUMBER

NCT05155696.

Pair-switching rerandomization

Rerandomization discards assignments with covariates unbalanced in the treatment and control groups to improve estimation and inference efficiency. However, the acceptance-rejection sampling method used in rerandomization is computationally inefficient. As a result, it is time-consuming for rerandomization to draw numerous independent assignments, which are necessary for performing Fisher randomization tests and constructing randomization-based confidence intervals. To address this problem, we propose a pair-switching rerandomization (PSRR) method to draw balanced assignments efficiently. We obtain the unbiasedness and variance reduction of the difference-in-means estimator and show that the Fisher randomization tests are valid under PSRR. Moreover, we propose an exact approach to invert Fisher randomization tests to confidence intervals, which is faster than the existing methods. In addition, our method is applicable to both nonsequentially and sequentially randomized experiments. We conduct comprehensive simulation studies to compare the finite-sample performance of the proposed method with that of classical rerandomization. Simulation results indicate that PSRR leads to comparable power of Fisher randomization tests and is 3-23 times faster than classical rerandomization. Finally, we apply the PSRR method to analyze two clinical trial datasets, both of which demonstrate the advantages of our method.

Simulated annealing for balancing covariates

Covariate balance is one of the fundamental issues in designing experiments for treatment comparisons, especially in randomized clinical trials. In this article, we introduce a new class of covariate-adaptive procedures based on the Simulated Annealing algorithm aimed at balancing the allocations of two competing treatments across a set of pre-specified covariates. Due to the nature of the simulated annealing, these designs are intrinsically randomized, thus completely unpredictable, and very flexible: they can manage both quantitative and qualitative factors and be implemented in a static version as well as sequentially. The properties of the suggested proposal are described, showing a significant improvement in terms of covariate balance and inferential accuracy with respect to all the other procedures proposed in the literature. An illustrative example based on real data is also discussed.

Which training methods are effective for learning new smartphone memory apps after acquired brain injury? A pilot randomized controlled trial comparing trial and error, systematic instruction and error-based learning

This study aimed to compare the efficacy of three skills training methods (Trial and error TEL; systematic instruction SI; and error-based learning EBL) for training the use of a smartphone reminder app in individuals with an acquired brain injury. Participants (N = 38, M_age = 61.21 years, 71.1% stroke) were randomly allocated to one of three training conditions and trained over one two-hour session. Proficiency of performance with the trained app (primary outcome) was assessed immediately post-training, one- and six-weeks post-intervention. Secondary outcomes included generalization of skills, error commission, smartphone use frequency and confidence, and subjective memory complaints. Proficiency with the trained app after TEL was higher than SI immediately after the training (d = 0.87) and EBL at the one-week follow-up (d = 0.98). No differences were found six-weeks post-training. Smartphone use confidence increased at the six-week follow-up after TEL (d = 1.12) and EBL training (d = 0.91) but not after SI (d = 0.26). Self-reported memory complaints decreased across time for all groups (η_p² = 0.30). There was no clearly superior training method for optimizing proficiency with the reminder app. The expected benefits of SI and EBL may not have emerged due to the single-session format of the training. However, smartphone training via TEL or EBL has the potential to address confidence-related barriers to smartphone use.

Impact of minimal sufficient balance, minimization, and stratified permuted blocks on bias and power in the estimation of treatment effect in sequential clinical trials with a binary endpoint

Minimization is among the most common methods for controlling baseline covariate imbalance at the randomization phase of clinical trials. Previous studies have found that minimization does not preserve allocation randomness as well as other methods, such as minimal sufficient balance, making it more vulnerable to allocation predictability and selection bias. Additionally, minimization has been shown in simulation studies to inadequately control serious covariate imbalances when modest biased coin probabilities (≤0.65) are used. This current study extends the investigation of randomization methods to the analysis phase, comparing the impact of treatment allocation methods on power and bias in estimating treatment effects on a binary outcome using logistic regression. Power and bias in the estimation of treatment effect was found to be comparable across complete randomization, minimization, and minimal sufficient balance in unadjusted analyses. Further, minimal sufficient balance was found to have the most modest impact on power and the least bias in covariate-adjusted analyses. The minimal sufficient balance method is recommended for use in clinical trials as an alternative to minimization when covariate-adaptive subject randomization takes place.

Targeting Default Mode Network Dysfunction in Persons at Risk of Alzheimer's Disease with Transcranial Magnetic Stimulation (NEST4AD): Rationale and Study Design

BACKGROUND

Default mode network (DMN) dysfunction is well established in Alzheimer's disease (AD) and documented in both preclinical stages and at-risk subjects, thus representing a potential disease target. Multi-sessions of repetitive transcranial magnetic stimulation (rTMS) seem capable of modulating DMN dynamics and memory in healthy individuals and AD patients; however, the potential of this approach in at-risk subjects has yet to be tested.

OBJECTIVE

This study will test the effect of rTMS on the DMN in healthy older individuals carrying the strongest genetic risk factor for AD, the Apolipoprotein E (APOE) ɛ4 allele.

METHODS

We will recruit 64 older participants without cognitive deficits, 32 APOE ɛ4 allele carriers and 32 non-carriers as a reference group. Participants will undergo four rTMS sessions of active (high frequency) or sham DMN stimulation. Multimodal imaging exam (including structural, resting-state, and task functional MRI, and diffusion tensor imaging), TMS with concurrent electroencephalography (TMS-EEG), and cognitive assessment will be performed at baseline and after the stimulation sessions.

RESULTS

We will assess changes in DMN connectivity with resting-state functional MRI and TMS-EEG, as well as changes in memory performance in APOE ɛ4 carriers. We will also investigate the mechanisms underlying DMN modulation through the assessment of correlations with measures of neuronal activity, excitability, and structural connectivity with multimodal imaging.

CONCLUSION

The results of this study will inform on the physiological and cognitive outcomes of DMN stimulation in subjects at risk for AD and on the possible mechanisms. These results may outline the design of future non-pharmacological preventive interventions for AD.

A roadmap to using randomization in clinical trials

BACKGROUND

Randomization is the foundation of any clinical trial involving treatment comparison. It helps mitigate selection bias, promotes similarity of treatment groups with respect to important known and unknown confounders, and contributes to the validity of statistical tests. Various restricted randomization procedures with different probabilistic structures and different statistical properties are available. The goal of this paper is to present a systematic roadmap for the choice and application of a restricted randomization procedure in a clinical trial.

METHODS

We survey available restricted randomization procedures for sequential allocation of subjects in a randomized, comparative, parallel group clinical trial with equal (1:1) allocation. We explore statistical properties of these procedures, including balance/randomness tradeoff, type I error rate and power. We perform head-to-head comparisons of different procedures through simulation under various experimental scenarios, including cases when common model assumptions are violated. We also provide some real-life clinical trial examples to illustrate the thinking process for selecting a randomization procedure for implementation in practice.

RESULTS

Restricted randomization procedures targeting 1:1 allocation vary in the degree of balance/randomness they induce, and more importantly, they vary in terms of validity and efficiency of statistical inference when common model assumptions are violated (e.g. when outcomes are affected by a linear time trend; measurement error distribution is misspecified; or selection bias is introduced in the experiment). Some procedures are more robust than others. Covariate-adjusted analysis may be essential to ensure validity of the results. Special considerations are required when selecting a randomization procedure for a clinical trial with very small sample size.

CONCLUSIONS

The choice of randomization design, data analytic technique (parametric or nonparametric), and analysis strategy (randomization-based or population model-based) are all very important considerations. Randomization-based tests are robust and valid alternatives to likelihood-based tests and should be considered more frequently by clinical investigators.

Effect of a phone reminder system on patient-centered tuberculosis treatment adherence among adults in Northwest Ethiopia: a randomised controlled trial

OBJECTIVES

This study aimed to evaluate the effect of the phone reminder system on patient-centred TB treatment adherence during continuation phase, where patients are responsible for taking medication at home.

METHODS

We conducted a two-arm randomised controlled trial on adult patients with TB during the continuation phase. In the intervention arm, patients received routine care plus phone-based weekly pill refilling and daily medication reminders. In the control arm, participants received only routine care. A covariate adaptive randomisation technique was used to balance covariates during allocation. The primary outcome was adherence to patient-centred TB treatment, and secondary outcomes included provider-patient relationship and treatment outcomes. We applied per-protocol and intention-to-treat analysis techniques.

RESULTS

We randomised 306 patients to intervention (n=152) and control (n=154) groups. Adherence to patient-centred TB treatment was 79% (110/139) in intervention and 66.4% (95/143) in control groups, with relative risk (RR) (95% lower CI) (RR=1.632 (1.162 to ∞); p=0.018, one tailed). Good provider-patient relationship was 73.3% (102/139) in intervention group and 52.4% (75/143) in control group, p=0.0001. TB treatment success was 89.5% (136/152) in intervention group and 85.1% (131/154) in control group, p=0.1238.

CONCLUSIONS

Mobile phone-based weekly refilling with daily medication reminder system improved adherence to patient-centred TB treatment and provider-patient relationship; however, there was no significant effect on treatment success.

TRIAL REGISTRATION NUMBER

Pan African Clinical Trials Registry (PACTR201901552202539).

Testing for treatment effect in covariate-adaptive randomized trials with generalized linear models and omitted covariates

Concerns have been expressed over the validity of statistical inference under covariate-adaptive randomization despite the extensive use in clinical trials. In the literature, the inferential properties under covariate-adaptive randomization have been mainly studied for continuous responses; in particular, it is well known that the usual two-sample t-test for treatment effect is typically conservative. This phenomenon of invalid tests has also been found for generalized linear models without adjusting for the covariates and are sometimes more worrisome due to inflated Type I error. The purpose of this study is to examine the unadjusted test for treatment effect under generalized linear models and covariate-adaptive randomization. For a large class of covariate-adaptive randomization methods, we obtain the asymptotic distribution of the test statistic under the null hypothesis and derive the conditions under which the test is conservative, valid, or anti-conservative. Several commonly used generalized linear models, such as logistic regression and Poisson regression, are discussed in detail. An adjustment method is also proposed to achieve a valid size based on the asymptotic results. Numerical studies confirm the theoretical findings and demonstrate the effectiveness of the proposed adjustment method.

A comparison of systematic instruction, error-based learning and trial and error to train the use of smartphone memory apps after acquired brain injury: A three-armed phase II randomised controlled trial study protocol

Background:

The uptake of smartphones as external compensatory memory aids following an acquired brain injury (ABI) in rehabilitation settings is low. Potential reasons for this include professionals not having evidence-based guidelines regarding the best methods to train smartphone use and prospective users not being familiar with technology and/or having memory and learning difficulties. This paper describes the protocol of a study that aims to compare the efficacy of three training methods (Systematic Instruction, Error-based Learning and Trial-and-Error) for training the use of a smartphone reminder app, in people with ABI presenting with memory complaints.

Methods/Design:

This is a three-armed, assessor-blinded, Phase II randomised controlled trial. The estimated sample size is 51 participants aged >18 years, who are equally randomised to one of the three training groups. They are seen across four sessions: one to conduct baseline measures; one for training the use of an app and two for follow-up assessments (1- and 6-weeks post-training). The main outcome measure is proficiency of performance in tasks with the trained app. Secondary outcomes include generalisation of skills to other apps, number of errors committed while attempting the tasks, frequency of smartphone usage in general and as a memory aid and confidence in smartphone use and memory self-efficacy. Outcome measures are collected by an independent blinded assessor. Proficiency of performance, generalisation of skills and error commission are measured immediately post-training and at the two follow-up sessions. The other secondary measures are taken pre-intervention and at the two follow-up sessions.

Discussion:

This study will provide initial evidence regarding the efficacy of three different methods to train ABI survivors with memory difficulties in how to use smartphone apps as compensatory memory aids. The results could inform a larger Phase III trial and advance knowledge concerning the advantages or disadvantages of using error-reducing and trial-and-error techniques. Further, the findings could determine the potential of error-based learning as an emerging training method for people with memory impairment within rehabilitation.

The impact of misclassification on covariate-adaptive randomized clinical trials

Covariate-adaptive randomization (CAR) is widely used in clinical trials to balance treatment allocation over covariates. Over the past decade, significant progress has been made on the theoretical properties of covariate-adaptive design and associated inference. However, most results are established under the assumption that the covariates are correctly measured. In practice, measurement error is inevitable, resulting in misclassification for discrete covariates. When covariate misclassification is present in a clinical trial conducted using CAR, the impact is twofold: it impairs the intended covariate balance, and raises concerns over the validity of test procedures. In this paper, we consider the impact of misclassification on covariate-adaptive randomized trials from the perspectives of both design and inference. We derive the asymptotic normality, and thereby the convergence rate, of the imbalance of the true covariates for a general family of covariate-adaptive randomization methods, and show that a superior covariate balance can still be attained compared to complete randomization. We also show that the two sample t-test is conservative, with a reduced Type I error, but that this can be corrected using a bootstrap method. Moreover, if the misclassified covariates are adjusted in the model used for analysis, the test maintains its nominal Type I error, with an increased power. Our results support the use of covariate-adaptive randomization in clinical trials, even when the covariates are subject to misclassification.

Statistical properties of minimal sufficient balance and minimization as methods for controlling baseline covariate imbalance at the design stage of sequential clinical trials

When the number of baseline covariates whose imbalance needs to be controlled in a sequential randomized controlled trial is large, minimization is the most commonly used method for randomizing treatment assignments. The lack of allocation randomness associated with the minimization method has been the source of controversy, and the need to reduce even minor imbalances inherent in the minimization method has been challenged. The minimal sufficient balance (MSB) method is an alternative to the minimization method. It prevents serious imbalance from a large number of covariates while maintaining a high level of allocation randomness. In this study, the two treatment allocation methods are compared with regards to the effectiveness of balancing covariates across treatment arms and allocation randomness in equal allocation clinical trials. The MSB method proves to be equal or superior in both respects. In addition, type I error rate is preserved in analyses for both balancing methods, when using a binary endpoint.

Combined effect of pill refilling and self-medication reminder system on patients' adherence to tuberculosis treatment during continuation phase in Northwest Ethiopia: a study protocol for randomised controlled trial

Introduction

Patients’ failure to adhere on tuberculosis (TB) treatment leads to drug resistance, relapse and death. Non-adherence to TB treatment is higher during continuation treatment phase. The study aimed to evaluate effectiveness of combined pill refilling and medication reminders on adherence to TB treatment.

Methods and analysis

A two-arm randomised controlled trial on adult patients with TB was used during continuation treatment phase. In the first arm, in addition to usual care, participants will receive cellphone-based daily medication and weekly pill refilling reminders. In the control arm, participants will receive only usual care. The study will use a covariate adaptive randomisation technique to balance covariates during allocation. The primary outcome is patients’ adherence to TB treatment and secondary outcomes are attendance to clinic and treatment outcomes. We apply intention to treat with generalised linear mixed model.

Ethics and dissemination

Ethical approval was obtained from Institutional Review Board of University of Gondar. Written informed consent was applied during enrolment. We will publish findings in peer-reviewed, scientific journals and conferences.

Trial registration number

PACTR201901552202539.

Mood outcomes of a behavioral treatment for urinary incontinence in prostate cancer survivors

PURPOSE

This study aimed to assess whether prostate cancer survivors who received a behavioral intervention to urinary incontinence had experienced a significant mood improvement.

METHODS

One hundred fifty-three prostate cancer survivors with persistent incontinence were included in this secondary data analysis. They were randomly assigned to usual care or interventions that provided pelvic floor muscle exercises and self-management skills. All subjects had measures of anxiety, depression, and anger at baseline, 3 months (post-intervention), and 6 months (follow-up). Negative binomial regression analysis was performed to examine the group status, daily leakage frequency at 3 months, and their interactions at 3 months as predictors for mood outcomes at 6 months, controlling for demographic and medical variables.

RESULTS

The main effect of daily leakage frequency at 3 months significantly predicted anxiety at 6 months (p < .01). The group main effect on any mood outcomes at 6 months was not statistically significant. The interaction between the group and 3-month leakage had a significant effect on anxiety; intervention subjects achieving a significant leakage reduction at 3 months exhibited significantly less anxiety at 6 months than other subjects (p = .04). Age, employment status, and receiving surgery at baseline were significantly associated with less anxiety, depression, and anger at 6 months.

CONCLUSIONS

Reduced urinary incontinence significantly predicted less anxiety, especially among the intervention subjects. The findings suggest a significant association between a behavioral therapy of urinary incontinence and anxiety reduction in prostate cancer survivors.

MASked-unconTrolled hypERtension management based on office BP or on ambulatory blood pressure measurement (MASTER) Study: a randomised controlled trial protocol

INTRODUCTION

Masked uncontrolled hypertension (MUCH) carries an increased risk of cardiovascular (CV) complications and can be identified through combined use of office (O) and ambulatory (A) blood pressure (BP) monitoring (M) in treated patients. However, it is still debated whether the information carried by ABPM should be considered for MUCH management. Aim of the MASked-unconTrolled hypERtension management based on OBP or on ambulatory blood pressure measurement (MASTER) Study is to assess the impact on outcome of MUCH management based on OBPM or ABPM.

METHODS AND ANALYSIS

MASTER is a 4-year prospective, randomised, open-label, blinded-endpoint investigation. A total of 1240 treated hypertensive patients from about 40 secondary care clinical centres worldwide will be included -upon confirming presence of MUCH (repeated on treatment OBP <140/90 mm Hg, and at least one of the following: daytime ABP ≥135/85 mm Hg; night-time ABP ≥120/70 mm Hg; 24 hour ABP ≥130/80 mm Hg), and will be randomised to a management strategy based on OBPM (group 1) or on ABPM (group 2). Patients in group 1 will have OBP measured at 0, 3, 6, 12, 18, 24, 30, 36, 42 and 48 months and taken as a guide for treatment; ABPM will be performed at randomisation and at 12, 24, 36 and 48 months but will not be used to take treatment decisions. Patients randomised to group 2 will have ABPM performed at randomisation and all scheduled visits as a guide to antihypertensive treatment. The effects of MUCH management strategy based on ABPM or on OBPM on CV and renal intermediate outcomes (changing left ventricular mass and microalbuminuria, coprimary outcomes) at 1 year and on CV events at 4 years and on changes in BP-related variables will be assessed.

ETHICS AND DISSEMINATION

MASTER study protocol has received approval by the ethical review board of Istituto Auxologico Italiano. The procedures set out in this protocol are in accordance with principles of Declaration of Helsinki and Good Clinical Practice guidelines. Results will be published in accordance with the CONSORT statement in a peer-reviewed scientific journal.

TRIAL REGISTRATION NUMBER

NCT02804074; Pre-results.

Safety and Efficacy of Losartan 50 mg in Reducing Blood Pressure among Patients with Post-Dialysis Euvolemic Hypertension: A Randomized Control Trial

The aim of current study was to assess the effectiveness of losartan 50 mg in reducing blood pressure among post-dialysis euvolemic hypertensive patients, observing their survival trends and adverse events during the course of study. A multicentre, prospective, randomised, single-blind trial was conducted to assess the effect of losartan 50 mg every other day (EOD), once a morning (OM) among post-dialysis euvolemic hypertensive patients. Post-dialysis euvolemic assessment was done by a body composition monitor (BCM). Covariate Adaptive Randomization was used for allocation of participants to the standard or intervention arm. Of the total 229 patients, 96 (41.9%) were identified as post-dialysis euvolemic hypertensive. Final samples of 88 (40.1%) patients were randomized into standard and intervention arms. After follow-up of 12 months’ pre-dialysis systolic (p < 0.001) and diastolic (p 0.01), intradialysis diastolic (p 0.02), post-dialysis systolic (p < 0.001) and diastolic (p < 0.001) blood pressure was reduced from the baseline among intervention-arm patients Compared to only pre-dialysis systolic blood pressure (p 0.003) among standard arm patients after 12 months of follow. Total of six deaths were reported among standard-arm patients compared to 2 deaths among the intervention arm. Losartan 50 mg achieve an overall significant decline in blood pressure among post-dialysis euvolemic hypertensive patients.

Minimal sufficient balance randomization for sequential randomized controlled trial designs: results from the ESCAPE trial

Background

We describe the implementation of minimal sufficient balance randomization, a covariate-adaptive randomization technique, used for the “Endovascular treatment for Small Core and Anterior circulation Proximal occlusion with Emphasis on minimizing CT to recanalization times” (ESCAPE) trial.

Methods

The ESCAPE trial is a prospective, multicenter, randomized clinical trial that enrolled subjects with the following main inclusion criteria: less than 12 h from symptom onset, age 18 years or older, baseline NIHSS score > 5, ASPECTS score > 5 and computed tomography angiography (CTA) evidence of carotid T/L or M1-segment middle cerebral artery (MCA) occlusion, and at least moderate collaterals by CTA. Patients were randomized using a real-time, dynamic, Internet-based, minimal sufficient balance randomization method that balanced the study arms with respect to baseline covariates including age, sex, baseline NIHSS score, site of arterial occlusion, baseline ASPECTS score and treatment with intravenously administered alteplase.

Results

Permutation-based tests of group differences confirmed group balance across several baseline covariates including sex (p = 1.00), baseline NIHSS score (p = 0.95), site of arterial occlusion (p = 1.00), baseline ASPECTS score (p = 0.28), treatment with intravenously administered alteplase (p = 0.31), and age (p = 0.67).

Conclusion

Results from the ESCAPE trial demonstrate the feasibility and the benefit of this covariate adaptive randomization scheme in small-sample trials and for data monitoring endeavors.

Trial registration

ESCAPE trial – NCT01778335 – at www.clinicaltrials.gov. Registered on 29 January 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2264-1) contains supplementary material, which is available to authorized users.

Efficacy of Losartan in the management of Post-Dialysis Euvolemic Hypertension (HELD-Trial): A Single-Blind Randomized Control Trial

To assess the effectiveness of losartan 50 mg on post dialysis euvolemic hypertensive patients against standard antihypertensive pharmacotherapy. A multicentre, prospective, randomized, single-blind trial was conducted to assess the effect of losartan 50 mg every other day (EOD), once a morning (OM) among post-dialysis euvolemic hypertensive patients. Covariate-adaptive randomization was used to allocate participants to a standard or treatment arm, and they were followed up for eight weeks. Pre-, intra- and post-dialysis session blood pressure (BP) measurements were recorded along with any adverse events. A total of 88 patients were randomized into standard (n = 44) and treatment arms (n = 44) and were followed for a period of 8 weeks. In the standard group, the mean post-dialysis blood pressure dropped by 0.3 mmHg by the end of the 8^th week. However the treatment arm reported a drop of 2.4 mmHg of BP drop during the 8-week trial period. Analysis suggests that there was a significant difference in blood pressure readings at the end of 8 weeks among patients treated with losartan (P < 0.001). However, no such statistical association was observed in the standard arm (P 0.75). A slow, steady significant decline in post-dialysis BP was observed among euvolemic hypertensive patients that were treated with losartan 50 mg.

Generalized Efron's biased coin design and its theoretical properties

In clinical trials with two treatment arms, Efron's biased coin design, Efron (1971), sequentially assigns a patient to the underrepresented arm with probability p > ½. Under this design the proportion of patients in any arm converges to ½, and the convergence rate is n-1, as opposed to n-½ under some other popular designs. The generalization of Efron's design to K ≥ 2 arms and an unequal target allocation ratio (q1, . . ., qK) can be found in some papers, most of which determine the allocation probabilities ps in a heuristic way. Nonetheless, it has been noted that by using inappropriate ps, the proportion of patients in the K arms never converges to the target ratio. We develop a general theory to answer the question of what allocation probabilities ensure that the realized proportions under a generalized design still converge to the target ratio (q1, . . ., qK) with rate n-1.

Mild cognitive impairment in Parkinson's disease is improved by transcranial direct current stimulation combined with physical therapy

BACKGROUND

Parkinson's disease (PD) is characterized by both motor and cognitive deficits. In PD, physical exercise has been found to improve physical functioning. Recent studies demonstrated that repeated sessions of transcranial direct current stimulation led to an increased performance in cognitive and motor tasks in patients with PD.

OBJECTIVES

The present study investigated the effects of anodal transcranial direct current stimulation applied over the dorsolateral prefrontal cortex and combined with physical therapy in PD patients.

METHODS

A total of 20 patients with PD were assigned to 1 of 2 study groups: group 1, anodal transcranial direct current stimulation plus physical therapy (n = 10) or group 2, placebo transcranial direct current stimulation plus physical therapy (n = 10). The 2 weeks of treatment consisted of daily direct current stimulation application for 25 minutes during physical therapy. Long-term effects of treatment were evaluated on clinical, neuropsychological, and motor task performance at 3-month follow-up.

RESULTS

An improvement in motor abilities and a reduction of depressive symptoms were observed in both groups after the end of treatment and at 3-month follow-up. The Parkinson's Disease Cognitive Rating Scale and verbal fluency test performances increased only in the anodal direct current stimulation group with a stable effect at follow-up.

CONCLUSIONS

The application of anodal transcranial direct current stimulation may be a relevant tool to improve cognitive abilities in PD and might be a novel therapeutic strategy for PD patients with mild cognitive impairment. © 2016 International Parkinson and Movement Disorder Society.

Effects of Patient Centered Interventions on Persistent Urinary Incontinence after Prostate Cancer Treatment: A Randomized, Controlled Trial

PURPOSE

We examined whether an intervention combining pelvic floor muscle exercise and symptom self-management would improve urinary continence and quality of life in patients with prostate cancer.

MATERIALS AND METHODS

In a randomized, controlled, longitudinal clinical trial 279 patients with prostate cancer with persistent urinary incontinence were randomized to 1 of 3 groups, including biofeedback pelvic floor muscle exercise plus a support group, the biofeedback exercise plus telephone contact and usual care without intervention. The biofeedback plus support and plus telephone groups received 1 session of biofeedback assisted exercise and 6 biweekly sessions of problem solving therapy. This delivered symptom management skills through a peer support group or telephone contacts for 3 months. All subjects were assessed in blinded fashion at baseline, and 3 and 6 months for urinary leakage frequency, leakage amount and disease specific quality of life.

RESULTS

A total of 244 subjects completed the study. The biofeedback plus support and biofeedback plus telephone groups had a lower frequency of daily urinary leakage than the group with usual care without intervention at 3 months (p=0.019 and p≤0.001, respectively) but not at 6 months. The biofeedback plus support group but not the biofeedback plus telephone group had 13.3 gm lower leakage at 6 months than the usual care group (p=0.003). Overall the biofeedback plus support and plus telephone groups reported less symptom severity (p≤0.001) and fewer incontinence problems (p≤0.01) than the usual care group at 6 months.

CONCLUSIONS

Study findings show that pelvic floor muscle exercise practice plus symptom self-management in a peer support setting can significantly improve urinary continence and quality of life in patients with prostate cancer.