Adaptive Randomized Clinical Trials Research Articles

GABA Analogue HSK16149 in Chinese Patients With Diabetic Peripheral Neuropathic Pain

Many patients with diabetic peripheral neuropathic pain (DPNP) experience inadequate relief, despite best available medical treatments. There are no approved and effective therapies for patients with DPNP in China. To evaluate the efficacy and safety of capsules containing γ-aminobutyric acid (GABA) analogue HSK16149 in the treatment of Chinese patients with DPNP. This phase 2 to 3 adaptive randomized clinical trial was multicenter, double blind, and placebo and pregabalin controlled. The trial started on December 10, 2020, and concluded on July 8, 2022. In stage 1, various doses of HSK16149 were evaluated to determine safety and efficacy for stage 2. The second stage then validated the efficacy and safety of the recommended dose. In stage 1, enrolled patients (n = 363) were randomized 1:1:1:1:1:1 to 4 HSK16149 doses (40, 80, 120, or 160 mg/d), pregabalin (300 mg/d), or placebo. In stage 2, patients (n = 362) were randomized 1:1:1 to receive HSK16149, 40 or 80 mg/d, or placebo. The final efficacy and safety analysis pooled data from patients receiving the same treatment. The primary efficacy end point in stage 1 was the change from baseline in average daily pain score (ADPS) at week 5. The primary efficacy end point in stage 2 was the change from baseline in ADPS at week 13. When the final statistical analysis was performed, the P values calculated from the independent data of each phase were combined using the weighted inverse normal method to make statistical inferences. Of 725 randomized patients in the full-analysis set (393 men [54.2%]; mean [SD] age, 58.80 [9.53] years; 700 [96.6%] of Han Chinese ethnicity), 177 received placebo; 178, HSK16149, 40 mg/d; 179, HSK16149, 80 mg/d; 66, HSK16149, 120 mg/d; 63, HSK16149, 160 mg/d; and 62, pregabalin, 300 mg/d. A total of 644 patients (88.8%) completed the study. The 40- and 80-mg/d doses of HSK16149 were recommended in stage 2. At week 13, the ADPS mean (SD) change from baseline was -2.24 (1.55) for the 40-mg/d and -2.16 (1.79) for 80-mg/d groups and -1.23 (1.68) for the placebo group, showing statistical significance for both HSK16149 doses vs placebo (both P < .001). In a safety set (n = 726), 545 patients (75.1%) had adverse events, which were generally mild to moderate, with dizziness and somnolence being the most common. Forty- and eighty-mg/d doses of HSK16149 were recommended for treating patients with DPNP in China. The efficacy of HSK16149 capsules was superior to placebo in all groups for relieving DPNP and appeared well tolerated. ClinicalTrials.gov Identifier: NCT04647773.

Two-stage randomized clinical trials with a right-censored endpoint: Comparison of frequentist and Bayesian adaptive designs.

Adaptive randomized clinical trials are of major interest when dealing with a time-to-event outcome in a prolonged observation window. No consensus exists either to define stopping boundaries or to combine values or test statistics in the terminal analysis in the case of a frequentist design and sample size adaptation. In a one-sided setting, we compared three frequentist approaches using stopping boundaries relying on -spending functions and a Bayesian monitoring setting with boundaries based on the posterior distribution of the log-hazard ratio. All designs comprised a single interim analysis with an efficacy stopping rule and the possibility of sample size adaptation at this interim step. Three frequentist approaches were defined based on the terminal analysis: combination of stagewise statistics (Wassmer) or of values (Desseaux), or on patientwise splitting (Jörgens), and we compared the results with those of the Bayesian monitoring approach (Freedman). These different approaches were evaluated in a simulation study and then illustrated on a real dataset from a randomized clinical trial conducted in elderly patients with chronic lymphocytic leukemia. All approaches controlled for the type I error rate, except for the Bayesian monitoring approach, and yielded satisfactory power. It appears that the frequentist approaches are the best in underpowered trials. The power of all the approaches was affected by the violation of the proportional hazards (PH) assumption. For adaptive designs with a survival endpoint and a one-sided alternative hypothesis, the Wassmer and Jörgens approaches after sample size adaptation should be preferred, unless violation of PH is suspected.

An Adaptive Pragmatic Randomized Controlled Trial of Emergency Department Acupuncture for Acute Musculoskeletal Pain Management

Acute musculoskeletal pain in emergency department (ED) patients is frequently severe and challenging to treat with medications alone. The purpose of this study was to determine the feasibility, acceptability, and effectiveness of adding ED acupuncture to treat acute episodes of musculoskeletal pain in the neck, back, and extremities. In this pragmatic 2-stage adaptive open-label randomized clinical trial, Stage 1 identified whether auricular acupuncture (AA; based on the battlefield acupuncture protocol) or peripheral acupuncture (PA; needles in head, neck, and extremities only), when added to usual care was more feasible, acceptable, and efficacious in the ED. Stage 2 assessed effectiveness of the selected acupuncture intervention(s) on pain reduction compared to usual care only (UC). Licensed acupuncturists delivered AA and PA. They saw and evaluated but did not deliver acupuncture to the UC group as an attention control. All participants received UC from blinded ED providers. Primary outcome was 1-hour change in 11-point pain numeric rating scale. Stage 1 interim analysis found both acupuncture styles similar, so Stage 2 continued all 3 treatment arms. Among 236 participants randomized, demographics and baseline pain were comparable across groups. When compared to UC alone, reduction in pain was 1.6 (95% confidence interval [CI]: 0.7 to 2.6) points greater for AA+UC and 1.2 (95% CI: 0.3 to 2.1) points greater for PA+UC patients. Participants in both treatment arms reported high satisfaction with acupuncture. ED acupuncture is feasible and acceptable and can reduce acute musculoskeletal pain better than UC alone.

Facilities for optimizing and designing multiarm multistage (MAMS) randomized controlled trials with binary outcomes

We introduce two commands, nstagebin and nstagebinopt, that can be used to facilitate the design of multiarm multistage (MAMS) trials with binary outcomes. MAMS designs are a class of efficient and adaptive randomized clinical trials that have successfully been used in many disease areas, including cancer, tuberculosis, maternal health, COVID-19, and surgery. The nstagebinopt command finds a class of efficient “admissible” designs based on an optimality criterion using a systematic search procedure. The nstagebin command calculates the stagewise sample sizes, trial timelines, and overall operating characteristics of MAMS designs with binary outcomes. Both commands allow the use of Dunnett’s correction to account for multiple testing. We also use the ROSSINI 2 MAMS design, an ongoing MAMS trial in surgical wound infection, to illustrate the capabilities of both commands. The new commands facilitate the design of MAMS trials with binary outcomes where more than one research question can be addressed under one protocol.

Changing Trends in the Global Consumption of Treatments Used in Hospitalized Patients for COVID-19: A Time Series Multicentre Study.

To analyze trends in the prescription of COVID-19 treatments for hospitalized patients during the pandemic. Multicenter, ecological, time-series study of aggregate data for all adult patients with COVID-19 treated in five acute-care hospitals in Barcelona, Spain, between March 2020 and May 2021. Trends in the monthly prevalence of drugs used against COVID-19 were analyzed by the Mantel-Haenszel test. The participating hospitals admitted 22,277 patients with COVID-19 during the study period, reporting an overall mortality of 10.8%. In the first months of the pandemic, lopinavir/ritonavir and hydroxychloroquine were the most frequently used antivirals, but these fell into disuse and were replaced by remdesivir in July 2020. By contrast, the trend in tocilizumab use varied, first peaking in April and May 2020, declining until January 2021, and showing a discrete upward trend thereafter. Regarding corticosteroid use, we observed a notable upward trend in the use of dexamethasone 6 mg per day from July 2020. Finally, there was a high prevalence of antibiotics use, especially azithromycin, in the first three months, but this decreased thereafter. Treatment for patients hospitalized with COVID-19 evolved with the changing scientific evidence during the pandemic. Initially, multiple drugs were empirically used that subsequently could not demonstrate clinical benefit. In future pandemics, stakeholders should strive to promote the early implementation of adaptive randomized clinical trials.

Design of an adaptive randomized clinical trial of intravenous citrulline for sickle cell pain crisis in the emergency department

BackgroundVaso-occlusive pain crisis (VOC) is the most frequent cause for Emergency Department (ED) visits and hospital admissions for patients with sickle cell disease (SCD). Nitric oxide plays a critical role in the pathogenesis of vaso-occlusion. The amino acid, citrulline, is the main endothelial nitric oxide booster that offers the potential to ameliorate vaso-occlusion and decrease the risk of hospitalization. ObjectiveIn this two-part study, the goal of the first part is to determine the pharmacokinetic profile of intravenous (IV) l-citrulline and optimal dose for the second part of the study, which is to determine the efficacy and tolerability of the intervention in patients with SCD. DesignA phase I/IIA open-label dose-finding study with subsequent double-blind, placebo-controlled, randomized Study of l-citrulline in children and adolescents with SCD presenting to the ED in VOC. MethodsPart 1: Subjects experiencing VOC are enrolled in an open-label, ascending dose of IV l-citrulline to identify the optimum dose with endpoints of pharmacokinetic parameters, pain scores, reduction of opioid use, quality of life, proportion admitted to the hospital for treatment of pain, readmission rates, and assessment of adverse events. Part 2 of the trial is a double-blind, placebo-controlled adaptive “pick-the-winner” design to evaluate the efficacy and tolerability of IV l-citrulline in patients with SCD while receiving standard of care therapy for VOC. SummaryThis ED based sickle cell adaptive trial will determine the optimal dose for IV citrulline and whether the intervention improves outcome as a potential novel therapy for VOC in SCD.

Estimation of hurst exponent for sequential monitoring of clinical trials with covariate adaptive randomization

BackgroundClassical Brownian motion (BM) has been commonly used in monitoring clinical trials including those with covariate adaptive randomization (CAR). Independent increment property is commonly assumed in the sequential monitoring process of the clinical trials with CAR designs. However, in reality, correlation may exist in the error terms of the underlying model, resulting in dependent increment in the sequential monitoring process. MethodsWe conducted simulations for estimating the Hurst exponent to evaluate the stochastic property in the covariate adaptive randomized clinical trials under two scenarios: 1. CAR designs with independent and identically distributed error terms. 2. CAR designs with correlated error terms. The theoretical properties of covariate adaptive randomized clinical trials with correlated error structure were investigated. A test statistic including the covariance pattern of the error terms was proposed. ConclusionIn our study, the sequential test statistics under CAR procedure is shown to be asymptotically Brownian motion when the error structure is correctly specified. Further, Brownian motion is a special case of fractional Brownian motion when Hurst exponent equals to 0.5. Our simulations are consistent with the theoretical asymptotic results.

Effect of P2Y12 Inhibitors on Survival Free of Organ Support Among Non–Critically Ill Hospitalized Patients With COVID-19

Platelets represent a potential therapeutic target for improved clinical outcomes in patients with COVID-19. To evaluate the benefits and risks of adding a P2Y12 inhibitor to anticoagulant therapy among non-critically ill patients hospitalized for COVID-19. An open-label, bayesian, adaptive randomized clinical trial including 562 non-critically ill patients hospitalized for COVID-19 was conducted between February 2021 and June 2021 at 60 hospitals in Brazil, Italy, Spain, and the US. The date of final 90-day follow-up was September 15, 2021. Patients were randomized to a therapeutic dose of heparin plus a P2Y12 inhibitor (n = 293) or a therapeutic dose of heparin only (usual care) (n = 269) in a 1:1 ratio for 14 days or until hospital discharge, whichever was sooner. Ticagrelor was the preferred P2Y12 inhibitor. The composite primary outcome was organ support-free days evaluated on an ordinal scale that combined in-hospital death (assigned a value of -1) and, for those who survived to hospital discharge, the number of days free of respiratory or cardiovascular organ support up to day 21 of the index hospitalization (range, -1 to 21 days; higher scores indicate less organ support and better outcomes). The primary safety outcome was major bleeding by 28 days as defined by the International Society on Thrombosis and Hemostasis. Enrollment of non-critically ill patients was discontinued when the prespecified criterion for futility was met. All 562 patients who were randomized (mean age, 52.7 [SD, 13.5] years; 41.5% women) completed the trial and 87% received a therapeutic dose of heparin by the end of study day 1. In the P2Y12 inhibitor group, ticagrelor was used in 63% of patients and clopidogrel in 37%. The median number of organ support-free days was 21 days (IQR, 20-21 days) among patients in the P2Y12 inhibitor group and was 21 days (IQR, 21-21 days) in the usual care group (adjusted odds ratio, 0.83 [95% credible interval, 0.55-1.25]; posterior probability of futility [defined as an odds ratio <1.2], 96%). Major bleeding occurred in 6 patients (2.0%) in the P2Y12 inhibitor group and in 2 patients (0.7%) in the usual care group (adjusted odds ratio, 3.31 [95% CI, 0.64-17.2]; P = .15). Among non-critically ill patients hospitalized for COVID-19, the use of a P2Y12 inhibitor in addition to a therapeutic dose of heparin, compared with a therapeutic dose of heparin only, did not result in an increased odds of improvement in organ support-free days within 21 days during hospitalization. ClinicalTrials.gov Identifier: NCT04505774.

Ethical dimensions in randomized trials and off-label use of investigational drugs for COVID-19 treatment

Coronavirus disease 2019 (COVID-19) is a fast-developing viral pandemic spreading across the globe. Due to lack of availability of proven medicines against COVID-19, physicians have resorted to treatments through large trials of investigational drugs with poor evidence or those used for similar diseases. Large trials randomize 100–500+ patients at multiple hospitals in different countries to either receive these drugs or standard treatment. In order to expedite the process, some regulatory agencies had also given permission to use drugs approved for other diseases, despite a lack of evidence of efficacy in COVID-19. In this review, we highlight the potential ethical issues that should be addressed during the use of investigational drugs with little prior evidence as a treatment options during a pandemic. We discuss the impact of design of randomized clinical trials using LOTUS trial as an example and that of off-label use of drugs like chloroquine/hydroxychloroquine (CQ/HQ) on the safety of patients during COVID-19. We conclude that the adaptive randomized clinical trial designs offer a flexible and efficient approach, enabling patients to quickly switch to successful treatments, while minimizing the number of patients on standard of care. Randomized clinical trial design should consider blinding of investigators and only representative patients who can provide consent should be included. We also conclude the emergency approvals of drugs should be carefully issued and off-label use should be restricted in pandemics. Streamlined regulatory guidelines for emergency drug use in a pandemic can also help in providing benefit and minimizing harm to patients in the future.

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

A cost/benefit analysis of clinical trial designs for COVID-19 vaccine candidates.

We compare and contrast the expected duration and number of infections and deaths averted among several designs for clinical trials of COVID-19 vaccine candidates, including traditional and adaptive randomized clinical trials and human challenge trials. Using epidemiological models calibrated to the current pandemic, we simulate the time course of each clinical trial design for 756 unique combinations of parameters, allowing us to determine which trial design is most effective for a given scenario. A human challenge trial provides maximal net benefits-averting an additional 1.1M infections and 8,000 deaths in the U.S. compared to the next best clinical trial design-if its set-up time is short or the pandemic spreads slowly. In most of the other cases, an adaptive trial provides greater net benefits.

Modern Adaptive Randomized Clinical Trials: Statistical and Practical Aspects

Modern Adaptive Randomized Clinical Trials: Statistical and Practical Aspects

An adaptive randomized clinical trial in interstitial cystitis/bladder pain syndrome evaluating efficacy of ASP3652 and the relationship between disease characteristics and Hunner's lesions.

The primary purpose of this study was to evaluate the effect of the fatty acid amide hydrolase (FAAH) inhibitor ASP3652 on efficacy and safety in patients with Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS). The secondary purpose was to evaluate phenotyping based on Hunner's lesions (HL). In this randomized trial, adult female patients with moderate/severe IC/BPS received 12weeks of treatment with an oral dose of ASP3652 (50, 150, or 300mg twice daily) or placebo. A Bayesian model was employed using accumulating data to adjust the randomization probability and to analyze the primary efficacy variable (change from baseline to end of treatment in Mean Daily Pain [MDP; range 0-10]). Study outcomes and patient characteristics of patients with and without HL (HL+ and HL-) were compared. In total, 287 patients were randomized. The 300mg dose group (n = 97) showed the largest effect, i.e., a mean change from baseline to end of treatment of -1.73 in MDP. However, the mean difference from placebo was 0.02. The probability that this dose was better than placebo was 13.5%. Adverse event incidence was low and similar between study groups. HL+ patients were older and had more severe symptoms than HL-. An association was suggested in HL+ patients between changes in micturition frequency and MDP (R = 0.41 [95% CI 0.18, 0.63]), which was not observed in HL- (R = 0.04 [95% CI -0.16, 0.29]). ASP3652 was safe and well tolerated, but did not show efficacy in IC/BPS. The observed differences between HL+ and HL- suggest that IC/BPS diagnosis and treatment may be approached differently in these two phenotypes. EudraCT number 2011-004555-39, date of registration: 2012-05-07.

EarLy Elimination of Fatty Acids iN hypertriglyceridemia-induced acuTe pancreatitis (ELEFANT trial): Protocol of an open-label, multicenter, adaptive randomized clinical trial

IntroductionAcute pancreatitis (AP) is a life-threatening inflammatory disease, with no specific pharmacological treatment. However, concerning some etiologies, early specific intervention (such as ERCP in biliary AP) has proven to be remarkably beneficial. Hypertriglyceridemia (HTG) induces severe pancreatic damage by several direct (cellular damage) and indirect (deterioration of microcirculation) mechanisms. Published data suggest that early removal of triglycerides (TGs) and toxic free fatty acids (FFAs) may be advantageous; however, high-quality evidence is still missing in the literature. MethodsDesign: ELEFANT is a randomized controlled, multicenter, international trial testing the concept that early elimination of TGs and FFAs from the blood is beneficial in HTG-AP. The study will be performed with the adaptive “drop-the-loser” design, which supports the possibility of dropping the inferior treatment arm, based on the results of the interim analysis. Patients with HTG-AP defined by TG level over 11.3 mmol/l (1000 mg/dL) are randomized into three groups: (A) patients who undergo plasmapheresis and receive aggressive fluid resuscitation; (B) patients who receive insulin and heparin treatment with aggressive fluid resuscitation; and (C) patients with aggressive fluid resuscitation. Please note that all intervention must be started within 48 h from the onset of abdominal pain. Exclusion criteria are designed logically to decrease the possibility of any distorting effects of other diseases. The composite primary endpoint will include both severity and mortality. ResultsOur null hypothesis is that early elimination of HTG and FFAs reduces the risk of mortality and severity of AP. Sample size calculation suggests that 495 patients will need to be enrolled in order to confirm or reject the hypothesis with a 10% dropout, 80% power and 95% significance level. The general safety and quality checks required for high-quality evidence will be adhered to. The study will be organized between February 2020 and December 2025. ConclusionOur study would provide the first direct evidence for or against early intervention in HTG-induced AP.

Sequential monitoring of covariate adaptive randomized clinical trials with sample size re-estimation

Once scientific questions are determined, other design features of clinical trials including increasing the power while controlling the type I error rate, planning interim analysis, and achieving treatment balance among subgroups will be either required or preferred. We propose to sequentially monitor the covariate adaptive randomization (CAR) procedures with sample size re-estimation (SSR) to satisfy a variety of design objectives of clinical trials. However, each of the three adaptive designs (sequential monitoring, CAR, and SSR) poses a challenge to the control of the type I error rate. In this paper, we investigated how to utilize the advantages of the three adaptive methods and control the type I error rate. We proved that the asymptotic joint distribution of the sequential statistics follows the asymptotic canonical joint distribution defined in Jennison and Turnbull [14]. Besides, numerical studies demonstrated that our methods could control the type I error rate, increase the power, and lead to much-improved treatment balance across subgroups.

Sequential Monte Carlo for response adaptive randomized trials

Response adaptive randomized clinical trials have gained popularity due to their flexibility for adjusting design components, including arm allocation probabilities, at any point in the trial according to the intermediate results. In the Bayesian framework, allocation probabilities to different treatment arms are commonly defined as functionals of the posterior distributions of parameters of the outcome distribution for each treatment. In a non-conjugate model, however, repeated updates of the posterior distribution can be computationally intensive. In this article, we propose an adaptation of sequential Monte Carlo for efficiently updating the posterior distribution of parameters as new outcomes are observed in a general adaptive trial design. An efficient computational tool facilitates implementation of more flexible designs with more frequent interim looks that can in turn reduce the required sample size and expected number of failures in clinical trials. Moreover, more complex statistical models that reflect realistic modeling assumptions can be used for analysis of trial results.

Augmenting cognitive training in older adults (The ACT Study): Design and Methods of a Phase III tDCS and cognitive training trial

BackgroundAdults over age 65 represent the fastest growing population in the US. Decline in cognitive abilities is a hallmark of advanced age and is associated with loss of independence and dementia risk. There is a pressing need to develop effective interventions for slowing or reversing the cognitive aging process. While certain forms of cognitive training have shown promise in this area, effects only sometimes transfer to neuropsychological tests within or outside the trained domain. This paper describes a NIA-funded Phase III adaptive multisite randomized clinical trial, examining whether transcranial direct current stimulation (tDCS) of frontal cortices enhances neurocognitive outcomes achieved from cognitive training in older adults experiencing age-related cognitive decline: the Augmenting Cognitive Training in Older Adults study (ACT). MethodsACT will enroll 360 participants aged 65 to 89 with age-related cognitive decline, but not dementia. Participants will undergo cognitive training intervention or education training-control combined with tDCS or sham tDCS control. Cognitive training employs a suite of eight adaptive training tasks focused on attention/speed of processing and working memory from Posit Science BrainHQ. Training control involves exposure to educational nature/history videos and related content questions of the same interval/duration as the cognitive training. Participants are assessed at baseline, after training (12weeks), and 12-month follow-up on our primary outcome measure, NIH Toolbox Fluid Cognition Composite Score, as well as a comprehensive neurocognitive, functional, clinical and multimodal neuroimaging battery. SignificanceThe findings from this study have the potential to significantly enhance efforts to ameliorate cognitive aging and slow dementia.

Bayesian adaptive clinical trials of combination treatments.

Randomized clinical trials (RCT) increasingly investigate combination therapies. Strong biological rationale or early clinical evidence commonly suggest that the effect of the combination treatment is importantly greater than the maximum effect of any of the individual treatments. While these relationships are commonly well-accepted, RCTs do not incorporate them into the design or analysis plans. We therefore propose a simple Bayesian framework for incorporating the known relationships that the effectiveness of a combination treatment exceeds that of any individual treatment, but does not necessarily exceed the sum of individual effects. We term the collation of these two relationships ‘fractional additivity’. We performed a binary outcome simulation study of a response adaptive randomized three-arm clinical trial with treatment arms A, B, and A&B that allowed for dropping an inferior treatment arm and terminating the trial early for superiority during any of 4 interim analyses. We compared the Bayesian fractional additivity model to a conventional analysis by measuring the expected proportion of failures, sample size at trial termination, time to termination, and root mean squared error of final estimates. We also compared the fractional additivity model to a ‘full additivity’ model where the effect of A&B was assumed to be the sum of the effect of A and B. In simulation scenarios where important fractional additivity or full additivity existed, the Bayesian fractional additivity model yielded a 3–4% relative reduction in expected number of failures, and a 30%–50% relative reduction in sample size at trial termination compared to a conventional analysis. These results held true even when the Bayesian fractional additivity model employed a biased prior. The full additivity model had slightly higher gains, but too frequently terminated the trial at the first interim look. In scenarios where no or weak fractional additivity exists, the expected sample size and time to termination were similar for the Bayesian fractional additivity model with a moderately optimistic bias about fractional additivity and the conventional model. Lastly, the fractional additivity model generally yielded similar or lower root mean squared error compared to the other models. In conclusion, our proposed Bayesian fractional additivity model provides an efficient approach for estimating effects of combination treatments in clinical trials. The approach is not only highly applicable in adaptive clinical trials, but also provides added power in a conventional RCT.

Modern Adaptive Randomized Clinical Trials: Statistical and Practical Aspects

Modern Adaptive Randomized Clinical Trials: Statistical and Practical Aspects

Modern Adaptive Randomized Clinical Trials: Statistical and Practical Aspects

Modern Adaptive Randomized Clinical Trials: Statistical and Practical Aspects