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A pragmatic, adaptive clinical trial design for a rare disease: The FOcal Cerebral Arteriopathy Steroid (FOCAS) trial.

ABSTRACT: BACKGROUND:Pediatric stroke investigators identified as their top research priority a clinical trial of corticosteroids for focal cerebral arteriopathy (FCA). However, FCA is both rare and an acute condition making it infeasible to enroll the large sample sizes needed for standard, confirmatory clinical trials. We present a pragmatic approach to clinical trial design that may inform the approach to other rare disorders. METHODS:We surveyed pediatric stroke experts to determine the level of evidence that would impact their clinical management of FCA. Incorporating survey results, a randomized, group sequential Bayesian adaptive design was proposed based on a quantitative radiologic outcome measure (change from baseline in change in the FCA Severity Score). Using accumulating information, the design determines whether intervention is better than control with high probability. RESULTS:Among 21 (100%) respondents, the probability of corticosteroid efficacy that would lead the experts to treat was 30% (median). The probability of efficacy that would make them unwilling to randomize (because they would feel all children should receive corticosteroids) was 70%. Simulation studies with the proposed design showed that a total of 42 subjects controls the type I error rate at the desired level 0.20 and yields a smaller average sample size and trial duration compared to a conventional design. CONCLUSIONS:Designs in rare diseases require special considerations; this is especially true for this childhood disease, which is both uncommon and acute. This design has incorporated expert consensus to establish the criteria for success, formal monitoring rules for safety, and early stopping rules.

SUBMITTER: Park Y

PROVIDER: S-EPMC6857809 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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A pragmatic, adaptive clinical trial design for a rare disease: The FOcal Cerebral Arteriopathy Steroid (FOCAS) trial.

Park Yeonhee Y Fullerton Heather J HJ Elm Jordan J JJ

Contemporary clinical trials 20191013

<h4>Background</h4>Pediatric stroke investigators identified as their top research priority a clinical trial of corticosteroids for focal cerebral arteriopathy (FCA). However, FCA is both rare and an acute condition making it infeasible to enroll the large sample sizes needed for standard, confirmatory clinical trials. We present a pragmatic approach to clinical trial design that may inform the approach to other rare disorders.<h4>Methods</h4>We surveyed pediatric stroke experts to determine the ...[more]

PMID: 31614215

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Project description:BACKGROUND:A key challenge in phase I trials is maintaining rapid escalation in order to avoid exposing too many patients to sub-therapeutic doses, while preserving safety by limiting the frequency of toxic events. Traditional rule-based designs require temporarily stopping recruitment whilst waiting to see whether enrolled patients develop toxicity. This can be both inefficient and introduces logistic challenges to recruitment in the clinic. We describe a novel two-stage dose assignment procedure designed for a phase I clinical trial (STARPAC), where a good estimation of prior was possible. METHODS:The STARPAC design uses rule-based design until the first patient has a dose limiting toxicity (DLT) and then switches to a modified CRM, with rules to handle patient recruitment during follow-up of earlier patients. STARPAC design is compared via simulations with the TITE-CRM and 3?+?3 methods in various toxicity estimate (T1-5), rate of recruitment (R1-2), and DLT events timing (DT1-4), scenarios using several metrics: accuracy of maximum tolerated dose (MTD), numbers of DLTs, number of patients enrolled and those missed; duration of trial; and proportion of patients treated at the therapeutic dose or MTD. RESULTS:The simulations suggest that STARPAC design performed well in MTD estimation and in treating patients at the highest possible therapeutic levels. STARPAC and TITE-CRM were comparable in the number of patients required and DLTs incurred. The 3?+?3 design often had fewer patients and DLTs although this is due to its low escalation rate leading to poor MTD estimation. For the numbers of declined patients and MTD estimation 3?+?3 is uniformly worse, with STARPAC being better in those metrics for high toxicity scenarios and TITE-CRM better with low toxicity. In situations including doses with toxicities both above and below 30%, the STARPAC design outperformed TITE-CRM with respect to every metric. CONCLUSION:When considering doses with toxicities both above and below the target of 30% toxicities, the two-stage STARPAC dose escalation design provides a more efficient phase I trial design than either the traditional 3?+?3 or the TITE-CRM design. Trialists should model various designs via simulation to adopt the most efficient design for their clinical scenario. TRIAL REGISTRATION:Clinical Trials NCT03307148 (11 October 2017).

Project description:BackgroundThe prescribing of high-risk medications to older adults remains extremely common and results in potentially avoidable health consequences. Efforts to reduce prescribing have had limited success, in part because they have been sub-optimally timed, poorly designed, or not provided actionable information. Electronic health record (EHR)-based tools are commonly used but have had limited application in facilitating deprescribing in older adults. The objective is to determine whether designing EHR tools using behavioral science principles reduces inappropriate prescribing and clinical outcomes in older adults.MethodsThe Novel Uses of Designs to Guide provider Engagement in Electronic Health Records (NUDGE-EHR) project uses a two-stage, 16-arm adaptive randomized pragmatic trial with a "pick-the-winner" design to identify the most effective of many potential EHR tools among primary care providers and their patients ? 65?years chronically using benzodiazepines, sedative hypnotic ("Z-drugs"), or anticholinergics in a large integrated delivery system. In stage 1, we randomized providers and their patients to usual care (n = 81 providers) or one of 15 EHR tools (n = 8 providers per arm) designed using behavioral principles including salience, choice architecture, or defaulting. After 6?months of follow-up, we will rank order the arms based upon their impact on the trial's primary outcome (for both stages): reduction in inappropriate prescribing (via discontinuation or tapering). In stage 2, we will randomize (a) stage 1 usual care providers in a 1:1 ratio to one of the up to 5 most promising stage 1 interventions or continue usual care and (b) stage 1 providers in the unselected arms in a 1:1 ratio to one of the 5 most promising interventions or usual care. Secondary and tertiary outcomes include quantities of medication prescribed and utilized and clinically significant adverse outcomes.DiscussionStage 1 launched in October 2020. We plan to complete stage 2 follow-up in December 2021. These results will advance understanding about how behavioral science can optimize EHR decision support to improve prescribing and health outcomes. Adaptive trials have rarely been used in implementation science, so these findings also provide insight into how trials in this field could be more efficiently conducted.Trial registrationClinicaltrials.gov ( NCT04284553 , registered: February 26, 2020).

Dataset Information

A pragmatic, adaptive clinical trial design for a rare disease: The FOcal Cerebral Arteriopathy Steroid (FOCAS) trial.

Publications

A pragmatic, adaptive clinical trial design for a rare disease: The FOcal Cerebral Arteriopathy Steroid (FOCAS) trial.

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