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

Be aware of childhood stroke: Proceedings from EPNS Webinar

Childhood arterial ischaemic stroke (AIS) is a significant health concern with increasing incidence. This review aims to provide an overview of the current understanding of childhood AIS. The incidence of childhood AIS is on the rise especially in developing countries, likely due to improved awareness and diagnostic capabilities. Aetiology of childhood AIS is multifactorial, with both modifiable risk factors and genetic predisposition playing important roles. Identifying and addressing these risk factors, such as infection, sickle cell disease, and congenital heart defects, is essential in prevention and management. Identifying underlying conditions through genetic testing is important for appropriate management and long-term prognosis. Clinically, distinguishing stroke from stroke mimics can be challenging. Awareness of important stroke mimics, including migraines, seizures, and metabolic disorders, is crucial to avoid misdiagnosis and ensure appropriate treatment. The diagnostic approach to childhood AIS involves a comprehensive "chain of care," including initial assessment, neuroimaging, and laboratory investigations. National guidelines play a pivotal role in standardizing and streamlining the diagnostic process, ensuring prompt and accurate management. Early intervention is critical in the management of childhood AIS. Due to the critical time window, the question if mechanical thrombectomy is feasible and beneficial should be addressed as fast as possible. Early initiation of antiplatelet or anticoagulation therapy and, in select cases, thrombolysis can help restore blood flow and minimize long-term neurological damage. Additionally, rehabilitation should start as soon as possible to optimize recovery and improve functional outcomes. In conclusion, childhood AIS is a growing concern. Understanding the increasing incidence, age distribution, risk factors, clinical presentation, diagnostic approach, and management strategies is crucial for optimized management of these patients.

Stroke in the young

PURPOSE OF REVIEW

The purpose of this review is to review recent findings regarding stroke epidemiology, etiologies, and treatment in children and young adults.

RECENT FINDINGS

Incidence in young adults is increasing, and incidence, recurrence, and survival is worse in patients with cryptogenic stroke and in developing countries. Careful consideration of patent foramen ovale closure is now recommended in young adults with cryptogenic stroke. Thrombectomy has recently been extended to carefully selected children with acute ischemic stroke, and two recent publications strongly suggest that it can be beneficial for children. Sickle cell is also an important global contributor to stroke burden, but hydroxyurea can be a cost effective medication for stroke prevention in children. Recent advances in genetic testing and treatments may improve outcomes for patients with monogenic causes of stroke, such as deficiency of adenosine deaminase 2, hemophilia, and Fabry's disease.

SUMMARY

Stroke in children and young adults is a morbid disease responsible for enormous indirect societal costs and a high burden of years with disability per affected patient. Recent advances have improved access to care for children with large vessel occlusion and adults with rare causes of stroke. Future research may bring effective treatments for other monogenic causes of stroke as well as increasing access to hyperacute therapies for young stroke patients.

Pediatric Ischemic Stroke

OBJECTIVE

Pediatric cerebrovascular disease is one of the leading causes of death and disability in children. Survivors of childhood stroke and their families are often left to cope with long-lasting sequelae, such as barriers to school reentry and long-term challenges in attaining independence as adults. Because childhood stroke is rare and providers may not be familiar with the disorder, this article reviews the risk factors, acute management, and sequelae of ischemic stroke in children.

LATEST DEVELOPMENTS

High-quality evidence has resulted in an organized approach to emergent treatment of ischemic stroke in adults, but most front-line providers are less prepared for emergent stroke management in children. The level of evidence for reperfusion therapies in children remains low but is growing. Thrombolysis and thrombectomy are sometimes considered for hyperacute treatment of stroke in children. Readiness for pediatric stroke at regional centers should include an organized approach to pediatric stroke triage and management based on extrapolation from adult stroke trials, expert consensus, and emerging pediatric studies.

ESSENTIAL POINTS

This review provides up-to-date information about ischemic stroke risk factors and management in children. Preparation for rapid stroke diagnosis and management in children may improve outcomes.

Cerebral Arteriopathies of Childhood - Current Approaches

Up to more than half of previously healthy children presenting with their first arterial ischemic stroke have a cerebral arteriopathy. Cerebral arteriopathies during childhood can be congenital, reflecting abnormal vessel development, or acquired when caused by disruption of vascular homeostasis. Distinguishing different types of cerebral arteriopathies in children can be challenging but of great clinical value as they may dictate different disease and treatment courses, and clinical and radiologic outcomes. Furthermore, children with stroke due to a specific arteriopathy exhibit distinctive features when compared to those with stroke due to other causes or a different type of arteriopathy. These features become crucial in the management of pediatric stroke by choosing appropriate diagnostic and treatment strategies. The objective of this article is to provide the reader with a comprehensive up-to-date review of the classification, symptoms, diagnosis, treatment, and outcome of cerebral arteriopathies in children.

Acute Hospital Management of Pediatric Stroke

The field of pediatric stroke has historically been hampered by limited evidence and small patient cohorts. However the landscape of childhood stroke is rapidly changing due in part to increasing awareness of the importance of pediatric stroke and the emergence of dedicated pediatric stroke centers, care pathways, and alert systems. Acute pediatric stroke management hinges on timely diagnosis confirmed by neuroimaging, appropriate consideration of recanalization therapies, implementation of neuroprotective measures, and attention to secondary prevention. Because pediatric stroke is highly heterogenous in etiology, management strategies must be individualized. Determining a child's underlying stroke etiology is essential to appropriately tailoring hyperacute stroke management and determining best approach to secondary prevention. Herein, we review the methods of recognition, diagnosis, management, current knowledge gaps and promising research for pediatric stroke.

Application of Bayesian methods to accelerate rare disease drug development: scopes and hurdles

Background

Design and analysis of clinical trials for rare and ultra-rare disease pose unique challenges to the practitioners. Meeting conventional power requirements is infeasible for diseases where sample sizes are inherently very small. Moreover, rare disease populations are generally heterogeneous and widely dispersed, which complicates study enrollment and design. Leveraging all available information in rare and ultra-rare disease trials can improve both drug development and informed decision-making processes.

Main text

Bayesian statistics provides a formal framework for combining all relevant information at all stages of the clinical trial, including trial design, execution, and analysis. This manuscript provides an overview of different Bayesian methods applicable to clinical trials in rare disease. We present real or hypothetical case studies that address the key needs of rare disease drug development highlighting several specific Bayesian examples of clinical trials. Advantages and hurdles of these approaches are discussed in detail. In addition, we emphasize the practical and regulatory aspects in the context of real-life applications.

Conclusion

The use of innovative trial designs such as master protocols and complex adaptive designs in conjunction with a Bayesian approach may help to reduce sample size, select the correct treatment and population, and accurately and reliably assess the treatment effect in the rare disease setting.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02342-5.

Personalized Risk-Based Screening Design for Comparative Two-Arm Group Sequential Clinical Trials

Personalized medicine has been emerging to take into account individual variability in genes and environment. In the era of personalized medicine, it is critical to incorporate the patients’ characteristics and improve the clinical benefit for patients. The patients’ characteristics are incorporated in adaptive randomization to identify patients who are expected to get more benefit from the treatment and optimize the treatment allocation. However, it is challenging to control potential selection bias from using observed efficacy data and the effect of prognostic covariates in adaptive randomization. This paper proposes a personalized risk-based screening design using Bayesian covariate-adjusted response-adaptive randomization that compares the experimental screening method to a standard screening method based on indicators of having a disease. Personalized risk-based allocation probability is built for adaptive randomization, and Bayesian adaptive decision rules are calibrated to preserve error rates. A simulation study shows that the proposed design controls error rates and yields a much smaller number of failures and a larger number of patients allocated to a better intervention compared to existing randomized controlled trial designs. Therefore, the proposed design performs well for randomized controlled clinical trials under personalized medicine.

Childhood stroke

Stroke is an important cause of neurological morbidity in children; most survivors have permanent neurological deficits that affect the remainder of their life. Stroke in childhood, the focus of this Primer, is distinguished from perinatal stroke, defined as stroke before 29 days of age, because of its unique pathogenesis reflecting the maternal-fetal unit. Although approximately 15% of strokes in adults are haemorrhagic, half of incident strokes in children are haemorrhagic and half are ischaemic. The causes of childhood stroke are distinct from those in adults. Urgent brain imaging is essential to confirm the stroke diagnosis and guide decisions about hyperacute therapies. Secondary stroke prevention strongly depends on the underlying aetiology. While the past decade has seen substantial advances in paediatric stroke research, the quality of evidence for interventions, such as the rapid reperfusion therapies that have revolutionized arterial ischaemic stroke care in adults, remains low. Substantial time delays in diagnosis and treatment continue to challenge best possible care. Effective primary stroke prevention strategies in children with sickle cell disease represent a major success, yet barriers to implementation persist. The multidisciplinary members of the International Pediatric Stroke Organization are coordinating global efforts to tackle these challenges and improve the outcomes in children with cerebrovascular disease.

Design and analysis features used in small population and rare disease trials: A targeted review

OBJECTIVE

Frequentist trials in Rare disease/small population trials often require unfeasibly large sample size to detect minimum clinically important differences. A targeted review was performed investigating what design and analysis methods these trials use when facing restricted recruitment.

STUDY DESIGN AND SETTING

Targeted Review searching EMBASE and MEDLINE for Phase II-IV RCTs reporting 'rare' disease or 'small population' within title or abstract, since 2009.

RESULTS

A total of 6,128 articles were screened with 64 trials eligible (4 Bayesian, 60 frequentist trials). Frequentists trials had planned power ranging 72-90% (median: 80%) but reported recruiting a mean of 6.6% below the planned sample size (n=38) [median 0%, IQR (-5%, 5%)], most used standard type 1 error (52 used 5% and 1 used 1%), and the average standardised effect was high (0.7) with 50% missing their assumed level. Of the 4 Bayesian trials, 3 used informed priors, 2 and 1 trials performed sensitivity analysis for the impact of priors on design and analysis respectively. Historical data, expert consensus, or both were used to construct informative priors. Bayesian trials required 30%-2400% less participants than using frequentist frameworks.

CONCLUSION

Bayesian trials required lower sample size through use of informative priors. Most frequentists didn't achieve their target sample size. Bayesian methods offer promising solutions for such trials but are underutilised.

Definitive Diagnostic Evaluation of the Child With Arterial Ischemic Stroke and Approaches to Secondary Stroke Prevention

ABSTRACT

In children with arterial ischemic stroke (AIS), the definitive diagnosis of stroke subtype and confirmation of stroke etiology is necessary to mitigate stroke morbidity and prevent recurrent stroke. The common causes of AIS in children are sharply differentiated from the common causes of adult AIS. A comprehensive, structured diagnostic approach will identify the etiology of stroke in most children. Adequate diagnostic evaluation relies on advanced brain imaging and vascular imaging studies. A variety of medical and surgical secondary stroke prevention strategies directed at the underlying cause of stroke are available. This review aims to outline strategies for definitive diagnosis and secondary stroke prevention in children with AIS, emphasizing the critical role of neuroimaging.