Ethics of placebo use in pediatric clinical trials: the case of antihypertensive drug studies

Protocol for the Vitamin D Oral Replacement in Asthma (VDORA) study

Obesity and asthma are epidemic in the United States and obesity is an independent risk factor for asthma. Low vitamin D levels (i.e. serum 25-hydroxyvitamin D) have been reported in patients with reduced lung function, more frequent respiratory infections, and asthma exacerbations. Experts have proposed that serum levels > 40 ng/mL are required to offer the immunomodulatory benefits of vitamin D. Low vitamin D levels are common in both obesity and asthma, but it is not known whether supplementation with vitamin D improves asthma symptoms. Guidance for drug development stresses the importance of early phase studies to establish accurate population pharmacokinetics (PK) and drug dosing prior to larger phase 3 trials. The PK of this fat-soluble vitamin in children with increased adiposity are unknown; as are the doses need to reach proposed immunomodulatory levels. The objective of this study is to characterize the PK of vitamin D in children with obesity. Children ages 6--18 years who had physician diagnosed asthma and a body mass index (BMI) >85th percentile will be randomized to receive either standard daily dosing or loading doses followed by standard daily dosing. Blood samples will be obtained to characterize the PK of vitamin D. The results of this study will be used to identify a sufficient dose of vitamin D supplement to raise serum levels above a pre-specified value that may result in anti-inflammatory actions that could improve asthma symptoms.

Use of Placebo in Supplementation Studies-Vitamin D Research Illustrates an Ethical Quandary

History has shown that without explicit and enforced guidelines, even well-intentioned researchers can fail to adequately examine the ethical pros and cons of study design choices. One area in which consensus does not yet exist is the use of placebo groups in vitamin supplementation studies. As a prime example, we focus on vitamin D research. We aim to provide an overview of the ethical issues in placebo-controlled studies and guide future discussion about the ethical use of placebo groups. Research in the field of vitamin D shows variation in how placebo groups are used. We outline four types of control groups in use: active-control, placebo-control with restrictions on supplementation, placebo-control without supplementation restrictions, and placebo-control with rescue repletion therapy. The first two types highlight discrete ethical issues: active-control trials limit the ability to detect a difference; placebo-control trials that restrict supplementation potentially place subjects at risk of undue harm. The final two, placebo-control without supplementation restrictions or with rescue repletion therapy, offer potential solutions to these ethical challenges. Building on this, guidelines should be established and enforced on the use of placebo in supplementation studies. Furthermore, the field of vitamin D research has the potential to set an example worthy of emulation.

Clinical trials in children

Safety and efficacy data on many medicines used in children are surprisingly scarce. As a result children are sometimes given ineffective medicines or medicines with unknown harmful side effects. Better and more relevant clinical trials in children are needed to increase our knowledge of the effects of medicines and to prevent the delayed or non-use of beneficial therapies. Clinical trials provide reliable evidence of treatment effects by rigorous controlled testing of interventions on human subjects. Paediatric trials are more challenging to conduct than trials in adults because of the paucity of funding, uniqueness of children and particular ethical concerns. Although current regulations and initiatives are improving the scope, quantity and quality of trials in children, there are still deficiencies that need to be addressed to accelerate radically equitable access to evidence-based therapies in children.

A multicenter study of neurocognition in children with hypertension: methods, challenges, and solutions

Hypertensive adults demonstrate decreased performance on neurocognitive testing compared with that of normotensive controls. There is now emerging, preliminary evidence that children with hypertension also manifest neurocognitive differences when compared with normotensive controls, findings postulated to potentially represent early signs of hypertensive target organ damage to the brain. However, reports in children to date have been limited to database and single-center studies. We have established an ongoing, prospective, multicenter study of neurocognition in children with primary hypertension. This article outlines the study methods, with particular attention to the unique challenges in this area of clinical research. We highlight aspects of the study design that are specifically designed as solutions to these challenges.

Effect of placebo on ambulatory blood pressure monitoring in children

BACKGROUND

Ambulatory blood pressure monitoring (ABPM) has been proposed as a useful tool for more accurately diagnosing hypertension (HTN) and evaluating blood pressure (BP) response in pediatric anti-hypertensive trials. ABPM captures multiple BP measurements during routine daily activities and is thus an excellent method for identifying white-coat HTN. Additionally, ABPM measurements in adults do not demonstrate the placebo effect commonly seen with casual BP measurements, although this has yet to be evaluated in children. Therefore,, the aim of this study was to assess the effect of placebo on ABPM measurements in children.

METHODS

A total of 141 children aged 5-16 years with elevated BP were randomized into a multi-center, single-blind, cross-over trial. Subjects received a placebo pill prior to wearing a 24-h ABPM device at one of two visits separated by 1-2 weeks. Study procedures were otherwise identical at both visits.

RESULTS

Mean systolic and diastolic BP for all measured time periods were similar between visits, as was the number of children diagnosed with HTN at each visit.

CONCLUSION

Having confirmed HTN at baseline did not affect the impact of placebo on mean BP. If confirmed, this lack of placebo effect on ABPM measurements may allow for the design of direct comparison pediatric anti-hypertensive trials without a placebo arm.

When ethics constrains clinical research: trial design of control arms in "greater than minimal risk" pediatric trials

For more than three decades clinical research in the United States has been explicitly guided by the idea that ethical considerations must be central to research design and practice. In spite of the centrality of this idea, attempting to balance the sometimes conflicting values of advancing scientific knowledge and protecting human subjects continues to pose challenges. Possible conflicts between the standards of scientific research and those of ethics are particularly salient in relation to trial design. Specifically, the choice of a control arm is an aspect of trial design in which ethical and scientific issues are deeply entwined. Although ethical quandaries related to the choice of control arms may arise when conducting any type of clinical trials, they are conspicuous in early phase gene transfer trials that involve highly novel approaches and surgical procedures and have children as the research subjects. Because of children's and their parents' vulnerabilities, in trials that investigate therapies for fatal, rare diseases affecting minors, the scientific and ethical concerns related to choosing appropriate controls are particularly significant. In this paper we use direct gene transfer to the central nervous system to treat late infantile neuronal ceroid lipofuscinosis to illustrate some of these ethical issues and explore possible solutions to real and apparent conflicts between scientific and ethical considerations.

Frontline ethical issues in pediatric clinical research: ethical and regulatory aspects of seven current bottlenecks in pediatric clinical research

In the course of the past decades, considerable effort has been expended on the ethical guidance and legal regulation of pediatric clinical trials in Europe. Nonetheless, the conduct of clinical research in the population of minors continues to generate myriad ethical and regulatory issues. This paper explores seven bottlenecks in the ethical guidance and legal regulation that currently govern pediatric clinical research: (1) the integration of research in therapy, (2) the education of clinicians, (3) the empowerment of families, (4) the harmonization of protocol review, (5) the assessment non-clinical research objectives, (6) the control of placebo use, and (7) the provision of fair incentives for pediatric research conduct. For all of these issues, a clear view on the way forward is largely lacking, either because these issues have not been discussed in depth to date or because the existing debates have failed to generate a generally supported consensus.

Efficacy and safety of angiotensin II receptor type 1 antagonists in children and adolescents

Our purpose was to evaluate the effects of angiotensin II receptor type 1 antagonists (ARAs) in children and adolescents with hypertension or/and several kinds of nephropathies on blood pressure (BP) and proteinuria and to evaluate related safety issues. Data sources were Medline, Embase, The Cochrane Library, BIOSIS Previews, contact with investigators and manufacturers, personal bibliography of the lead author, and manual searches. We selected randomized controlled trials (RCTs), uncontrolled trials, and case series investigating ARAs in children and adolescents, as well as case reports about adverse events and the embryotoxic effects of ARAs in children. In four RCTs with 698 individuals, mean systolic blood pressure (BP) decreased by 10.5 mmHg [95% confidence interval (CI) 9.8-11.2] and mean diastolic BP by 6.4 mmHg (95% CI 5.8-7.0). Proteinuria decreased by 30-64% (range) in two RCTs and four case series. Safety data were comparable with adult safety data. ARAs can be considered effective and safe in lowering BP and proteinuria in the pediatric age group. The correlation between the surrogate parameters BP and proteinuria with clinical endpoints is documented to a large degree. The evidence is based on RCTs and also on lower evidence levels, such as case series. In some conditions, RCTs in children are not feasible. Registers could provide more evidence in the future.

Pediatric antihypertensive trial failures: analysis of end points and dose range

Historically, drugs prescribed for children have not been studied in pediatric populations. Since 1997, however, a 6-month extension of marketing rights is granted if manufacturers conduct Food and Drug Administration-defined pediatric trials. In nearly half of the drugs studied, there were unexpected results in dosing, safety, or efficacy compared with adult studies, including failure of half of the antihypertensive dose-response trials, which are pivotal for deriving dosing recommendations. We sought to define design elements that might have contributed to these trial failures by combining patient-level data from 6 dose-ranging antihypertensive efficacy trials completed for pediatric exclusivity and submitted to the Food and Drug Administration from 1998 to 2005. We evaluated dosing, primary end point, and other components to assess underlying reasons for failure to show efficacy in children. Of 6 trials examined, 3 showed a dose response; 3 did not. Eligibility criteria were similar across studies, as were subject demographics. Successful studies showed large differences in doses, with little or no overlap between low, medium, and high doses; failed trials used narrow dose ranges with considerable overlap. Successful trials also provided pediatric formulations and used reduction in diastolic, not systolic, blood pressure as the primary end point. Careful attention to pediatric pharmacology and selection of primary end points can improve trial performance. We found poor dose selection, lack of acknowledgement of differences between adult and pediatric populations, and lack of pediatric formulations to be associated with failures. More importantly, our ability to combine data across trials allowed us to evaluate and potentially improve trial design.

Efficacy and safety of extended release metoprolol succinate in hypertensive children 6 to 16 years of age: a clinical trial experience

OBJECTIVE

To evaluate the efficacy, tolerability, and blood pressure (BP) lowering effect of extended release metoprolol succinate (ER metoprolol) in children 6 to 16 years of age with established hypertension.

STUDY DESIGN

Patients were randomized to one of four treatment arms: placebo or ER metoprolol (0.2 mg/kg, 1.0 mg/kg, or 2.0 mg/kg). Data were analyzed on 140 intent-to-treat patients.

RESULTS

Mean age (+/-SD) was 12.5 +/- 2.8 years and mean baseline BP was 132/78 +/- 9/9 mmHg. Following 4 weeks of treatment, mean changes in sitting BP were: placebo = -1.9/-2.1 mmHg; ER metoprolol 0.2 mg/kg = -5.2/-3.1 mmHg; 1.0 mg/kg = -7.7/-4.9 mmHg; 2.0 mg/kg = -6.3/-7.5 mmHg. Compared with placebo, ER metoprolol significantly reduced systolic blood pressure (SBP) at the 1.0 and 2.0 mg/kg dose (P = .027 and P = .049, respectively), reduced diastolic blood pressure (DBP) at the 2.0 mg/kg dose (P = .017), and showed a statistically significant dose response relationship for the placebo-corrected change in DBP from baseline. There were no serious adverse events or adverse events requiring study drug discontinuation among patients receiving active therapy.

CONCLUSION

These data indicate that ER metoprolol is an effective and well-tolerated treatment for hypertension in children.

Drug trials in pediatric heart failure: hype or improved clinical science?

The evidence available from which to guide therapy for pediatric heart failure is limited. Although there are many reasons for this, the greatest obstacles in developing this evidence base are due to the significant challenges inherent in performing well-designed drug trials in pediatric heart failure. This perspective will define many of these obstacles and will propose potential structures for the development and implementation of drug trials in pediatric heart failure.

Ethical considerations in research involving children

Ethical concerns and medical advances unique to children and adolescents make pediatric research an evolving endeavor. The child's changing physiology from infancy to maturity requires understanding of the benefits and risks of medical therapies currently available, but often not tested in children, as well as the risks and benefits of inclusion of children in clinical research. Recent mandates from the US Food and Drug Administration (FDA) require that drugs be tested for safety and efficacy in children. Growing concern for the prevalence of chronic disorders and increasing understanding of distinct phenotypes of these disorders points to a likely need for unique interventions matched to specific phenotypes. All contribute to the increasing complexity of ethical considerations in pediatric research.

Pharmacovigilance during the Pre-Approval Phases

Pharmacovigilance science has traditionally been a discipline focussed on the postmarketing or post-authorisation period, with due attention directed towards pre-clinical safety data, clinical trials and adverse events. As the biological sciences have evolved, pharmacovigilance has slowly shifted toward earlier, proactive consideration of risks and potential benefits of drugs in the pre- and peri-approval stages of drug development, leading to a maturing of drug safety risk management. Further advances in biology, pharmacology and improvements in computational applications to medicine have led to the development of more complex medicines previously unobtainable and have also permitted a more thorough assessment of risks and potential benefits even earlier in the development process. Elevated public concern with the safety of more sophisticated medicines, combined with new science, have led pharmaceutical innovators, regulators and healthcare professionals to collaborate to develop guidelines, which drive enhanced pharmacovigilance and safety risk management earlier in drug development. In this paper, we review international guidelines on pharmacovigilance planning applicable to the pre-approval phases of medicines development and provide author opinion on these guidelines' potential drug safety implications. We discuss the possible evolution of a pharmaceutical industry model to respond to these guidelines; a view on multidisciplinary safety management teams is provided to encourage refinement of safety-signal identification and risk assessment early in drug development and to communicate important safety concerns to internal research efforts, patients, investigators and regulators. We further describe these functions in the context of the complexities of vulnerable populations, including the example of medicines research for paediatric populations. We also discuss the special role of epidemiology in pre-approval drug development and the impact on epidemiological science of changes to the pharmacovigilance paradigm.

Analgesia and anesthesia for neonates: Study design and ethical issues

OBJECTIVE

The purpose of this article is to summarize the clinical, methodologic, and ethical considerations for researchers interested in designing future trials in neonatal analgesia and anesthesia, hopefully stimulating additional research in this field.

METHODS

The MEDLINE, PubMed, EMBASE, and Cochrane register databases were searched using subject headings related to infant, newborn, neonate, analgesia, anesthesia, ethics, and study design. Cross-references and personal files were searched manually. Studies reporting original data or review articles related to these topics were assessed and critically evaluated by experts for each topical area. Data on population demographics, study characteristics, and cognitive and behavioral outcomes were abstracted and synthesized in a systematic manner and refined by group members. Data synthesis and results were reviewed by a panel of independent experts and presented to a wider audience including clinicians, scientists, regulatory personnel, and industry representatives at the Newborn Drug Development Initiative workshop. Recommendations were revised after extensive discussions at the workshop and between committee members.

RESULTS

Designing clinical trials to investigate novel or currently available approaches for analgesia and anesthesia in neonates requires consideration of salient study designs and ethical issues. Conditions requiring treatment include pain/stress resulting from invasive procedures, surgical operations, inflammatory conditions, and routine neonatal intensive care. Study design considerations must define the inclusion and exclusion criteria, a rationale for stratification, the confounding effects of comorbid conditions, and other clinical factors. Significant ethical issues include the constraints of studying neonates, obtaining informed consent, making risk-benefit assessments, defining compensation or rewards for participation, safety considerations, the use of placebo controls, and the variability among institutional review boards in interpreting federal guidelines on human research. For optimal study design, investigators must formulate well-defined study questions, choose appropriate trial designs, estimate drug efficacy, calculate sample size, determine the duration of the studies, identify pharmacokinetic and pharmacodynamic parameters, and avoid drug-drug interactions. Specific outcome measures may include scoring on pain assessment scales, various biomarkers and their patterns of response, process outcomes (eg, length of stay, time to extubation), intermediate or long-term outcomes, and safety parameters.

CONCLUSIONS

Much more research is needed in this field to formulate a scientifically sound, evidence-based, and clinically useful framework for management of anesthesia and analgesia in neonates. Newer study designs and additional ethical dilemmas may be defined with accumulating data in this field.

Informed consent in pediatric clinical trials

PURPOSE OF REVIEW

Clinical research in children is increasing. Concerns have been raised about both the inclusion and the exclusion of children in such research. Corresponding to these concerns, issues in informed consent for pediatric trials have become more pressing. This review discusses informed consent in pediatric trials and characterizes the latest literature.

RECENT FINDINGS

Research into the consent process has shown that central concepts in pediatric research such as randomization and the distinctions between phases of clinical trials are not uniformly understood by parents or older pediatric patients. Newer approaches that are being developed to help remedy these deficits include the use of staged informed consent, the incorporation of interactive computer technologies to convey complex ideas, and variations in approaches to assent of the child based on multifactorial assessments of competence. Other variables in the consent process that are being studied for their impact on the process include individual life experiences and cultural background. Gaps in federal regulation and oversight of "informed consent" are emerging as new cases test established assumptions.

SUMMARY

Lessons learned from recent studies regarding oversight of the consent process in pediatric clinical trials, the complex nature of assent, the impact of cultural variables, and more effective means of communicating what is involved in a clinical trial will shape future studies in consent and help to improve the process.

Antihypertensive and antiproteinuric efficacy of ramipril in children with chronic renal failure

BACKGROUND

While the antihypertensive and renoprotective potency of angiotensin-converting enzyme (ACE) inhibitors is well-established in adults with hypertension and/or chronic renal failure, little experience exists in pediatric chronic kidney disease.

METHODS

As part of a prospective assessment of the renoprotective efficacy of ACE inhibition and intensified blood pressure (BP) control, 397 children (ages 3 to 18 years) with chronic renal failure [CRF; glomerular filtration rate (GFR) 11 to 80 mL/min/1.73 m2] and elevated or high-normal BP received ramipril (6 mg/m2) following a 6-month run-in period including a two-month washout of any previous ACE inhibitors. Drug efficacy was assessed by two monthly office BP and proteinuria assessments, and by ambulatory BP monitoring at start and after 6 months of treatment.

RESULTS

In the 352 patients completing six months of treatment, 24-hour mean arterial pressure (MAP) had decreased by a mean of 11.5 mm Hg (-2.2 SDS) in initially hypertensive subjects, but only by 4.4 mm Hg (-0.8 SDS) in patients with initially normal BP. A linear correlation was found between MAP at baseline and the change of MAP during treatment (r= 0.51; P < 0.0001). The antihypertensive response was independent of changes in concomitant antihypertensive medication or underlying renal disease. BP was reduced with equal efficacy during day- and nighttime. Urinary protein excretion was reduced by 50% on average, with similar relative efficacy in patients with hypo/dysplastic nephropathies and glomerulopathies. The magnitude of proteinuria reduction depended on baseline proteinuria (r= 0.32, P < 0.0001), and was correlated with the antihypertensive efficacy of the drug (r= 0.22, P < 0.001). The incidence of rapid rises in serum creatinine and progression to end-stage CRF during treatment did not differ from the pretreatment observation period. Mean serum potassium increased by 0.3 mmol/L. Ramipril was discontinued in three patients due to symptomatic hypotension or hyperkalemia. Hemoglobin levels decreased by 0.6 g/dL in the first two treatment months and remained stable thereafter.

CONCLUSION

Ramipril appears to be an effective and safe antihypertensive and antiproteinuric agent in children with CRF-associated hypertension. The BP lowering and antiproteinuric effects are greatest in severely hypertensive and proteinuric children.