A framework for applying unfamiliar trial designs in studies of rare diseases
ABSTRACT Rare diseases may be difficult to study through conventional research methods, but are amenable to study through certain uncommonly used designs. We sought to explain these designs and to provide a framework to assist researchers in identifying the most appropriate design for a given research question.
We systematically searched for literature describing rare disease research frameworks, trial designs, and trials that applied them. We present the advantages and disadvantages of each approach using these published examples, and a practical framework to help researchers in selecting between design choices.
When research participants are limited, researchers should consider using: 1) a crossover design; 2) n-of-1 trials; or 3) one of the following adaptive designs: a) a response-adaptive randomization design, b) a ranking and selection design, c) an internal pilot design,or d) a sequential design. Bayesian analysis may be applied to conventional designs, or to any of these uncommon designs. Several of these approaches may also be used in combination. The choice between methods should be guided by factors related to the intervention, disease,anticipated recruitment duration and success, and current state of knowledge about the treatment.
These techniques may facilitate research in rare diseases.
SourceAvailable from: Baziel G Van Engelen[Show abstract] [Hide abstract]
ABSTRACT: To obtain evidence for the clinical and cost-effectiveness of treatments for patients with rare diseases is a challenge. Non-dystrophic myotonia (NDM) is a group of inherited, rare muscle diseases characterized by muscle stiffness. The reimbursement of mexiletine, the expert opinion drug for NDM, has been discontinued in some countries due to a lack of independent randomized controlled trials (RCTs). It remains unclear however, which concessions can be accepted towards the level 1 evidence needed for coverage decisions, in rare diseases. Considering the large number of rare diseases with a lack of treatment evidence, more experience with innovative trial designs is needed. Both NDM and mexiletine are well suited for an N-of-1 trial design. A Bayesian approach allows for the combination of N-of-1 trials, which enables the assessment of outcomes on the patient and group level simultaneously. We will combine 30 individual, double-blind, randomized, placebo-controlled N-of-1 trials of mexiletine (600 mg daily) vs. placebo in genetically confirmed NDM patients using hierarchical Bayesian modeling. Our results will be compared and combined with the main results of an international cross-over RCT (mexiletine vs. placebo in NDM) published in 2012 that will be used as an informative prior. Similar criteria of eligibility, treatment regimen, end-points and measurement instruments are employed as used in the international cross-over RCT. The treatment of patients with NDM with mexiletine offers a unique opportunity to compare outcomes and efficiency of novel N-of-1 trial-based designs and conventional approaches in producing evidence of clinical and cost-effectiveness of treatments for patients with rare diseases. ClinicalTrials.gov Identifier: NCT02045667.BMC Neurology 03/2015; 15(1):43. DOI:10.1186/s12883-015-0294-4 · 2.49 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Definitive sample sizes for clinical trials in rare diseases are usually infeasible. Bayesian methodology can be used to maximise what is learnt from clinical trials in these circumstances. We elicited expert prior opinion for a future Bayesian randomised controlled trial for a rare inflammatory paediatric disease, polyarteritis nodosa (MYPAN, Mycophenolate mofetil for polyarteritis nodosa). A Bayesian prior elicitation meeting was convened. Opinion was sought on the probability that a patient in the MYPAN trial treated with cyclophosphamide would achieve disease remission within 6-months, and on the relative efficacies of mycophenolate mofetil and cyclophosphamide. Expert opinion was combined with previously unseen data from a recently completed randomised controlled trial in ANCA associated vasculitis. A pan-European group of fifteen experts participated in the elicitation meeting. Consensus expert prior opinion was that the most likely rates of disease remission within 6 months on cyclophosphamide or mycophenolate mofetil were 74% and 71%, respectively. This prior opinion will now be taken forward and will be modified to formulate a Bayesian posterior opinion once the MYPAN trial data from 40 patients randomised 1:1 to either CYC or MMF become available. We suggest that the methodological template we propose could be applied to trial design for other rare diseases.PLoS ONE 01/2015; 10(3):e0120981. DOI:10.1371/journal.pone.0120981 · 3.53 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: There is a need for research to understand and improve health systems for rare diseases in order to ensure that new, efficacious therapies developed through basic and early translational science lead to real benefits for patients. Such research must (i) focus on appropriate patient-oriented outcomes, (ii) include robust study designs that can accommodate real-world decision priorities, and (iii) involve effective stakeholder-engagement strategies. For transformative therapies, study outcomes will need to shift toward longer-term goals in recognition of success in preventing catastrophic outcomes. For incremental therapies, outcomes should be selected in recognition of the impact of care on quality of life for patients and families. To generate new evidence, we suggest that hybrid study designs integrating elements of practice-based observational research and pragmatic trials hold the most promise for addressing priorities such as minimizing bias, accounting for cointerventions, identifying long-term impacts, and considering clinical heterogeneity. To effectively engage with stakeholders, a knowledge exchange infrastructure is needed to foster collaboration among patients with rare diseases and their families, health-care providers, researchers, and policy decision makers. A key priority for these groups must be collaboration toward a shared understanding of the outcomes that are of most relevance to the facilitation of patient-centered care.Genetics in medicine: official journal of the American College of Medical Genetics 04/2015; DOI:10.1038/gim.2015.42 · 6.44 Impact Factor