Outcomes in pediatric studies of medium-chain acyl-coA dehydrogenase (MCAD) deficiency and phenylketonuria (PKU): a review

Assessing the quality and value of metabolic chart data for capturing core outcomes for pediatric medium-chain acyl-CoA dehydrogenase (MCAD) deficiency

BACKGROUND

Generating rigorous evidence to inform care for rare diseases requires reliable, sustainable, and longitudinal measurement of priority outcomes. Having developed a core outcome set for pediatric medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, we aimed to assess the feasibility of prospective measurement of these core outcomes during routine metabolic clinic visits.

METHODS

We used existing cohort data abstracted from charts of 124 children diagnosed with MCAD deficiency who participated in a Canadian study which collected data from birth to a maximum of 11 years of age to investigate the frequency of clinic visits and quality of metabolic chart data for selected outcomes. We recorded all opportunities to collect outcomes from the medical chart as a function of visit rate to the metabolic clinic, by treatment centre and by child age. We applied a data quality framework to evaluate data based on completeness, conformance, and plausibility for four core MCAD outcomes: emergency department use, fasting time, metabolic decompensation, and death.

RESULTS

The frequency of metabolic clinic visits decreased with increasing age, from a rate of 2.8 visits per child per year (95% confidence interval, 2.3-3.3) among infants 2 to 6 months, to 1.0 visit per child per year (95% confidence interval, 0.9-1.2) among those ≥ 5 years of age. Rates of emergency department visits followed anticipated trends by child age. Supplemental findings suggested that some emergency visits occur outside of the metabolic care treatment centre but are not captured. Recommended fasting times were updated relatively infrequently in patients' metabolic charts. Episodes of metabolic decompensation were identifiable but required an operational definition based on acute manifestations most commonly recorded in the metabolic chart. Deaths occurred rarely in these patients and quality of mortality data was not evaluated.

CONCLUSIONS

Opportunities to record core outcomes at the metabolic clinic occur at least annually for children with MCAD deficiency. Methods to comprehensively capture emergency care received at outside institutions are needed. To reduce substantial heterogeneous recording of core outcome across treatment centres, improved documentation standards are required for recording of recommended fasting times and a consensus definition for metabolic decompensations needs to be developed and implemented.

Body Composition Evaluation and Clinical Markers of Cardiometabolic Risk in Patients with Phenylketonuria

Cardiovascular diseases are the main cause of mortality worldwide. Patients with phenylketonuria (PKU) may be at increased cardiovascular risk. This review provides an overview of clinical and metabolic cardiovascular risk factors, explores the connections between body composition (including fat mass and ectopic fat) and cardiovascular risk, and examines various methods for evaluating body composition. It particularly focuses on nutritional ultrasound, given its emerging availability and practical utility in clinical settings. Possible causes of increased cardiometabolic risk in PKU are also explored, including an increased intake of carbohydrates, chronic exposure to amino acids, and characteristics of microbiota. It is important to evaluate cardiovascular risk factors and body composition in patients with PKU. We suggest systematic monitoring of body composition to develop nutritional management and hydration strategies to optimize performance within the limits of nutritional therapy.

Heterogeneity and Gaps in Reporting Primary Outcomes From Neonatal Trials

OBJECTIVES

Clear outcome reporting in clinical trials facilitates accurate interpretation and application of findings and improves evidence-informed decision-making. Standardized core outcomes for reporting neonatal trials have been developed, but little is known about how primary outcomes are reported in neonatal trials. Our aim was to identify strengths and weaknesses of primary outcome reporting in recent neonatal trials.

METHODS

Neonatal trials including ≥100 participants/arm published between 2015 and 2020 with at least 1 primary outcome from a neonatal core outcome set were eligible. Raters recruited from Cochrane Neonatal were trained to evaluate the trials' primary outcome reporting completeness using relevant items from Consolidated Standards of Reporting Trials 2010 and Consolidated Standards of Reporting Trials-Outcomes 2022 pertaining to the reporting of the definition, selection, measurement, analysis, and interpretation of primary trial outcomes. All trial reports were assessed by 3 raters. Assessments and discrepancies between raters were analyzed.

RESULTS

Outcome-reporting evaluations were completed for 36 included neonatal trials by 39 raters. Levels of outcome reporting completeness were highly variable. All trials fully reported the primary outcome measurement domain, statistical methods used to compare treatment groups, and participant flow. Yet, only 28% of trials fully reported on minimal important difference, 24% on outcome data missingness, 66% on blinding of the outcome assessor, and 42% on handling of outcome multiplicity.

CONCLUSIONS

Primary outcome reporting in neonatal trials often lacks key information needed for interpretability of results, knowledge synthesis, and evidence-informed decision-making in neonatology. Use of existing outcome-reporting guidelines by trialists, journals, and peer reviewers will enhance transparent reporting of neonatal trials.

Paper I: Heterogeneous use of registry data for participant identification and primary outcome ascertainment is found in registry-based randomized controlled trials: A scoping review

OBJECTIVES

Registry-based randomized controlled trials (RRCTs) have potential to address limitations of traditional clinical trials. To describe their current use, information on planned and published RRCTs was identified and synthesized.

STUDY DESIGN AND SETTING

A scoping review of published RRCT protocols and reports was conducted. Articles published between 2010 and 2021 identified from electronic database searching, a recent review of RRCTs, and targeted searching for recent RRCT protocols (2018-2021) were screened. Data on trial data sources, types of primary outcomes, and how these primary outcomes were described, selected, and reported were extracted.

RESULTS

Ninety RRCT articles (77 reports; 13 protocols) were included. Forty nine (54%) used or planned to rely on registry data for their trial, 26 (29%) used both registry and additional data, and 15 (17%) used the registry solely for recruitment. Primary outcomes were routinely collected from the registry for 66 articles (73%). Only 28 articles (31%) described any methods to promote outcome data quality during or after data collection. Core outcome sets were not used in any of the trials.

CONCLUSION

With improvements in registry design, outcome selection, measurement, and reporting, future RRCTs may deliver on promises of efficient, high-quality trials that address clinically relevant questions.

Medium-chain Acyl-COA dehydrogenase deficiency: Pathogenesis, diagnosis, and treatment

INTRODUCTION

Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCADD) is the most common inherited metabolic disorder of β-oxidation. Patients with MCADD present with hypoketotic hypoglycemia, which may quickly progress to lethargy, coma, and death. Prognosis for MCADD patients is highly promising once a diagnosis has been established, though management strategies may vary depending on the severity of illness and the presence of comorbidities.

METHODS AND RESULTS

Given the rapid developments in the world of gene therapy and implementation of newborn screening for inherited metabolic disorders, the provision of concise and contemporary knowledge of MCADD is essential for clinicians to effectively manage patients. Thus, this review aims to consolidate current information for physicians on the pathogenesis, diagnostic tools, and treatment options for MCADD patients.

CONCLUSION

MCADD is a commonly inherited metabolic disease with serious implications for health outcomes, particularly in children, that may be successfully managed with proper intervention.

Newborn screening and genetic variation of medium chain acyl-CoA dehydrogenase deficiency in the Chinese population

OBJECTIVES

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an autosomal recessive disorder of the fatty acid oxidative metabolism. This study aimed to investigate the epidemiological characteristics, the spectrum of variation, clinical phenotype, and prognosis of MCADD in Chinese newborns.

METHODS

We retrospectively analysed newborn screening (NBS) data in the Zibo area from January 2016 to March 2022 and summarized 42 cases recently reported in Chinese neonates. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and next-generation sequencing (NGS) were used to detect the concentrations of carnitine in the blood spots and for diagnosis.

RESULTS

A total of 183,082 newborns were detected, and six patients were diagnosed with MCADD (1/3,0514). The primary octanoylcarnitine (C8) and the octanoylcarnitine/decanoylcarnitine ratio (C8/C10) were elevated in all patients. Gene analysis revealed four known and four novel variants of the ACADM gene. Five patients were asymptomatic and developed normally under dietary guidance. One child died of vaccination-induced MCADD, presenting with hypoglycemia and elevated acylcarnitines.

CONCLUSIONS

The incidence of MCADD in Chinese newborns varies geographically from 1/222,903 to 1/30,514, and the most common pathogenic variant is c.449_452 del CTGA (p. T150Rfs∗4) in ACADM gene with a frequency of 27.7%. HPLC-MS/MS and genetic analysis are beneficial for early prevention and good prognosis of MCADD.

Target Diseases for Neonatal Screening in Germany

BACKGROUND

Neonatal screening in Germany currently comprises 19 congenital diseases, 13 of which are metabolic diseases. Approximately one in 1300 newborns suffers from one of these target diseases. Early diagnosis and treatment enable the affected children to undergo better development and even, in many cases, to have a normal life.

METHODS

This review is based on pertinent publications retrieved by a selective search in the PubMed and Embase databases.

RESULTS

Positive screening findings are confirmed in approximately one out of five newborns. The prompt evaluation of suspected diagnoses is essential, as treatment for some of these diseases must be initiated immediately after birth to prevent longterm sequelae. The most commonly identified diseases are primary hypothyroidism (1:3338), phenylketonuria/hyperphenylalaninemia (1 : 5262), cystic fibrosis (1 : 5400), and medium-chain acyl-CoA dehydrogenase deficiency (1 : 10 086). Patient numbers are rising as new variants of the target diseases are being identified, and treatments must be adapted to their heterogeneous manifestations. Precise diagnosis and the planning of treatment, which is generally lifelong, are best carried out in a specialized center.

CONCLUSION

Improved diagnosis and treatment now prolong the lives of many patients with congenital diseases. The provision of appropriate long-term treatment extending into adulthood will be a central structural task for screening medicine in the future.

Patient and family engagement in the development of core outcome sets for two rare chronic diseases in children

BACKGROUND

Core outcome sets (COS) are lists of consensus-determined outcomes to be measured and reported in all clinical research studies within a disease area. While including patients and families in COS development to improve their relevance and applicability to patient values is key, there is limited literature documenting practical barriers and facilitators to successful patient engagement in COS development. In this paper, as researchers and patient partners, we provide a resource for COS developers to meaningfully and effectively engage patients and families.

MAIN BODY

To establish a consensus-based COS for children with two inherited metabolic diseases (medium-chain acyl-CoA dehydrogenase deficiency and phenylketonuria), we conducted an evidence review, Delphi survey, and workshop. Two adult patient partner co-investigators co-developed the study protocol, co-designed strategies to address challenges with incorporating patient perspectives, and led all patient engagement activities, including communication with a group of family advisors. Seven adult family advisors received training about COS development and subsequently contributed to Delphi survey development, outcome definitions, the consensus workshop, and selection of outcome measurement instruments. Patient partner co-investigators and family advisors were essential to the successful design, conduct, and completion of the two COS. Patient partner co-investigators supported the understanding, inclusion and engagement of family advisors, and helped develop accessible tools to determine patient-oriented outcome measurement instruments. Patient partner co-investigators and family advisors collaborated with the study team to co-develop surveys, modify technical language, and recruit participants to the study. Together, we addressed challenges to patient engagement in COS development such as unfamiliarity with study methods, comprehensibility of materials and ongoing engagement, and power imbalances between team members.

CONCLUSION

Our approach to patient and family engagement in COS development for two rare conditions for children was feasible and considered valuable by all study team members, including patients and family members, in improving the relevance of the deliverable to patients. This approach to patient engagement in developing COS can be applied to other paediatric disease contexts, allowing patient and family perspectives to influence the direction of future studies to develop COS.

Core Outcome Sets for Medium-Chain Acyl-CoA Dehydrogenase Deficiency and Phenylketonuria

BACKGROUND

Evidence to guide treatment of pediatric medium-chain acyl-coenzyme A dehydrogenase (MCAD) deficiency and phenylketonuria (PKU) is fragmented because of large variability in outcome selection and measurement. Our goal was to develop core outcome sets (COSs) for these diseases to facilitate meaningful future evidence generation and enhance the capacity to compare and synthesize findings across studies.

METHODS

Parents and/or caregivers, health professionals, and health policy advisors completed a Delphi survey and participated in a consensus workshop to select core outcomes from candidate lists of outcomes for MCAD deficiency and PKU. Delphi participants rated the importance of outcomes on a nine-point scale (1-3: not important, 4-6: important but not critical, 7-9: critical). Candidate outcomes were progressively narrowed down over 3 survey rounds. At the workshop, participants evaluated the remaining candidate outcomes using an adapted nominal technique, open discussion, and voting. After the workshop, we finalized the COSs and recommended measurement instruments for each outcome.

RESULTS

There were 85, 61, and 53 participants across 3 Delphi rounds, respectively. The candidate core outcome lists were narrowed down to 20 outcomes per disease to be discussed at the consensus workshop. Voting by 18 workshop participants led to COSs composed of 8 and 9 outcomes for MCAD deficiency and PKU, respectively, with measurement recommendations.

CONCLUSIONS

These are the first known pediatric COSs for MCAD deficiency and PKU. Adoption in future studies will help to ensure best use of limited research resources to ultimately improve care for children with these rare diseases.

Developments in evidence creation for treatments of inborn errors of metabolism

Inborn errors of metabolism (IEM) represent the first group of genetic disorders, amenable to causal therapies. In addition to traditional medical diet and cofactor treatments, new treatment strategies such as enzyme replacement and small molecule therapies, solid organ transplantation, and cell-and gene-based therapies have become available. Inherent to the rare nature of the single conditions, generating high-quality evidence for these treatments in clinical trials and under real-world conditions has been challenging. Guidelines developed with standardized methodologies have contributed to improve the practice of care and long-term clinical outcomes. Adaptive trial designs allow for changes in sample size, group allocation and trial duration as the trial proceeds. n-of-1 studies may be used in small sample sized when participants are clinically heterogeneous. Multicenter observational and registry-based clinical trials are promoted via international research networks. Core outcome and standard data element sets will enhance comparative analysis of clinical trials and observational studies. Patient-centered outcome-research as well as patient-led research initiatives will further accelerate the development of therapies for IEM.

The Impact of a Slow-Release Large Neutral Amino Acids Supplement on Treatment Adherence in Adult Patients with Phenylketonuria

The gold standard treatment for phenylketonuria (PKU) is a lifelong low-phenylalanine (Phe) diet supplemented with Phe-free protein substitutes. Adherence to therapy becomes difficult after childhood. Supplementing with large neutral amino acids (LNAAs) has been proposed as an alternative medication to Phe-free protein substitutes (i.e., amino acid mixtures). The aim of this study was to evaluate adherence to therapy and quality of life (QoL) in a cohort of sub-optimally controlled adult PKU patients treated with a new LNAA formulation. Twelve patients were enrolled in a 12-month-trial of slow-release LNAAs (1g/kg/day) plus a Phe-restricted diet. Medication adherence was measured with the Morisky Green Levine Medication Adherence Scale; the QoL was measured using the phenylketonuria-quality of life (PKU-QoL) questionnaire. Phe, tyrosine (Tyr) levels, and Phe/Tyr ratios were measured fortnightly. Before treatment, 3/12 patients self-reported a ‘medium’ adherence to medication and 9/12 reported a low adherence; 60% of patients reported a full adherence over the past four weeks. After 12 months of LNAA treatment, all patients self-reported a high adherence to medication, with 96% reporting a full adherence. Phe levels remained unchanged, while Tyr levels increased in most patients. The Phy/Tyr ratio decreased. All patients had a significant improvement in the QoL. LNAAs may give patients a further opportunity to improve medication adherence and, consequently, their QoL.