Expanded newborn screening: Lessons learned from MCAD deficiency

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.

Newborn Screening of Primary Carnitine Deficiency: An Overview of Worldwide Practices and Pitfalls to Define an Algorithm before Expansion of Newborn Screening in France

Primary Carnitine Deficiency (PCD) is a fatty acid oxidation disorder that will be included in the expansion of the French newborn screening (NBS) program at the beginning of 2023. This disease is of high complexity to screen, due to its pathophysiology and wide clinical spectrum. To date, few countries screen newborns for PCD and struggle with high false positive rates. Some have even removed PCD from their screening programs. To understand the risks and pitfalls of implementing PCD to the newborn screening program, we reviewed and analyzed the literature to identify hurdles and benefits from the experiences of countries already screening this inborn error of metabolism. In this study, we therefore, present the main pitfalls encountered and a worldwide overview of current practices in PCD newborn screening. In addition, we address the optimized screening algorithm that has been determined in France for the implementation of this new condition.

Trends in Scottish newborn screening programme for congenital hypothyroidism 1980-2014: strategies for reducing age at notification after initial and repeat sampling

OBJECTIVES

To determine ages at first capillary sampling and notification and age at notification after second sampling in Scottish newborns referred with elevated thyroid-stimulating hormone (TSH).

SUBJECTS AND METHODS

Referrals between 1980 and 2014 inclusive were grouped into seven 5-year blocks and analysed according to agreed standards.

RESULTS

Of 2 116 132 newborn infants screened, 919 were referred with capillary TSH elevation ≥8 mU/L of whom 624 had definite (606) or probable (18) congenital hypothyroidism. Median age at first sampling fell from 7 to 5 days between 1980 and 2014 (standard 4-7 days), with 22, 8 and 3 infants sampled >7 days during 2000-2004, 2005-2009 and 2010-2014. Median age at notification was consistently ≤14 days, range falling during 2000-2004, 2005-2009 and 2010-2014 from 6 to 78, 7-52 and 7-32 days with 12 (14.6%), 6 (5.6%) and 5 (4.3%) infants notified >14 days. However 18/123 (14.6%) of infants undergoing second sampling from 2000 onwards breached the ≤26-day standard for notification. By 2010-2014, the 91 infants with confirmed congenital hypothyroidism had shown favourable median age at first sample (5 days) with start of treatment (10.5 days) approaching age at notification.

CONCLUSION

Most standards for newborn thyroid screening are being met by the Scottish programme, but there is a need to reduce age range at notification, particularly following second sampling. Strategies to improve screening performance include carrying out initial capillary sampling as close to 96 hours as possible; introducing 6-day laboratory reporting and use of electronic transmission for communicating repeat requests.

Morbidity and mortality among exclusively breastfed neonates with medium-chain acyl-CoA dehydrogenase deficiency

PURPOSE

Despite greatly improved morbidity and mortality among infants with medium-chain acyl-CoA dehydrogenase deficiency (MCAD) since the implementation of universal newborn screening (NBS), a population of neonates still becomes ill before their positive screen results are available. Exclusive breastfeeding is a proposed risk factor in this group. Since initial studies of MCAD NBS, breastfeeding rates have increased substantially. In this study, we quantify the current risk of early decompensation in neonates with MCAD and identify factors associated with poor outcomes.

METHODS

We completed a retrospective analysis of neonates with MCAD referred to our center between 2010 and 2015.

RESULTS

Of 46 infants with MCAD, 11 (23.9%) were symptomatic before the return of the NBS results. Four died or had cardiac arrest; the remaining seven had lethargy and hypoglycemia. All symptomatic patients were exclusively breastfed; only 40.6% of asymptomatic patients were exclusively breastfed. Breastfeeding rates increased from 45.5% in 2010-2011 to 64.7% in 2012-2013 and 87.5% in 2014-2015. Over these same periods, rates of early decompensation increased from 9.09% to 23.5% and 75%, respectively.

CONCLUSIONS

Exclusively breastfed neonates with MCAD are at risk for early metabolic decompensation. As breastfeeding rates increase, close management of feeding difficulties is essential for all neonates awaiting NBS results.Genet Med 18 12, 1315-1319.

Incidence of medium-chain acyl-CoA dehydrogenase deficiency in Canada using the Canadian Paediatric Surveillance Program: Role of newborn screening

BACKGROUND

The incidence of medium-chain acyl-CoA dehydrogenase deficiency (MCADD) was estimated using the Canadian Paediatric Surveillance Program (CPSP) in Canada over a three-year period. Data regarding mutations associated with MCADD cases were collected wherever available.

METHODS

Data were collected over a 36-month period using a monthly mailed questionnaire distributed through the CPSP to more than 2500 Canadian paediatricians, medical geneticists and paediatric pathologists.

RESULTS AND CONCLUSIONS

During the three years of MCADD surveillance, 46 confirmed cases out of a total of 71 reported cases were found - an average of approximately 15 cases per year. This rate is lower than the initial estimate of approximately 30 cases per year of MCADD in Canada, based on the reported incidence of MCADD in the literature of approximately one in 10,000 to one in 20,000. All cases ascertained by newborn screening were asymptomatic. There were two deaths, both in jurisdictions without newborn screening for MCADD. The data support population-based newborn screening for MCADD.

Newborn screening in Canada - Are we out of step?

OBJECTIVES

To review the status of universal newborn screening programs in Canada.

METHODS

A brief questionnaire (seven questions) was circulated to one key individual in each province (n=10) and territory (n=3). These individuals were usually physicians or clinical biochemists closely involved in the diagnosis and treatment of genetic metabolic diseases.

RESULTS

Universal newborn screening is under provincial jurisdiction. The number of diseases screened for varies and ranges from three to 28. Nine provinces/territories have a central computerized system for tracking initially positive cases. Only five provinces/territories have adequate personnel and resources for follow-up and treatment. Treatment costs are only partially covered in most jurisdictions. Only five provinces/territories have formal advisory committees with official mandates. Expensive, restricted access treatment products for adults with inherited metabolic diseases are only fully available in six provinces/territories. There is very limited access to these products in an additional four provinces/territories. To date, specific informed consent for newborn screening is not required in any province or territory.

CONCLUSIONS

Canada is far behind the rest of the developed (and some 'emerging') countries of the world in the field of universal newborn screening. New strategies for advocating expanded screening, follow-up and (long-term) payment of treatment costs on behalf of the potentially affected infants and their families must be devised, and such initiatives should include participation from the new Public Health Agency of Canada.