Principles and performance: assessing the evidence

International differences in the evaluation of conditions for newborn bloodspot screening: a review of scientific literature and policy documents

Despite international adoption of newborn bloodspot screening (DBS), no two countries' screening programs are the same. This article aims to understand what factors influence DBS decision-making criteria and how conditions are assessed against them. In doing so, it offers unique insights into the international landscape of DBS. A systematic review on DBS criteria in scientific literature was first undertaken. Through this, five topics were identified for consideration when analyzing DBS decision-making. Using these five topics as a template, a side-by-side comparison was conducted on DBS in policy documents of eight countries. Programs are using different approaches to explore the same policy issues, including: the beneficiary of DBS, definition of criteria, the way conditions are assessed, level of evidence required, and recommendations after assessment. These differences have the potential to result in increased disparity across DBS internationally. Ultimately, governments need to decide on their role and develop an approach to DBS decision-making in line with this role. The analyses presented in this article highlight that despite programs' commonalities, no one 'DBS decision-making solution' exists. Understanding the different approaches to decision-making within the literature and policy settings, provides an objective starting point for structured decision-making approaches for DBS programs.

Screening for conditions that do not meet the Wilson and Jungner criteria: the case of Duchenne muscular dystrophy

In this manuscript, I examine four overlapping policy and ethical issues regarding screening newborns (and infants) for Duchenne muscular dystrophy (DMD). First, what are the risks and benefits of expanding newborn screening (NBS) to include DMD? Second, if NBS were to expand to include DMD, should it require informed consent? Third, should NBS for DMD be limited to boys? Why or why not? Fourth, when is the ideal timing for screening (prenatal, newborn, or later in infancy) and what factors influence this determination? I argue that decisions about when, how, and whom to test reflect a tension between maximizing uptake and diagnosis versus maximizing autonomy and choice with respect to genetic information. I conclude that screening for DMD is a valid moral option, but not as part of the mandatory NBS population program. Rather, I propose that screening for DMD should be offered only on a voluntary basis beyond the newborn period. I support offering this screening to families of young boys and girls to ensure that all children and their families can benefit from early diagnosis and its reproductive implications. A rigorous consent process will be necessary to ensure that the decision whether or not to test is a voluntary and informed choice.

Newborn bloodspot screening in the UK – past, present and future

Screening newborn babies for inherited metabolic disease began in the UK in the late 1950s with the ‘nappy test’ for phenylketonuria. In 1969 the Department of Health recommended changing to bloodspot screening using the techniques developed in the USA by Robert Guthrie and his associates. Bloodspot screening for various other disorders (galactosaemia, maple syrup urine disease, homocystinuria, cystic fibrosis and others) was introduced on a patchy local basis but, until 2000, the only additional disorder officially recommended was congenital hypothyroidism. Screening for haemoglobinopathies received official support in 2000 and for cystic fibrosis in 2001 though implementation was slow, particularly for the latter. Both these screens have raised difficult issues relating to genetic privacy and the detection of carrier status in children. During the last decade screening has become increasingly subject to central control. Though a more consistent and systematic approach was clearly needed, this has undoubtedly slowed the rate of innovation. In particular the UK has lagged behind many other European countries in the application of tandem mass spectrometry (MS-MS) though, following a major pilot study, screening for medium-chain acyl-CoA dehydrogenase deficiency is now in the process of introduction. Attempts to codify clinical and laboratory procedures have also proved controversial, highlighting marked differences in practice in various parts of the country and the difficulty of rationalizing these within a practicable and scientifically justified framework. Notwithstanding this, there are many positive developments and newborn screening remains a stimulating and rewarding field in which to work.

Introducing new screens: why are we all doing different things?

The disease panels covered by newborn blood spot screening vary greatly from country to country. There are different interpretations of the Wilson and Jungner principles and of underlying data in the scientific literature, and great disparities between the value judgements applied in screening and in routine clinical practice.

Neonatal biochemical screening for disease

BACKGROUND

The practice of screening the neonatal population for certain diseases by biochemical testing of a dried blood spot is an established public health initiative in many countries. The diseases for which screening is done vary from region to region, based on ethnic, financial and political considerations. Criteria have been established to identify diseases suitable for neonatal screening.

DISEASES SCREENED

In Western countries, screening for phenylketonuria (PKU) and congenital hypothyroidism (CH) has been introduced throughout. Subsequently, cost-benefit analysis has confirmed the existence of a financial benefit. Other diseases screened for in some regions include galactosemia, aminoacidemias and organic acidemias, cystic fibrosis, congenital adrenal hyperplasia, biotinidase deficiency, hemoglobinopathies, glucose-6-phosphate dehydrogenase deficiency, and Duchenne muscular dystrophy, although in no case has a clear financial benefit been established.

CONCLUSIONS

Since the introduction of neonatal screening over 40 years ago, new methods have resulted in an increase in the number of diseases amenable to screening, better automation and greater specificity. Methods currently used include growth of an inhibited bacterial auxotroph (the original phenylalanine (phe) method of Dr. Robert Guthrie), spectrophotometry, fluorometry, immunoassay, and tandem mass spectrometry with electrospray ionization.

Neonatal screening for metabolic, endocrine, infectious, and genetic disorders. Current and future directions

There are good reasons to expect that future neonatal screening will expand both to include more disorders and to cover more of the global newborn population. Disorders for which neonatal screening will be given high priority in the health care field in the future are CH and PKU. Screening for CH is likely to expand faster than screening for PKU, especially in the developing world. In the future, screening for CAH will be practiced much more widely than today. Screening for CF is likely to qualify for routine neonatal screening in the future, especially if gene therapy becomes successful. Screening for infectious diseases is an area that is also developing rapidly. Which disorders to screen for neonatally will depend on a number of factors that are unique to each society, such as the prevalence, economy, and ethics. This must be realized when international guidelines are drafted. Technical development, which is of major importance for neonatal screening, includes MS-MS, different DNA techniques, and automation. The expansion of biomedical knowledge in a wide variety of fields will establish new grounds for neonatal screening.