June 13, 2024
Newborn screening (NBS) is a critical healthcare initiative conducted shortly after birth to detect serious inherited developmental and metabolic disorders that are treatable. This proactive approach allows for pre-symptomatic detection and intervention, preventing irreversible complications such as mental retardation, long-term physical disabilities, or even premature death.Essentially, newborn screening identifies and addresses potential health issues in babies before they become ill.
Universal newborn screening began in the United States in the mid-1960s when Dr Robert Guthrie pioneered the first screening test for Phenylketonuria (PKU). By the mid-1990s, the introduction of tandem mass spectrometry (TMS) expanded the range of disorders that could be detected from dried blood spots. Today, nearly all newborns in the US are screened for about 62 disorders, including both core and secondary conditions, as recommended by the Uniform Screening Panel (RUSP).
Globally, 40 million babies are screened annually, representing about 28% of infants born each year. Most countries now adhere to the RUSP recommended list, which includes a variety of metabolic disorders. Inherited Errors of Metabolism (IEMs), often life-threatening, typically manifest after an initial period of apparent good health, ranging from hours to weeks following an uncomplicated pregnancy and full-term birth. Preliminary symptoms can be non-specific, such as weight loss, growth challenges, seizures, and unusual odours in sweat or urine, leading to missed diagnoses. IEMs result from enzyme defects in biochemical and metabolic pathways, affecting the breakdown of proteins, fats, and carbohydrates, and causing toxic build-up.
Metabolic disorders that are tested can be grouped into categories such as organic acid, fatty acid, amino acid and carbohydrate disorders, glycogen storage disease, and lysosomal storage disorders. While individual IEMs are rare, they are collectively common with an overall incidence greater than 1 in 1,000 births. Other disorders screened for include hearing impairment, critical congenital heart disease, Congenital Adrenal Hyperplasia, Congenital Hypothyroidism, thalassemia, cystic fibrosis, and Severe Combined ImmunoDeficiency (SCID).
Newborn screening uses noninvasive hearing tests, pulse oximetry for critical congenital heart disease, and blood spot tests analysed by Tandem Mass Spectrometry, fluorometry, and immunoassays. A heel-prick is used to collect the baby’s blood on special filter paper and screenings are conducted 24-48 hours after birth, ensuring accurate results after the baby has received breast milk or formula.
Pilot studies in several countries are exploring the integration of genetic sequencing to expand the screening panel to 400 genetic disorders. The goal is to create a multi-tier approach using both biochemical and genetic tests to improve accuracy and reduce false positives and missed cases.
In India, dried blood spot screening benefits are increasingly recognised, yet a cohesive national strategy for implementing a universal NBS programme is lacking. There is no clear guidance on which prevalent disorders should be included in the screening panel. Regions such as Chandigarh, Kerala, and Goa have initiated NBS programmes in govt hospitals, screening for about eight genetic disorders. Kerala’s ‘Shalabham’ programme, launched in 2018, screens 150,000 newborns a year in 90 hospitals. In states without govt-sponsored initiatives, a few leading children’s hospitals conduct extended newborn screenings through private NBS laboratories.
India, with nearly 28 million births annually, accounts for one-fifth of the world’s childbirths. Tamil Nadu, a relatively developed state with a low birth rate, sees more than 1.1 million live births yearly. Reports indicate that 13 of 100 babies born in 2021-2022 were under the recommended birth weight, signaling potential metabolic illness or mortality risks. Notably, since the inception of the National Health Mission (NHM) in 2005, Tamil Nadu’s infant mortality rate has declined from 37 in 2005 to 8.5 in 2023, which is exceptionally lower than the national average. However, premature death or mortality alone does not fully capture the burden of disease borne by different populations.
The overall burden of disease is assessed using the disability-adjusted life year (DALY), representing the loss of one year of full health. DALYs for a disease or health condition are the sum of years of life lost due to premature mortality and years of healthy life lost due to disability. The leading cause of DALYs globally is neonatal conditions and birth defects, which is several-fold higher than measles, tuberculosis, and respiratory infections. A March report from WHO mentions that the South Asia region witnessed improvement in under-five mortality, but the contribution of birth defects has increased from 4% to 11% in the past two decades. Universal newborn screening in India can significantly reduce DALYs by enabling early treatment and accurate management, thereby improving long-term health outcomes.
Implementing universal NBS in Tamil Nadu presents significant benefits and considerable challenges. The estimated annual cost for the small programme is about `80 crore with a significant benefit-to-cost ratio (1.8 to 6). The economic benefits of preventing intellectual disabilities and reducing DALY scores far outweigh the costs of screening, surveillance, and management.
Challenges include operational management, sample delivery delays, and increased lab rejections of blood spot samples. Addressing these would include establishing a primary screening lab centre equipped with advanced mass spectrometry and genetic sequencing and developing an efficient sample delivery system to mail blood cards from hospitals to screening labs. Additionally, creating a notification system to alert primary care physicians and parents about positive results and setting up certified diagnostic labs for accurate confirmatory tests.
Many developing countries, including the Philippines, have successfully implemented universal screening programmes, demonstrating that it is feasible and beneficial. Tamil Nadu should consider a phased or universal screening programme for all newborns, and perhaps serve as a model for the rest of India.
(The writer is a clinical biochemical genetics fellow at the Children’s Hospital of Philadelphia)
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