Economic Evaluation of newborn screening for severe combined immunodeficiency and spinal muscular atrophy
Severe combined immunodeficiency (SCID) is a group of rare inherited immune deficiencies characterized by a severe deficiency of T-cells. Without treatment, babies usually succumb to overwhelming infection in the first two years of life. Over the last decade, early treatment with haematopoietic stem cell transplantation (HSCT) has significantly altered the trajectory of these children with almost complete survival if performed before 3.5 months of age.
Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disease resulting in degeneration of motor neurons in the spinal cord and brainstem, progressive muscle weakness and atrophy and significant disability. It continues to represent the leading genetic cause of infant death due to respiratory insufficiency, with a pan–ethnic incidence of approximately one in 11,000 live births. Historically SMA has been an incurable disease, however, over the last decade, new disease-modifying treatments have changed disease trajectories with the most impressive results seen if treatment is initiated in the presymptomatic phase of the disease.
Importantly, the benefits of early diagnosis and initiation of treatment are now increasingly recognized for both SMA and SCID, with the most beneficial response to treatment to date in these disorders, seen in patients treated prior to the onset of symptoms.
The Sydney Children’s Hospital Network (SCHN) performed a state-wide (NSW/ACT) newborn screening (NBS) research pilot from August 2018 to August 2020 to screen for SMA and primary immunodeficiency (PID), specifically SCID and B-cell deficiency. In total, 202,388 newborns were screened.
The rationale for combining SCID and SMA in the NBS program is that dried blood spot NBS has been shown to be effective at identifying both these conditions presymptomatically, and the marginal cost of combining these diseases into a NBS panel is AUD $7 for screening one disorder and only an additional $1 for two disorders.
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Over the 60-year time horizon, screening every newborn in the population and treating diagnosed SMA infants with gene therapy is assumed to achieve the same health gain but at a much lower total cost ($328 vs. $1,063 per newborn in the population).
Compared to late nusinersen treatment in clinically diagnosed SMA patients (primary comparator), NBS and early gene therapy would be more effective (0.00095 QALYs gained) and less costly ($190 cost savings) than no screening and late treatment with nusinersen in symptomatic SMA patients, that is, gene therapy was dominant from a cost-effectiveness standpoint.
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Research team
- Sophy TF Shih
- Michelle A Farrar
- Veronica Wiley
- Melanie Wong
- Elena Keller
- Georgina M Chambers
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- The Children’s Hospital Network (at Westmead), Sydney Children’s Hospitals Network
- UNSW Sydney