Trends in the Timeliness of Spinal Muscular Atrophy Detection in US Infants, 2016–2023
by
, ,
Scott D. Grosse
1,2,*
,
Kai Hong
3,
Golriz K. Yazdanpanah
1,
Ashley Nash
1,
Amy Gaviglio
1,4,
Marcus Gaffney
1,
Kendra A. K. Lawrence
5 and
Jennifer M. Kwon
6 1
Division of Laboratory Sciences, Newborn Screening and Molecular Biology Branch, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA
2
Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55545, USA
3
Office of Policy, Performance, and Evaluation, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
4
Association of Public Health Laboratories, Silver Spring, MD 20814, USA
5
Department of Pharmacotherapy, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, USA
6
Division of Pediatric Neurology, Department of Neurology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792, USA
*
Author to whom correspondence should be addressed.
Int. J. Neonatal Screen. 2026, 12(1), 9; https://doi.org/10.3390/ijns12010009
Submission received: 22 January 2026
/
Revised: 11 February 2026
/
Accepted: 13 February 2026
/
Published: 18 February 2026
Abstract
Screening for spinal muscular atrophy (SMA) was adopted by all US state newborn screening programs between 2018 and 2024; by the end of 2022, 48 states were screening for SMA. We assessed trends in health insurance records of SMA diagnoses to quantify improvements in the timeliness of SMA identification following the adoption of screening. We used nationally representative Medicaid claims data for approximately half of US births covered by public insurance and a convenience sample of employer-sponsored health plans. We analyzed records for birth cohorts with at least 1 full year of follow-up (i.e., through the end of the following calendar year). For 2017 births, 1.3 per 100,000 infants had SMA codes first recorded by 1 month of age; this increased to 6.6 per 100,000 among publicly insured newborns born in 2022. The rollout of SMA newborn screening across US states was also followed by improvements in the timely detection of SMA. The proportion of infants with SMA detected by 1 month increased from 18% in 2017 to 61% in 2021 and is projected to reach 75% in 2022. Growth in timely detection was even greater in the employer-insured sample. Timely diagnosis of SMA can enable the initiation of treatment prior to the irreversible loss of motor function.
1. Introduction
Over the past 25 years, implementation of newborn bloodspot screening (NBS) methods such as tandem mass spectrometry and the expansion of screening panels to include additional disorders have led to the timely identification and treatment of many thousands of newborns each year and have been highlighted as one of the leading public health successes of the early 21st century [1,2]. The screening pathway includes blood collection via a heel prick onto a blood spot specimen card, transport of the specimen to a laboratory, testing, reporting of results, diagnostic/confirmatory testing, and referral to a provider for treatment once a child is diagnosed. Because delays in this time-sensitive pathway can have adverse consequences for affected newborns, the United States (US) government has set a goal that presumptive positive NBS results for time-critical conditions, defined as conditions that may manifest with acute symptoms in the first days of life and require immediate treatment to reduce the risk of morbidity and mortality, be communicated to the newborn’s healthcare provider no later than 5 days of life [3,4].
One of these time-critical conditions is spinal muscular atrophy (SMA), a genetic disease affecting roughly 1 in 15,000 to 1 in 10,000 children that is caused by mutations in both copies of the survival motor neuron 1 (SMN1) gene. As an autosomal recessive disorder, SMA occurs on average in one-fourth of children born to a carrier couple; consequently, a minority of families may have more than one affected child. Reduced production of the SMN protein leads to progressive loss of motor neurons in the spinal cord. SMA type I generally results in death by the age of 2 years in the absence of treatment [5]. The number of copies of the SMN2 modifier gene, which produces small amounts of functional SMN protein, predicts disease phenotype [6].
Disease-modifying therapies introduced in the past decade include an intrathecal antisense oligonucleotide treatment, nusinersen (Spinraza®, Biogen, Cambridge, MA, USA), which was approved by the US Food and Drug Administration (FDA) in 2016. Two other medications were subsequently approved. An intravenous gene therapy using an adeno-associated virus serotype 9 (AAV9) vector, onasemnogene abeparvovec or OA (Zolgensma®, Novartis Gene Therapies, Bannockburn, IL, USA), was approved by the FDA in 2019 for children < 2 years of age, and an oral antisense oligonucleotide, risdiplam (Evrysdi®, Genentech, South San Francisco, CA, USA), was approved by the FDA in 2020 for US patients of all ages [7]. NBS for SMA was added to the US Recommended Uniform Screening Panel (RUSP) in 2018 on the basis of preliminary evidence of short-term improvements in outcomes with early initiation of treatment (within 6 weeks of birth) with nusinersen [8]. Subsequently, published evidence demonstrated that nusinersen administered to infants significantly improved survival and motor function in infants with 2 or 3 SMN2 copies [7,9,10]. Immediate treatment for infants with 4 SMN2 copies has also been recommended by a working group of clinicians and geneticists convened by Cure SMA [11].
Screening for SMA is conducted by amplification of DNA using real-time polymerase chain reaction (RT-PCR) assays to identify individuals with homozygous loss of SMN1 exon 7, which accounts for roughly 95% of SMA cases [12]. In most US programs, the SMA assay is multiplexed with a PCR-based assay used to screen for SCID and T-cell lymphopenias. The ability to conduct multiplex screening for SMA with SCID, for which all states were screening by 2018, reduced the need for additional instrumentation, reagents, and staff time and enabled the rapid adoption of SMA screening by US NBS programs [13,14]. The multiplexing of SMA and SCID testing has also been reported to be more cost-effective [15].
One US state, Utah, began screening all newborns for SMA in January 2018 [16]. Almost all states had begun screening for SMA by the end of 2022, with the last state beginning screening in early 2024 (Table 1). The pace of adoption of SMA following its addition to the RUSP was rapid relative to that of other conditions added to the RUSP [14,17]. Implementation of SMA NBS in other countries has also grown rapidly since 2021 [18,19].
Based on pooled NBS program data from 30 states for infants born during 2018–2022, 425 (1 in 14,694 births, or 6.8 per 100,000 births) had a confirmed SMA diagnosis [20]. Another analysis of data pooled from 22 states reported a birth prevalence of 1 in 13,862 births, or 7.2 per 100,000 births [21].
2. Materials and Methods
We accessed two independent proprietary healthcare administrative databases: Merative™ (Ann Arbor, MI, USA) MarketScan® Commercial data and Centers for Medicare & Medicaid Services (CMS) Medicaid data. Both are closed payer claims databases that record all healthcare encounters billed to participating payers for individuals enrolled in participating plans during the specified time periods. They include records for outpatient and inpatient services and filled outpatient pharmacy prescriptions, with associated diagnosis and procedure codes. Encounters not billed to data contributors are not included (see the Limitations section in the Discussion). Available demographic information for both databases includes age (in years) and sex.
The MarketScan Commercial databases contain person-level, deidentified administrative claims and encounters for privately insured employees and covered family members enrolled in participating employer-sponsored health insurance plans throughout the US. More than 250 self-insured employers and other health plans contributed data for approximately 65 million unique enrollees from 2017 to 2024. Annual numbers of enrollees included in the MarketScan Commercial data decreased over time as a result of changes in contracting arrangements. The Centers for Disease Control and Prevention (CDC) licenses the MarketScan research databases and software for approved public health activities conducted by CDC researchers. MarketScan data were accessed and extracted by the first author (S.D.G.) using Merative MarketScan Treatment Pathways, an online analytic platform that includes data from participating health plans reporting outpatient pharmacy records for their enrollees. Data tabulations were prepared using Microsoft Excel (Redmond, WA, USA).
Medicaid data from CMS contain person-level, deidentified administrative claims and encounters for publicly insured children and adults. The CMS Medicaid data include records for individuals enrolled in Medicaid and Children’s Health Insurance Program (CHIP) plans that contributed data. Records for more than 25 million unique enrollees of all ages from 2017 to 2023 were accessed by the second author (K.H.) through a unique CDC–CMS data use agreement that provides access to selected CDC researchers for approved projects. The Medicaid data include records for more than half of all US births during these years. Data tabulations were prepared using Microsoft Excel.
We created calendar-year birth cohorts for both the Commercial and Medicaid databases. Identification of birth cohorts in the CMS Medicaid data was based on recorded dates of birth. Because the MarketScan research databases do not list dates of birth, we used diagnosis and procedure codes, age in years, and inpatient place-of-service codes to identify presumed birth hospitalizations in the MarketScan Commercial analysis. More than 98% of US infants are born in hospitals [22].
Administratively reported International Classification of Diseases, 10th Revisions (ICD-10) diagnosis codes for infantile SMA, type I (G12.0), other specified SMA (G12.1, G12.8), or unspecified SMA (G12.9) were used to identify potential SMA cases. Our administrative case definition of presumptive SMA diagnoses involved an algorithm requiring the presence of an SMA diagnosis code on 1 or more inpatient claims or 3 or more outpatient claims at least 6 days apart, recorded within the first 4 years of life or prior to disenrollment. Because the accuracy of diagnosis codes is higher for inpatient claims than for outpatient records, health services researchers typically require the presence of diagnosis codes in more than one outpatient claim [23]. For the same reason, previous analyses of healthcare administrative databases for SMA cases have required either 1 inpatient record or 2 or more outpatient claims or encounters with SMA diagnosis codes [24,25], 2 or more claims in any setting with SMA codes [26,27], or a minimum of 1 inpatient record or 3 or more outpatient records with SMA codes [28,29].
We assessed the administrative prevalence of SMA at specific timepoints by calculating the timing of the first SMA record for presumptive SMA cases relative to birth (Medicaid) or birth hospitalization (Commercial), recorded prior to 1, 3, 12, or 24 months. Our primary measure of timeliness of case detection was the percentage of all cases detected by the age of 24 months that had a first claim with an SMA diagnosis code recorded by 1 month of age. For the 2022 Medicaid and 2023 Commercial birth cohorts, which by definition could not have 24 months of follow-up data, we report the percentage of cases meeting the SMA case algorithm by 12 months of age that had a first SMA diagnosis code recorded by 12 months of age.
3. Results
3.1. CMS Medicaid Data
Table 1 shows the total number of presumed SMA cases by age in the Medicaid database and the corresponding numbers of live births for each birth cohort, which declined from 2.2 million in 2016 and 2017 to <2.0 million after 2019.
Table 2 shows the calculated administrative prevalence of presumed SMA cases at ages 1 to 24 months for each Medicaid birth cohort from 2016 to 2022, derived from the numbers reported in Table 1. The administrative birth prevalence (assessed at age 24 months) during 2017–2019 ranged from 6.5 to 6.9 per 100,000 births, which is similar to the roughly 7 per 100,000 birth prevalence reported in state program data [20,21]. The administrative birth prevalence was higher in the Medicaid 2020 and 2021 birth cohorts, ranging from 8.5 to 8.9 per 100,000 births.
The percentage of SMA cases recorded in Medicaid data by age 24 months that had been diagnosed by 1 month of age increased throughout the study period, from 13.5% in 2016 to 60.6% in 2021. The percentage of cases recorded by 12 months of age that had been detected by 1 month of age, a secondary measure of timing, further increased from 63.9% (101/158) in 2021 to 76.4% (133/174) in 2022.
3.2. MarketScan Commercial Data
Almost no SMA diagnosis codes at any age were recorded for the 2017 Commercial birth cohort (n = 3). The absolute numbers of presumed SMA cases meeting the case definition by age 48 months fluctuated in the Commercial birth cohorts from 2018 to 2021, ranging from 9 to 15 (Table 3).
Table 4 shows the administrative prevalence of SMA at ages 1, 3, 12, and 24 months for the 2018–2023 Commercial birth cohorts. The administrative prevalence of SMA in the Commercial birth cohorts by 24 months of age increased over time, from 6.1 per 100,000 in 2018 to 10.8 per 100,000 in 2023. The percentage of cases detected by 24 months of age that had SMA diagnosis codes recorded in the first month of life increased rapidly, from 9.1% in 2018 to 83.3% in 2022. In the 2023 birth cohort, 100% of infants with a diagnosis of SMA by 12 months of age had a diagnosis code recorded by 1 month, compared with 83.3% of the 2022 birth cohort using the same metric of timely detection.
4. Discussion
This is the first published report of nationwide trends in the detection of SMA among US infants assessed using two administrative health data sources. Our primary results are based on CMS Medicaid claims data, which comprise more than half of US births (3.9 million in 2017 and 3.7 million in 2022 [30]). In comparison, the MarketScan Commercial cohorts accounted for <5% of US births, and the precision and reliability of the estimates are subject to greater uncertainty owing to the small number of infants with SMA.
Implementation of SMA NBS in Utah was associated with detection in the first month of life for all infants with SMA born in Utah during the first 5 years of screening [16].
In the Medicaid database, timely detection (by 1 month) among cases detected by 24 months of age rose from 23.4% for the 2018 birth cohort to 60.6% for the 2022 birth cohort. Although the 2022 birth cohort did not have complete follow-up through 24 months of age, as the last records were for December 2023, the proportion of SMA cases detected by 12 months of age that had a first SMA diagnosis code recorded in the first month of life was 76.4%. In comparison, the proportion of infants in the MarketScan database with presumptive diagnoses detected by 24 months that had an SMA diagnosis code recorded by 1 month of age increased from 9.1% in the 2018 cohort to 83.3% in the 2022 cohort, all of whom potentially had follow-up data through 24 months of age. The higher percentage of SMA cases detected by 1 month in the 2022 privately insured cohort (83.3%) compared with the publicly insured cohort (60.6%) may reflect differential access, but the numbers were too small for robust inference.
Timely diagnosis of SMA supports presymptomatic initiation of disease-modifying therapies. The NURTURE study found that initiation of nusinersen between 3 and 42 days of age was associated with significantly improved outcomes for infants with 2 or 3 SMN2 copies relative to historical controls [10,31]. Outside of clinical trials, however, newborn screening does not necessarily ensure timely initiation of treatment, which may be delayed or declined for a variety of reasons [32]. US providers report that delays in insurance approvals can delay initiation of treatment [21]. In Utah, during the first 5 years of screening, the median age at treatment was 19 days for four infants with 2 SMN2 copies and 47 days for five infants with 3 SMN2 copies [16]. In European countries where insurance preapproval is not required, other factors, including elevated AAV9 antibody titers in the infant and prematurity, can delay initiation of OA gene therapy [33].
Follow-up data from two German states that had implemented screening for SMA found that, of 44 infants detected with 2 or 3 SMN2 copies, the mean age at initiation of treatment was 1.3 months, with a skewed distribution and a standard deviation of 2.2 months [32]. The same study reported that, in data from a German and Austrian clinical SMA registry, similar patients diagnosed in areas without screening began treatment at an average age of 10.7 months, with worse survival and motor function than the screened cohort. The magnitude of the reduction in age at initiation of treatment during the early phase of SMA screening implementation in Germany may be conservative if timely detection and intervention continue to increase over time.
In the Medicaid data, the percentage of infants with presumed SMA detected within 24 months of birth that had an SMA claim within the first month rose from 13.5% in 2016 to 23.4% in 2018 (Table 2). That increase preceded the widespread implementation of SMA NBS. Testing for SMA soon after birth in the absence of NBS may have been based on having an affected older sibling. Other newborns may have been tested for SMA because their mother had tested positive on carrier screening. Carrier screening for SMA has been recommended for patients who are pregnant or seeking to become pregnant by the American College of Medical Genetics and Genomics since 2008 and by the American College of Obstetrics and Gynecology since 2017 [34]. Finally, increases in early diagnosis of SMA may have reflected increased clinical awareness of SMA associated with the FDA approval of nusinersen in 2016.
The findings are subject to limitations. One limitation is attrition due to disenrollment from health plans. For example, roughly 10–15% of infants in the Medicaid birth cohorts appear to have disenrolled from Medicaid or CHIP prior to 24 months (results not reported). Furthermore, the accuracy of diagnosis codes for billing purposes is subject to uncertainty. Administrative databases contain records generated as byproducts of reporting or paying for services and do not contain patient-reported or clinical information. Diagnosis codes are recorded as reasons for healthcare encounters; the presence of a diagnosis code for a condition such as SMA indicates that the visit was related to SMA but does not necessarily mean that a clinical diagnosis had been established. Although it is possible for researchers to assess the validity of diagnosis codes or code-based case definitions through linkage of administrative and clinical databases, such studies are often not available for rare disorders, and no validation studies for SMA diagnosis codes have been published.
Although the optimal approach for identifying SMA cases in administrative data has not been established, the administrative birth prevalence estimates of SMA reported here appear generally consistent with published estimates. According to US NBS data, the birth prevalence of SMA is just under 7 per 100,000 live births [17]. On the other hand, if diagnosis codes for SMA are sometimes carried over in electronic health records without final confirmation, the number of presumed SMA cases in recent birth cohorts could be overstated by our algorithm, which treats the presence of SMA diagnosis codes in two or more outpatient claims at least one week apart as equivalent to a presumptive diagnosis.
Another limitation is that neither database includes complete records of services received for individuals with both Medicaid and private coverage. The CMS Medicaid database contains a flag variable to identify enrollees with dual coverage through other insurance types. Approximately 5% of infants with Medicaid coverage in this study also had private insurance or other third-party coverage. It is unlikely that missing records for services reimbursed by non-Medicaid payers affected estimates of administrative prevalence, since dually enrolled infants with SMA likely had encounters with SMA diagnosis codes recorded in both Medicaid and private insurance databases.
Further analyses of claims databases with information on the state of birth could assess the timeliness of detection relative to the timing of SMA NBS implementation across states. The platform used in this preliminary analysis to access MarketScan Commercial claims data does not allow for identification of the state of birth.
5. Conclusions
This preliminary analysis of US health insurance claims data confirms the increase in the detection of SMA in early infancy following the implementation of SMA screening in US NBS programs beginning in 2018. Timely detection by 3–4 weeks of age enables initiation of treatment before 6 weeks of age. Future analyses of the timing of treatment initiation could examine clinical registry and survey data with more complete records of treatments.
Author Contributions
Conceptualization, S.D.G., M.G., G.K.Y. and A.N.; methodology, S.D.G., K.H. and A.N.; validation, S.D.G. and K.H.; formal analysis, S.D.G. and K.H.; writing—original draft preparation, S.D.G. and A.N.; writing—review and editing, S.D.G., J.M.K., K.A.K.L., A.G., K.H., G.K.Y., A.N. and M.G.; supervision, M.G. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Data Availability Statement
The research data used in this study are not publicly available because they are proprietary databases licensed for use by CDC staff under approved data use agreements and cannot be shared with other individuals or groups.
Conflicts of Interest
The authors declare no conflicts of interest.
Abbreviations
The following abbreviations are used in this manuscript:
| SMA | Spinal muscular atrophy |
| SMN | Survival motor neuron |
| SCID | Severe combined immunodeficiency |
| NBS | Newborn screening |
| OA | Onasemnogene abeparvovec |
| RUSP | Recommended Uniform Screening Panel |
| US | United States |
| CMS | Centers for Medicare & Medicaid Services |
| CDC | Centers for Disease Control and Prevention |
| CHIP | Children’s Health Insurance Programs |
| FDA | Food and Drug Administration |
| AAV9 | Adeno-associated virus serotype 9 |
| ICD | International Classification of Diseases |
References
- National Academies of Science, Engineering, and Medicine. Newborn Screening in the United States: A Vision for Sustaining and Advancing Excellence; National Academies Press: Washington, DC, USA, 2025. [Google Scholar]
- Centers for Disease Control and Prevention. Ten great public health achievements—United States, 2001–2010. MMWR Morb. Mortal. Wkly. Rep. 2011, 60, 619–623. [Google Scholar]
- US Department of Health and Human Services. Newborn Screening Timeliness Goals. Available online: https://www.hrsa.gov/advisory-committees/heritable-disorders/newborn-screening-timeliness#:~:text=Initial%20NBS%20specimens%20should%20be,September%202017 (accessed on 18 November 2025).
- Jones, E.; Singh, S.; McKasson, S.; Sheller, R.; Ojodu, J.; Comer, A. Learning Collaborative to Support Continuous Quality Improvement in Newborn Screening. Int. J. Neonatal Screen. 2025, 11, 70. [Google Scholar] [CrossRef]
- Bach, J.R.; Baird, J.S.; Plosky, D.; Navado, J.; Weaver, B. Spinal muscular atrophy type 1: Management and outcomes. Pediatr. Pulmonol. 2002, 34, 16–22. [Google Scholar] [CrossRef]
- Calucho, M.; Bernal, S.; Alias, L.; March, F.; Vencesla, A.; Rodriguez-Alvarez, F.J.; Aller, E.; Fernandez, R.M.; Borrego, S.; Millan, J.M.; et al. Correlation between SMA type and SMN2 copy number revisited: An analysis of 625 unrelated Spanish patients and a compilation of 2834 reported cases. Neuromuscul. Disord. 2018, 28, 208–215. [Google Scholar] [CrossRef] [PubMed]
- Nishio, H.; Niba, E.T.E.; Saito, T.; Okamoto, K.; Takeshima, Y.; Awano, H. Spinal Muscular Atrophy: The Past, Present, and Future of Diagnosis and Treatment. Int. J. Mol. Sci. 2023, 24, 11939. [Google Scholar] [CrossRef] [PubMed]
- Kemper, A.R.; Lam, K.; Comeau, A.M.; Kwon, J.; Green, N.S.; Ojodu, J.; Grosse, S.; Prosser, L.A.; Jones, E.; Tanksley, S. Evidence-Based Review of Newborn Screning for Spinal Muscular Atrophy (SMA): Final Report (v5.2); Maternal and Child Health Bureau, Department of Health and Human Services: Rockville, MD, USA, 2018. [Google Scholar]
- Pearson, S.D.; Thokala, P.; Stevenson, M.; Rind, D. The Effectiveness and Value of Treatments for Spinal Muscular Atrophy. J. Manag. Care Spec. Pharm. 2019, 25, 1300–1306. [Google Scholar] [CrossRef] [PubMed]
- Crawford, T.O.; Swoboda, K.J.; De Vivo, D.C.; Bertini, E.; Hwu, W.L.; Finkel, R.S.; Kirschner, J.; Kuntz, N.L.; Nazario, A.N.; Parsons, J.A.; et al. Continued benefit of nusinersen initiated in the presymptomatic stage of spinal muscular atrophy: 5-year update of the NURTURE study. Muscle Nerve 2023, 68, 157–170. [Google Scholar] [CrossRef]
- Glascock, J.; Sampson, J.; Connolly, A.M.; Darras, B.T.; Day, J.W.; Finkel, R.; Howell, R.R.; Klinger, K.W.; Kuntz, N.; Prior, T.; et al. Revised Recommendations for the Treatment of Infants Diagnosed with Spinal Muscular Atrophy via Newborn Screening Who Have 4 Copies of SMN2. J. Neuromuscul. Dis. 2020, 7, 97–100. [Google Scholar] [CrossRef]
- Lee, F.K.; Greene, C.; Mercer, K.; Taylor, J.; Yazdanpanah, G.; Vogt, R.; Lee, R.; Cuthbert, C.; Cordovado, S. CDC’s Laboratory Activities to Support Newborn Screening for Spinal Muscular Atrophy. Int. J. Neonatal Screen. 2024, 10, 51. [Google Scholar] [CrossRef]
- Kellar-Guenther, Y.; McKasson, S.; Hale, K.; Singh, S.; Sontag, M.K.; Ojodu, J. Implementing Statewide Newborn Screening for New Disorders: U.S. Program Experiences. Int. J. Neonatal Screen. 2020, 6, 35. [Google Scholar] [CrossRef]
- Singh, S.; Ojodu, J.; Kemper, A.R.; Lam, W.K.K.; Grosse, S.D. Implementation of Newborn Screening for Conditions in the United States First Recommended during 2010–2018. Int. J. Neonatal Screen. 2023, 9, 20. [Google Scholar] [CrossRef]
- Shih, S.T.F.; Keller, E.; Wiley, V.; Farrar, M.A.; Wong, M.; Chambers, G.M. Modelling the Cost-Effectiveness and Budget Impact of a Newborn Screening Program for Spinal Muscular Atrophy and Severe Combined Immunodeficiency. Int. J. Neonatal Screen. 2022, 8, 45. [Google Scholar] [CrossRef] [PubMed]
- Wong, K.N.; McIntyre, M.; Cook, S.; Hart, K.; Wilson, A.; Moldt, S.; Rohrwasser, A.; Butterfield, R.J. A Five-Year Review of Newborn Screening for Spinal Muscular Atrophy in the State of Utah: Lessons Learned. Int. J. Neonatal Screen. 2024, 10, 54. [Google Scholar] [CrossRef] [PubMed]
- Gaviglio, A.; McKasson, S.; Singh, S.; Ojodu, J. Infants with Congenital Diseases Identified through Newborn Screening-United States, 2018–2020. Int. J. Neonatal Screen. 2023, 9, 23. [Google Scholar] [CrossRef] [PubMed]
- Vrscaj, E.; Dangouloff, T.; Osredkar, D.; Servais, L.; SMA NBS World Study Group. Newborn screening programs for spinal muscular atrophy worldwide in 2023. J. Neuromuscul. Dis. 2024, 11, 1180–1189. [Google Scholar] [CrossRef]
- Cooper, K.; Nalbant, G.; Sutton, A.; Harnan, S.; Thokala, P.; Chilcott, J.; McNeill, A.; Bessey, A. Systematic Review of Newborn Screening Programmes for Spinal Muscular Atrophy. Int. J. Neonatal Screen. 2024, 10, 49. [Google Scholar] [CrossRef]
- Belter, L.; Taylor, J.L.; Jorgensen, E.; Glascock, J.; Whitmire, S.M.; Tingey, J.J.; Schroth, M. Newborn Screening and Birth Prevalence for Spinal Muscular Atrophy in the US. JAMA Pediatr. 2024, 178, 946–949. [Google Scholar] [CrossRef]
- Zaidman, C.M.; Crockett, C.D.; Wedge, E.; Tabatabai, G.; Goedeker, N. Newborn Screening for Spinal Muscular Atrophy: Variations in Practice and Early Management of Infants with Spinal Muscular Atrophy in the United States. Int. J. Neonatal Screen. 2024, 10, 58. [Google Scholar] [CrossRef]
- National Academies of Science, Engineering, and Medicine. Birth Settings in America: Outcomes, Quality, Access, and Choice; National Academies Press: Washington, DC, USA, 2020. [Google Scholar]
- Grosse, S.D.; Nichols, P.; Nyarko, K.; Maenner, M.; Danielson, M.L.; Shea, L. Heterogeneity in Autism Spectrum Disorder Case-Finding Algorithms in United States Health Administrative Database Analyses. J. Autism Dev. Disord. 2022, 52, 4150–4163. [Google Scholar] [CrossRef]
- Fox, D.; To, T.M.; Seetasith, A.; Patel, A.M.; Iannaccone, S.T. Adherence and Persistence to Nusinersen for Spinal Muscular Atrophy: A US Claims-Based Analysis. Adv. Ther. 2023, 40, 903–919. [Google Scholar] [CrossRef]
- Whitney, D.G.; Knierbein, E.E.N.; Daunter, A.K. Prevalence of morbidities across the lifespan for adults with spinal muscular atrophy: A retrospective cohort study. Orphanet J. Rare Dis. 2023, 18, 258. [Google Scholar] [CrossRef] [PubMed]
- Belter, L.; Cruz, R.; Kulas, S.; McGinnis, E.; Dabbous, O.; Jarecki, J. Economic burden of spinal muscular atrophy: An analysis of claims data. J. Mark. Access Health Policy 2020, 8, 1843277. [Google Scholar] [CrossRef] [PubMed]
- Mouchet, J.; Roumpanis, S.; Gaki, E.; Lipnick, S.; Oskoui, M.; Scalco, R.S.; Darras, B.T. Disease Burden of Spinal Muscular Atrophy: A Comparative Cohort Study Using Insurance Claims Data in the USA. J. Neuromuscul. Dis. 2023, 10, 41–53. [Google Scholar] [CrossRef]
- Armstrong, E.P.; Malone, D.C.; Yeh, W.S.; Dahl, G.J.; Lee, R.L.; Sicignano, N. The economic burden of spinal muscular atrophy. J. Med. Econ. 2016, 19, 822–826. [Google Scholar] [CrossRef] [PubMed]
- Chen, G.; Sharif, B.; Gerber, B.; Farris, M.S.; Cowling, T.; Cabalteja, C.; Wu, J.W.; Maturi, B.; Klein-Panneton, K.; Jean, K.M. Epidemiology, healthcare resource utilization and healthcare costs for spinal muscular atrophy in Alberta, Canada. J. Med. Econ. 2021, 24, 51–59. [Google Scholar] [CrossRef]
- Statista. Number of births in the United States from 1990 to 2023. Available online: https://www.statista.com/statistics/195908/number-of-births-in-the-united-states-since-1990/?srsltid=AfmBOorb6KyFB2IlTzpAFtX1ZKn1YN0gfYC7khsvikdM1UQYP3nb-Utd (accessed on 13 November 2025).
- De Vivo, D.C.; Bertini, E.; Swoboda, K.J.; Hwu, W.L.; Crawford, T.O.; Finkel, R.S.; Kirschner, J.; Kuntz, N.L.; Parsons, J.A.; Ryan, M.M.; et al. Nusinersen initiated in infants during the presymptomatic stage of spinal muscular atrophy: Interim efficacy and safety results from the Phase 2 NURTURE study. Neuromuscul. Disord. 2019, 29, 842–856. [Google Scholar] [CrossRef]
- Schwartz, O.; Vill, K.; Pfaffenlehner, M.; Behrens, M.; Weiss, C.; Johannsen, J.; Friese, J.; Hahn, A.; Ziegler, A.; Illsinger, S.; et al. Clinical Effectiveness of Newborn Screening for Spinal Muscular Atrophy: A Nonrandomized Controlled Trial. JAMA Pediatr. 2024, 178, 540–547. [Google Scholar] [CrossRef]
- Masson, R.; Gaballo, S.; Caravita, R.; Parravicini, S. Treating Presymptomatic Spinal Muscular Atrophy Patients with Onasemnogene Abeparvovec in Italy: The Role of the National Health System and Drug Supply. Comment on Zaidman et al. Newborn Screening for Spinal Muscular Atrophy: Variations in Practice and Early Management of Infants with Spinal Muscular Atrophy in the United States. Int. J. Neonatal Screen. 2024, 10, 58. Int. J. Neonatal Screen. 2025, 11, 102. [Google Scholar] [CrossRef]
- Santoli, C.M.; Dotters-Katz, S.K.; Sparks, T.N.; Kuller, J.A. An overview of current prenatal genetic screening and diagnosis guidelines. Pregnancy 2025, 1, e70016. [Google Scholar] [CrossRef]
Table 1.
Numbers of infants with SMA diagnosis codes recorded by 1, 3, 12, and 24 months of age, and the number meeting the SMA case definition by 48 months of age, for the 2016–2022 CMS Medicaid birth cohorts.
Table 1.
Numbers of infants with SMA diagnosis codes recorded by 1, 3, 12, and 24 months of age, and the number meeting the SMA case definition by 48 months of age, for the 2016–2022 CMS Medicaid birth cohorts.
| Birth Cohort | Live Births | First SMA Code by Age 1 Month | First SMA Code by Age 3 Months | First SMA Code by Age 12 Months | First SMA Code by Age 24 Months | Total SMA Detected by Age 48 Months |
|---|---|---|---|---|---|---|
| 2016 | 2,246,783 | 17 | 41 | 103 | 126 | 140 |
| 2017 | 2,197,093 | 28 | 49 | 125 | 153 | 188 |
| 2018 | 2,106,098 | 35 | 56 | 115 | 147 | 175 |
| 2019 | 2,048,986 | 49 | 84 | 128 | 142 | 159 |
| 2020 | 1,960,900 | 87 | 113 | 158 | 180 | NA 1 |
| 2021 | 1,944,076 | 101 | 128 | 158 | 169 | NA 1 |
| 2022 | 1,972,770 | 133 | 152 | 174 | NA 2 | NA 1 |
1 NA: Not available, as the potential length of follow-up was less than 1459 days after birth. 2 NA: Not available, as the potential length of follow-up was less than 730 days after birth.
Table 2.
Administrative prevalence of SMA per 100,000 live births at 1, 3, 12, and 24 months of age for the 2016–2022 CMS Medicaid birth cohorts, and the percentage of cases detected by 24 months of age with SMA diagnosis codes recorded in the first month of life.
Table 2.
Administrative prevalence of SMA per 100,000 live births at 1, 3, 12, and 24 months of age for the 2016–2022 CMS Medicaid birth cohorts, and the percentage of cases detected by 24 months of age with SMA diagnosis codes recorded in the first month of life.
| Birth Cohort | By 1 Month | By 3 Months | By 12 Months | By 24 Months | Percent of Those Detected by 24 Months Who Were Detected by 1 Month |
|---|---|---|---|---|---|
| 2016 | 0.8 | 1.8 | 4.6 | 5.6 | 13.5% |
| 2017 | 1.3 | 2.2 | 5.6 | 6.9 | 18.4% |
| 2018 | 1.5 | 2.5 | 5.2 | 6.5 | 23.4% |
| 2019 | 2.1 | 3.9 | 6.0 | 6.6 | 32.4% |
| 2020 | 4.4 | 5.7 | 7.9 | 8.9 | 49.1% |
| 2021 | 5.1 | 6.4 | 8.0 | 8.5 | 60.6% |
| 2022 | 6.6 | 7.5 | 8.5 | NA 1 | NA 1 |
1 NA: Not available, as the potential length of follow-up was less than 730 days after birth for the 2022 birth cohort.
Table 3.
Number of SMA diagnosis codes recorded by 1, 3, 12, and 24 months of age, and the number meeting the SMA case definition by 48 months of age for the 2017–2023 Merative® MarketScan Commercial birth cohorts.
Table 3.
Number of SMA diagnosis codes recorded by 1, 3, 12, and 24 months of age, and the number meeting the SMA case definition by 48 months of age for the 2017–2023 Merative® MarketScan Commercial birth cohorts.
| Birth Cohort | Live Births | First SMA Code by Age 1 Month | First SMA Code by Age 3 Months | First SMA Code by Age 12 Months | First SMA Code by Age 24 Months | Total SMA Detected by Age 48 Months |
|---|---|---|---|---|---|---|
| 2017 | 200,810 | 0 | 1 | 2 | 3 | 3 |
| 2018 | 185,372 | 1 | 3 | 8 | 11 | 11 |
| 2019 | 173,079 | 7 | 9 | 13 | 15 | 15 |
| 2020 | 158,203 | 7 | 7 | 8 | 8 | 9 |
| 2021 | 150,659 | 8 | 9 | 10 | 11 | 11 |
| 2022 | 142,260 | 10 | 11 | 12 | 12 | NA 1 |
| 2023 | 141,926 | 15 | 15 | 15 | NA 2 | NA 1 |
1 NA: Not available, as the potential length of follow-up was less than 1459 days after birth. 2 NA: Not available, as the potential length of follow-up was less than 730 days after birth.
Table 4.
Administrative prevalence of SMA per 100,000 live births at 1, 3, 12, and 24 months of age for the 2018–2023 Merative® MarketScan Commercial birth cohorts, and the percentage of cases detected by 24 months of age with SMA diagnosis codes recorded in the first month of life.
Table 4.
Administrative prevalence of SMA per 100,000 live births at 1, 3, 12, and 24 months of age for the 2018–2023 Merative® MarketScan Commercial birth cohorts, and the percentage of cases detected by 24 months of age with SMA diagnosis codes recorded in the first month of life.
| Birth Cohort | By 1 Month | By 3 Months | By 12 Months | By 24 Months | Percent of Those Detected by 24 Months Who Were Detected by 1 Month |
|---|---|---|---|---|---|
| 2018 | 0.6 | 1.7 | 4.4 | 6.1 | 9.1% |
| 2019 | 4.1 | 5.3 | 7.7 | 8.9 | 46.7% |
| 2020 | 4.6 | 4.6 | 5.2 | 5.2 | 87.5% |
| 2021 | 5.4 | 6.1 | 6.8 | 7.4 | 72.7% |
| 2022 | 7.1 | 7.8 | 8.6 | 8.6 | 83.3% |
| 2023 | 10.8 | 10.8 | 10.8 | NA 1 | NA 1 |
1 NA: Not available, as the potential length of follow-up was less than 730 days after birth for the 2023 birth cohort.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2026 by the authors. Published by MDPI on behalf of the International Society for Neonatal Screening. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.
Share and Cite
MDPI and ACS Style
Grosse, S.D.; Hong, K.; Yazdanpanah, G.K.; Nash, A.; Gaviglio, A.; Gaffney, M.; Lawrence, K.A.K.; Kwon, J.M. Trends in the Timeliness of Spinal Muscular Atrophy Detection in US Infants, 2016–2023. Int. J. Neonatal Screen. 2026, 12, 9. https://doi.org/10.3390/ijns12010009
AMA Style
Grosse SD, Hong K, Yazdanpanah GK, Nash A, Gaviglio A, Gaffney M, Lawrence KAK, Kwon JM. Trends in the Timeliness of Spinal Muscular Atrophy Detection in US Infants, 2016–2023. International Journal of Neonatal Screening. 2026; 12(1):9. https://doi.org/10.3390/ijns12010009
Chicago/Turabian StyleGrosse, Scott D., Kai Hong, Golriz K. Yazdanpanah, Ashley Nash, Amy Gaviglio, Marcus Gaffney, Kendra A. K. Lawrence, and Jennifer M. Kwon. 2026. "Trends in the Timeliness of Spinal Muscular Atrophy Detection in US Infants, 2016–2023" International Journal of Neonatal Screening 12, no. 1: 9. https://doi.org/10.3390/ijns12010009
APA StyleGrosse, S. D., Hong, K., Yazdanpanah, G. K., Nash, A., Gaviglio, A., Gaffney, M., Lawrence, K. A. K., & Kwon, J. M. (2026). Trends in the Timeliness of Spinal Muscular Atrophy Detection in US Infants, 2016–2023. International Journal of Neonatal Screening, 12(1), 9. https://doi.org/10.3390/ijns12010009
Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.
