SCID Disease Screening in Newborns Saves Lives

Researchers report that introducing widespread neonatal screening for the fatal disease severe combined immunodeficiency, or SCID, followed by early treatment increased the five-year survival rate of children with the disorder from 73% before the introduction of screening to 88% since. 92.5 percent of infants whose disease was suspected due to newborn screening rather than illness or family history survived at least five years after treatment. These results demonstrate for the first time that newborn screening facilitated the early identification of neonates with SCID, resulting in prompt treatment before life-threatening infections occurred, thereby increasing the proportion of children who survived to age 5 or beyond. The retrospective investigation published in The Lancet was led by researchers from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and their colleagues.

“This study definitively shows that population-wide newborn screening for SCID has made it possible to save the lives of many more children with the disorder than ever before,” said NIAID Acting Director Hugh Auchincloss, M.D. “We hope these findings will encourage more countries to screen newborns for this devastating disease.”

SCID is a rare disorder caused by abnormalities in genes involved in the generation and function of infection-fighting immune cells. SCID infants appear healthy at birth, yet they are extremely vulnerable to severe illnesses. The illness is deadly, usually within the first year or two of life, unless the newborn receives an immune-restoring treatment such as a stem-cell transplant, gene therapy, or enzyme therapy. Each year, 40 to 80 babies in the United States and Canada are diagnosed with SCID. Because most nations do not currently screen for SCID, the global number of newborns born with the condition is unknown. In locations where inbreeding is common, the incidence ranges from 1 newborn per 2,000 live births to 1 infant every 60,000 live births.

In 2005, NIH researchers developed a newborn screening test for SCID. With the progressive use of the test, it is now able to diagnose the disease in newborns before symptoms occur, avoid infection, and deliver life-saving treatment early. Individual states in the United States and Canadian provinces began screening babies for SCID in 2008, with Wisconsin leading the way. By the end of 2018, all 50 states, Washington, D.C., and two U.S. territories have begun screening newborns for the disease. Currently, seven Canadian provinces and territories do so.

Several prior research suggested that screening all newborns for SCID improved survival, but none proved it. As a result, the NIH-funded Primary Immune Deficiency Treatment Consortium (PIDTC) set out to determine whether the introduction of population-wide newborn screening for SCID enhanced infant survival. The PIDTC is part of the NCATS Rare Diseases Clinical Research Network, which includes 47 centers across North America with the same goal of improving health outcomes for patients with rare, life-threatening, hereditary immune system illnesses.

PIDTC researchers examined data on over 900 infants with confirmed SCID who were treated with a donation of blood-forming stem cells from a non-genetically matched donor at one of 34 sites in the United States or Canada between 1982 and 2018. The researchers compared the five-year overall survival rate of these children between 2010 and 2018, when state and province-wide newborn screening was in place at participating locations, to earlier time periods. The researchers excluded from the study infants who got stem-cell transplants from genetically matched sibling donors because they had great overall survival rates during the study period.

Despite advances in clinical treatment, the five-year overall survival percentage for children with SCID who underwent a stem-cell transplant from a non-genetically matched donor stayed stable at 72% to 73% from 1982 to 2009, but increased to 87% from 2010 to 2018. Between 2010 and 2018, 92.5% of children who received a transplant and whose disease was first diagnosed as a consequence of neonatal screening rather than illness or a family history of SCID survived to age 5 or beyond.

Previous studies had showed that children with SCID who were younger than 3.5 months at the time of transplant and did not have an active infection at the time of transplant had a higher five-year survival rate. An examination of the PIDTC data revealed that both of these characteristics were substantially more common in the era of newborn screening and contributed to an increase in the proportion of infants who survived to the age of five. Furthermore, when comparing 2010-2018 to earlier decades, the percentage of kids with SCID who had never experienced an infection by the time of transplant was significantly higher, fuelling the survival improvement. Furthermore, regardless of the transplant technique utilized, the percentage of children who survived to the age of 5 was higher in 2010-2018 than in previous decades.

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