Newborn Screening For Inherited Metabolic Diseases Has Long-Term Benefits

A new study shows that newborn screening (NBS) for inherited metabolic diseases has long-term benefits for affected individuals, "thus proving the success of this program of secondary prevention," the study team says.

Since the late 1990s, tandem mass spectrometry has been increasingly used in NBS programs, allowing identification of 30 inherited metabolic diseases (IMDs). However, gauging success of these programs has been hampered by the lack of data regarding long-term outcomes.

In a report in Pediatrics, Dr. Ulrike Mutze from University Hospital Heidelberg, Germany and colleagues report the long-term clinical outcomes in 306 patients with IMDs identified between 1999 and 2016 through NBS; 115 patients with phenylketonuria and 191 with other IMDs with a lifelong risk for metabolic decompensation. The patients were followed until an average age of 6.2 years (maximum, 17.4 years).

According to the authors, "In the majority of individuals with a risk of decompensation (74.3%), these potentially life-threatening episodes were prevented."

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Overall, 49 of the 191 individuals (25.7%) at risk experienced at least one metabolic decompensation; in 28 (14.7%) this happened before the NBS result was known. "Noteworthy, none of the neonatal decompensations occurred after the report of the positive NBS result," they report.

In addition, the majority of affected individuals did not develop permanent disease-specific signs (75.9%), had normal development (95.6%) and normal cognitive outcome (87.7%) and most attended regular kindergarten and primary school (95.2%).

"This demonstrates that not only individuals with phenylketonuria, serving as a benchmark, but also those with lifelong risk for metabolic decompensation had a favorable long-term outcome," Dr. Mutze and colleagues say.

Germany's NBS program for IMDs, they conclude, which allows an early and mostly (>90%) asymptomatic diagnosis with immediate access to specialized metabolic therapy, "is a highly successful program of secondary prevention. It serves as a major prerequisite of early diagnosis and timely start of therapy, resulting in a favorable clinical outcome."

"Observational longitudinal studies, an often-neglected part of NBS programs, are indispensable to precisely evaluate the long-term health benefit and life-changing impact of NBS for individuals with rare diseases," they add.

In an editorial, Dr. Cynthia Powell, from University of North Carolina at Chapel Hill, notes that in the U.S., only a few states track patients beyond the initial short-term follow-up period.

"There is limited funding for long-term follow-up tracking and data entry, and patient tracking is difficult. National registries and flow of data from electronic medical record systems to public health NBS programs would optimize the ability to track patient outcomes, establish evidence-based best practices, improve quality of care, and assess the needs of patients and families," she writes.

"A framework for assessing outcomes from NBS has been proposed, but only through acknowledgment of the importance of this within the larger context of improving health outcomes of children and its implementation will the true benefits of NBS be realized. Mutze et al provide an excellent example in this important article of how such data can be used to evaluate the health benefits and demonstrate the positive impact of NBS," Dr. Powell concludes.

—Reuters Staff

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