Impact of the inclusion of second-tier tests in the newborn screening program of Catalonia and in other international programs.

• Published in: Revista espanola de salud publica Vol. 94
• Main Authors: Pajares García, Sonia, López Galera, Rosa Mª, Marín Soria, Jose Luis, Argudo Ramírez, Ana, González de Aledo-Castillo, Jose Manuel, Ribes Rubió, Antonia, Prats Viedma, Blanca, Asso Ministral, Laia, García-Villoria, Judit
• Format: Journal Article
• Language: Spanish
• Published: Spain 16.12.2020
• Subjects: Anxiety - etiology; Anxiety - prevention & control; Biomarkers - blood; Cystic Fibrosis - blood; Cystic Fibrosis - diagnosis; False Positive Reactions; Family - psychology; Humans; Infant, Newborn; International Cooperation; Metabolism, Inborn Errors - blood; Metabolism, Inborn Errors - diagnosis; Neonatal Screening - methods; Neonatal Screening - psychology; Reproducibility of Results; Sensitivity and Specificity; Severe Combined Immunodeficiency - blood; Severe Combined Immunodeficiency - diagnosis; Spain; Stress, Psychological - etiology; Stress, Psychological - prevention & control; Tandem Mass Spectrometry - methods; Spain; Immunoassay; Lysosomal diseases; Inherited metabolic diseases; Severe combined immunodeficiency; Newborn screening; Cystic fibrosis; X-ALD; Congenital adrenal hyperplasia; Mass spectrometry; Second-tier test; Spain
• ISSN: 2173-9110

Newborn screening programmes (NBSP) have experienced a qualitative breakthrough due to the implementation of tandem mass spectrometry. However, the tests used give rise to false positives (FP) generating an excessive request for second samples with the consequent anxiety of the families. In order to avoid this problem several programmes have developed second-tier tests (2TT). This article presents our experience in the implementation of 2TT in the NBSP of Catalonia, as well as in other international programmes. From 2004 to the present, 2TT tests have been developed for more than 30 diseases. The use of 2TT helps to decrease the FP rate and increase the positive predictive value (PPV). In the NBSP of Catalonia, the implementation of 2TT for the detection of methylmalonic and propionic acidemias, homocystinurias, maple syrup disease and citrulinaemia, has managed to increase the PPV to 95% and decrease the PF rate to less than 0.01%. In cystic fibrosis, the application of 2TT slightly increases PPV but with a significant decrease in the request for second samples and in the number of cases referred to clinical units. The introduction of 2TT in the NBSP allows to reduce considerably the FP, decreases the number of requested samples, as well as both anxiety and stress of the families, at the same time that the hospital costs are reduced and the PPV is increased, improving notably the efficiency of the NBSP.