Cystic fibrosis neonatal screening (CFNS), based on double determination of immunoreactive trypsinogen ([IRT] [IRT1/IRT2]), has been available in Andalusia since May 2011. If screening is positive, a sweat test is performed, and if that is positive or inconclusive, genetic testing is requested.

To analyze CFNS, based on results from the first 4.5 years of the program.

Prospective descriptive study of neonates undergoing CFNS. IRT levels, sweat chloride, and mutations were recorded. Statistical analysis was performed using SPSS 12.0.

Between May 2011 and December 2016, 474,953 neonates underwent CFNS. Of these, 1087 (0.23%) had elevated IRT2. Since CFNS was introduced, 73 cases of cystic fibrosis were diagnosed; 60 were diagnosed by positive CFNS, and 13 were diagnosed by other means. In one case, the patient developed a typical clinical picture of cystic fibrosis, but had not undergone CFNS at the decision of the parents; the remaining 12 had a negative CFNS (false negatives). Of these, one patient was diagnosed before symptoms developed, as his twin brother had a positive CFNS result; another had chloride at the upper limit of normal, and was subsequently diagnosed with genetic testing before symptoms appeared; and 10 patients developed clinical signs and symptoms. Excluding patients with meconium ileus, sensitivity and specificity of the CFNS program were 85.71% and 99.78%, respectively. The incidence of the disease in Andalusia is 1/6506 live births.

These results are a basis for reflection on possible areas for improvement of the CFNS algorithm, and thought may be given to the introduction of genetic studies to increase sensitivity and reduce false positives.

Andalucía dispone de screening neonatal de fibrosis quística (SNFQ) desde mayo 2011, basado en doble determinación de tripsinógeno inmunorreactivo ([TIR] [TIR1/TIR2]). Si el screening es positivo realizamos un test del sudor y si es positivo o dudoso solicitamos genética.

Analizar el SNFQ, basado en los resultados de los primeros 4,5 años.

Estudio descriptivo prospectivo de los neonatos sometidos a SNFQ. Se recogen los niveles de TIR, cloruro en sudor, mutaciones. Mediante SPSS12.0 se realizó análisis estadístico.

Desde mayo 2011 a diciembre 2016, 474.953 neonatos fueron sometidos a SNFQ. Mil ochenta y siete (0,23%) presentaron TIR2 elevado. Desde la implantación del SNFQ se diagnosticaron 73 casos con fibrosis quística; 60 de ellos fueron diagnosticados mediante un SNFQ positivo, mientras que 13 no. Concretamente un paciente comenzó con clínica clásica de fibrosis quística y se comprobó que no se había realizado el SNFQ por decisión paterna; los 12 restantes tuvieron un SNFQ negativo (falsos negativos). De estos, un paciente fue diagnosticado presintomáticamente al tener su hermano gemelo con SNFQ positivo; otro con cloruro en el límite alto de la normalidad se diagnosticó presintomáticamente mediante genética; 10 pacientes comenzaron clínicamente. Excluyendo los pacientes con íleo meconial, la sensibilidad y especificidad del programa de SNFQ asciende al 85,71 y 99,78% respectivamente. La incidencia de la enfermedad en Andalucía es de 1/6.506 recién nacidos vivos.

Los presentes resultados nos permiten reflexionar sobre posibles áreas de mejoras adicionales del algoritmo del SNFQ, que debe pasar por la introducción de estudios genéticos para así aumentar la sensibilidad y disminuir los falsos positivos.