RESUMEN
From 2007 to 2014 the New York State (NYS) Newborn Screening (NBS) program screened 2 million newborns for congenital adrenal hyperplasia (CAH). The data was analyzed to determine factors that affect 17α-hydroxyprogesterone levels and assist in developing algorithm changes that would improve the positive predictive value of the methodology being used. The concentration of 17-OHP in dried blood spots was measured using the AutoDELFIA Neonatal 17-OHP kit (Perkin Elmer, Turku, Finland). During the 8 year period of this study 2476 babies were referred, 105 babies were diagnosed with CAH (90 with the salt-wasting (SW), 8 with simple virilizing (SV), 5 with non-classical CAH, and 2 with another enzyme deficiency) and, 14 with possible CAH. Three false negative cases with SV-CAH were reported to the program. Of the total 108 known cases, 74 (69%) infants were detected by newborn screening in the absence of clinical information, or, known family history. The incidence of CAH in NYS is 1 in 18,170 with a ratio of SW to SV of 8.2:1. The incidence of CAH is lower in Black infants than in White, Hispanic and Asian infants. Despite a lower mean birth weight, female infants have a lower mean 17-OHP value than male infants and are under-represented in the referred category. As per other NBS programs the false positive rate is exacerbated by prematurity/low birth weight and by over-early specimen collection.
RESUMEN
Newborn screening for cystic fibrosis (CF), a chronic progressive disease affecting mucus viscosity, has been beneficial in both improving life expectancy and the quality of life for individuals with CF. In New York State from 2007 to 2012 screening for CF involved measuring immunoreactive trypsinogen (IRT) levels in dried blood spots from newborns using the IMMUCHEM(™) Blood Spot Trypsin-MW ELISA kit. Any specimen in the top 5% IRT level underwent DNA analysis using the InPlex(®) CF Molecular Test. Of the 1.48 million newborns screened during the 6-year time period, 7631 babies were referred for follow-up. CF was confirmed in 251 cases, and 94 cases were diagnosed with CF transmembrane conductance regulated-related metabolic syndrome or possible CF. Nine reports of false negatives were made to the program. Variation in daily average IRT was observed depending on the season (4-6 ng/ml) and kit lot (<3 ng/ml), supporting the use of a floating cutoff. The screening method had a sensitivity of 96.5%, specificity of 99.6%, positive predictive value of 4.5%, and negative predictive value of 99.5%. CONCLUSION: Considerations for CF screening algorithms should include IRT variations resulting from age at specimen collection, sex, race/ethnicity, season, and manufacturer kit lots. WHAT IS KNOWN: Measuring IRT level in dried blood spots is the first-tier screen for CF. Current algorithms for CF screening lead to substantial false-positive referral rates. WHAT IS NEW: IRT values were affected by age of infant when specimen is collected, race/ethnicity and sex of infant, and changes in seasons and manufacturer kit lots The prevalence of CF in NYS is 1 in 4200 with the highest prevalence in White infants (1 in 2600) and the lowest in Black infants (1 in 15,400).