Sweat conductivity and coulometric quantitative test in neonatal cystic fibrosis screening

Journal Title: Jornal de Pediatria - Year 2015, Vol 91, Issue 6

Abstract

Objective To compare the results obtained with the sweat test using the conductivity method and coulometric measurement of sweat chloride in newborns (NBs) with suspected cystic fibrosis (CF) in the neonatal screening program. Methods The sweat test was performed simultaneously by both methods in children with and without CF. The cutoff values to confirm CF were >50mmol/L in the conductivity and >60mmol/L in the coulometric test. Results There were 444 infants without CF (185 males, 234 females, and 24 unreported) submitted to the sweat test through conductivity and coulometric measurement simultaneously, obtaining median results of 32mmol/L and 12mmol/L, respectively. For 90 infants with CF, the median values of conductivity and coulometric measurement were 108mmol/L and 97mmol/L, respectively. The false positive rate for conductivity was 16.7%, and was higher than 50mmol/L in all patients with CF, which gives this method a sensitivity of 100% (95% CI: 93.8–97.8), specificity of 96.2% (95% CI: 93.8–97.8), positive predictive value of 83.3% (95% CI: 74.4–91.1), negative predictive value of 100% (95% CI: 90.5–109.4), and 9.8% accuracy. The correlation between the methods was r=0.97 (p>0.001). The best suggested cutoff value was 69.0mmol/L, with a kappa coefficient=0.89. Conclusion The conductivity test showed excellent correlation with the quantitative coulometric test, high sensitivity and specificity, and can be used in the diagnosis of CF in children detected through newborn screening.

Authors and Affiliations

Mouseline Domingos

Keywords

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  • EP ID EP554581
  • DOI 10.1016/j.jped.2015.03.003
  • Views 50
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How To Cite

Mouseline Domingos (2015). Sweat conductivity and coulometric quantitative test in neonatal cystic fibrosis screening. Jornal de Pediatria, 91(6), 590-595. https://europub.co.uk/articles/-A-554581