Elsevier

Journal of Cystic Fibrosis

Volume 12, Issue 6, December 2013, Pages 706-713
Journal of Cystic Fibrosis

Original Article
The predictive potential of the sweat chloride test in cystic fibrosis patients with the G551D mutation

https://doi.org/10.1016/j.jcf.2013.03.004Get rights and content
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Abstract

Background

Ivacaftor, a cystic fibrosis transmembrane regulator (CFTR) potentiator, decreased sweat chloride concentrations and improved clinical measures in cystic fibrosis (CF) patients with the G551D mutation.

Results

Sweat chloride measurements at day 15 had an overall positive predictive value (PPV) of 86.3%, a negative predictive value (NPV) of 65.5%, sensitivity of 73.9%, and specificity of 80.9% for an FEV1 improvement of ≥ 5% from baseline at week 16. For ivacaftor patients the median FEV1 improvement was 16.7%; for placebo patients 0.4%. For patients aged 6–11 years who received ivacaftor and who had a sweat chloride decrease of ≥ 40 mmol/L from baseline at day 15, a median weight gain of 11.2% at week 16, compared to 6% for those with a smaller decrease was observed.

Conclusions

Changes in sweat chloride concentration at day 15 following treatment with ivacaftor may have sufficient predictive potential to identify individuals that show improvement in pulmonary function and weight gain after 16 weeks of treatment.

Keywords

PPV
Clinical outcomes
Ivacaftor
FEV1
Weight

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