39 Evaluation of the Nanoduct sweat test method after newborn screening for cystic fibrosis

Abstract

Objectives: The approved methods for sweat testing, Gibson-Cooke Pilocarpine Iontophoresis (GCQPIT) or the Wescor Macroduct® Sweat Test system, have many steps that can and do lead to errors. The GCQPIT method is 54 years old, was never intended for newborns, has scared parents and burned infants. Thus, there is a critical need to improve sweat testing technology. Methods: The CF Quantum® Sweat Test (CFQT) System consists of: a. a controller and electrode set that is worn on the arm for pilocarpine iontophoresis; b. a chloride test patch that collects the sample. Chloride ions in the sweat sample come into contact with silver chromate in the test patch, and an ion exchange reaction occurs which creates silver chloride, an insoluble white precipitate formed in the center of the patch; c. a CF Analyzer utilizes a camera and proprietary software that scans the reacted chloride test patch and calculates the concentration of chloride and volume of sweat collected. Herein are preliminary results of a multicenter study. Patients with a previous diagnosis of CF or referred to the sweat testing lab had bilateral GCQPIT or Macroduct® and bilateral CFQT tests performed. Thus far, 57 subjects with a known diagnosis of CF and 56 subjects referred to the sweat test lab have had both tests performed. There is excellent agreement of sweat chloride values between GCQPIT/Macroduct® and CFQT with a Pearson correlation coefficient of r = 0.97. In a post-test questionnaire, 85% of parents/patients preferred the CFQT. Conclusion: The CFQT yields sweat chloride values that are equivalent to that of GCQPIT/Macroduct sweat testing. Supported by: Legacy of Angels Foundation, PolyChrome Medical, Inc.