Comparison of two sweat test systems for the diagnosis of cystic fibrosis in newborns

Objectives In the national newborn screening programme for CF in Switzerland, we compared the performance of two sweat test methods, by investigating the feasibility and diagnostic performance of the Macroduct® collection method (with chloride mesurement) and Nanoduct® test (measuring conductivity) for diagnosing CF. Study‐Design We included all newborns with a positive screening result between 2011 and 2015 who were referred to a CF‐centre for sweat testing. In the CF‐centre, a Macroduct and Nanoduct sweat test were performed simultaneously. If sweat test results were positive or borderline, a DNA analysis was performed. Final diagnosis was based on genetic mutations. Results Over 5 years, 445 children were screened positive and in 413 (114 with CF) at least one sweat test was performed (median age at first test, 22 days); both tests were performed in 371 children. A sweat test result was more often available with the Nanoduct compared to the Macroduct (79 vs 60%, P