Characterizing CFTR Modulated Changes in Sweat Chloride and Clinical Outcomes

This is a multicenter, cross-sectional, cohort study which will collect contemporary SC values from approximately 1000 CF patients prescribed and currently receiving commercially approved CFTR modulator therapies. Eligible subjects who have been prescribed and chronically taking a commercially approved CFTR modulator for at least 3 months will be enrolled for a single visit to collect sweat to be analyzed for SC at their local site laboratory. Limited clinical data obtained at this visit will be augmented by retrospective and prospective data obtained from the CFFPR. Study subjects who have been prescribed and switch to an alternative commercially approved CFTR modulator will be approached to re-enroll in the study after being on the alternative modulator for at least 3 months so that a new SC value can be obtained