Study design (if review, criteria of inclusion for studies)
placebo-controlled, multicenter trial - Authors examined data from a Phase 2 trial (NCT00457821)
Participants
of ivacaftor, a CFTR potentiator, in cystic fibrosis (CF) patients with a G551D mutation
Interventions
Ivacaftor. Sweat chloride and nasal potential difference (NPD) to estimate CFTR activity. Sweat chloride and NPD were secondary endpoints in this placebo-controlled, multicenter trial.
Outcome measures
Differences between dose-groups and assess ivacaftor treatment effects (CFTR activity)
Main results
Within-patient sweat chloride determinations showed sufficient precision to detect differences between dose-groups and assess ivacaftor treatment effects. Analysis of changes in sweat chloride and NPD demonstrated that patients treated with ivacaftor achieved CFTR activity equivalent to approximately 35%-40% of normal.
Authors' conclusions
Sweat chloride is useful in multicenter trials as a biomarker of CFTR activity and to test the effect of CFTR potentiators.