title: Standardized procedure for measurement of nasal potential difference: an outcome measure in multicenter cystic fibrosis clinical trials.
abstract: Patients with cystic fibrosis (CF) can be discriminated from healthy subjects by measurement of the nasal potential difference, which has become a useful outcome measure for therapies directed toward correcting defective electrolyte transport in CF. A standard operating procedure was developed by a CF Foundation clinical trials network, to be followed by all sites performing collaborative studies. Key variables in the measurement included type of voltmeter, exploring probe, reference electrodes, and solutions used to assess both sodium transport and chloride conductance. Eight sites submitted data on 3-8 normal and 4-5 CF subjects. Baseline voltage, an index of sodium transport, was -18.2 +/- 8.3 mV (mean +/- SD) for normals, and -45.3 +/- 11.4 mV for CF patients. There was no CFTR-mediated chloride secretion in CF subjects, as evidenced by the lack of response to perfusion with zero chloride + beta agonist solutions (+3.2 +/- 3.5 mV) vs. that in normals (-23.7 +/- 10.2 mV). The standardized nasal potential difference measurement minimizes variability between operators and study sites. Valid and consistent results can be attained with trained operators and attention to technical details. These data demonstrate the procedure to be sufficient for multicenter studies in the CF Foundation network.
authors.affiliation: University of Washington, Seattle, Washington, USA. thomas_standaert@chiron.com
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Standaert
authors.forename: Louis
authors.initials: L
authors.lastname: Boitano
authors.forename: Julia
authors.initials: J
authors.lastname: Emerson
authors.forename: Laura J H
authors.initials: LJ
authors.lastname: Milgram
authors.forename: Michael W
authors.initials: MW
authors.lastname: Konstan
authors.forename: Janice
authors.initials: J
authors.lastname: Hunter
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Berclaz
authors.forename: Lois
authors.initials: L
authors.lastname: Brass
authors.forename: Pamela L
authors.initials: PL
authors.lastname: Zeitlin
authors.forename: Keith
authors.initials: K
authors.lastname: Hammond
authors.forename: Zoe
authors.initials: Z
authors.lastname: Davies
authors.forename: Carla
authors.initials: C
authors.lastname: Foy
authors.forename: Peadar G
authors.initials: PG
authors.lastname: Noone
authors.forename: Michael R
authors.initials: MR
authors.lastname: Knowles
mesh_terms: D000328:Adult; D002985:Clinical Protocols; D002986:Clinical Trials as Topic; D003550:Cystic Fibrosis / Q000175:diagnosis*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D017136:Ion Transport; D008297:Male; D008564:Membrane Potentials; D009297:Nasal Mucosa / Q000503:physiopathology*; D017063:Outcome Assessment, Health Care; D011933:Reagent Kits, Diagnostic; D012965:Sodium Chloride / Q000378:metabolism*
chemical_list: D011933:Reagent Kits, Diagnostic; D012965:Sodium Chloride