Standardized procedure for measurement of nasal potential difference: an outcome measure in multicenter cystic fibrosis clinical trials.
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.
Standaert
Thomas A
TA
University of Washington, Seattle, Washington, USA. thomas_standaert@chiron.com
Boitano
Louis
L
Emerson
Julia
J
Milgram
Laura J H
LJ
Konstan
Michael W
MW
Hunter
Janice
J
Berclaz
Pierre-Yves
PY
Brass
Lois
L
Zeitlin
Pamela L
PL
Hammond
Keith
K
Davies
Zoe
Z
Foy
Carla
C
Noone
Peadar G
PG
Knowles
Michael R
MR
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*
D011933:Reagent Kits, Diagnostic; D012965:Sodium Chloride