PT  - JOURNAL ARTICLE
AU  - K. De Boeck
AU  - L. Kent
AU  - J. Davies
AU  - N. Derichs
AU  - M. Amaral
AU  - S.M. Rowe
AU  - P. Middleton
AU  - H. de Jonge
AU  - I. Bronsveld
AU  - M. Wilschanski
AU  - P. Melotti
AU  - I. Danner-Boucher
AU  - S. Boerner
AU  - I. Fajac
AU  - K. Southern
AU  - R.A. de Nooijer
AU  - A. Bot
AU  - Y. de Rijke
AU  - E. de Wachter
AU  - T. Leal
AU  - F. Vermeulen
AU  - M.J. Hug
AU  - G. Rault
AU  - T. Nguyen-Khoa
AU  - C. Barreto
AU  - M. Proesmans
AU  - I. Sermet-Gaudelus
TI  - CFTR biomarkers: time for promotion to surrogate end-point
AID  - 10.1183/09031936.00057512
DP  - 2013 Jan 01
TA  - European Respiratory Journal
PG  - 203--216
VI  - 41
IP  - 1
4099  - http://erj.ersjournals.com/content/41/1/203.short
4100  - http://erj.ersjournals.com/content/41/1/203.full
SO  - Eur Respir J2013 Jan 01; 41
AB  - In patients with cystic fibrosis, cystic fibrosis transmembrane conductance regulator (CFTR) biomarkers, such as sweat chloride concentration and/or nasal potential difference, are used as end-points of efficacy in phase-III clinical trials with the disease modifying drugs ivacaftor (VX-770), VX809 and ataluren. The aim of this project was to review the literature on reliability, validity and responsiveness of nasal potential difference, sweat chloride and intestinal current measurement in patients with cystic fibrosis. Data on clinimetric properties were collected for each biomarker and reviewed by an international team of experts. Data on reliability, validity and responsiveness were tabulated. In addition, narrative answers to four key questions were discussed and agreed by the team of experts. The data collected demonstrated the reliability, validity and responsiveness of nasal potential difference. Fewer data were found on reliability of sweat chloride concentration; however, validity and responsiveness were demonstrated. Validity was demonstrated for intestinal current measurement, but further information is required on reliability and responsiveness. For all three end-points, normal values were collected and further research requirements were proposed. This body of work adds useful information to support the promotion of CFTR biomarkers to surrogate end-points and to guide further research in the area.