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CFTR mutations are grouped according to disease-causing mechanism. Several studies demonstrated that patients having at least one mutation of class IV/V, present with a milder phenotype, but little is known about their relative treatment burden. We compared treatment burden between patients with two class I, II, or III mutations and patients with at least one mutation of class IV/V in the 2010 database of the Belgian CF Registry. We calculated a "Treatment Burden Index" (TBI) by assigning long term therapies to categories low, medium and high intensity, for differential weighing in the total score. There were 779 patients with two known class I/II/III mutations and 94 patients with at least one class IV/V mutation. Compared to class I/II/III, class IV/V patients had a lower median number of clinic visits (4 vs. 5; P < 0.001), a lower risk of hospitalization (24.7% vs. 50.8%; P < 0.001) and intravenous antibiotic treatment (23.5% vs. 46.0%; P < 0.001) and a lower median TBI (6 vs. 9; P < 0.001). These differences remained significant when only class IV/V patients with pancreatic insufficiency (n = 31) were considered. This study clearly demonstrates the significantly lower treatment burden in patients with CF and at least one class IV/V mutation compared to patients with two class I/II/III mutations and contributes to providing better individual counseling at time of diagnosis., (© 2015 Wiley Periodicals, Inc.)

Aim: Lung clearance index (LCI) is a sensitive marker of early lung disease in cystic fibrosis (CF). This preliminary study compares results obtained from the washin and the washout phase of the multiple breath washout in CF children and healthy controls using an early commercially available device., Methods: LCI was measured using a device measuring flow and mainstream molar mass with helium as the inert gas. Sixty-five healthy controls and 65 CF children (age range 4.6-17.9 years) were included., Results: LCI measured on the washout (LCIWO ) and on the washin (LCIWI ) were correlated in CF children (R = 0.440, P < 0.001, n = 185). LCIWO was higher than LCIWI with a mean difference of 1.08 (95% limits of agreement -2.11 to 4.27, n = 185) in CF children and 0.26 (95% LA -3.2 to 3.72, n = 185) in controls. Within-test repeatability criteria were met in 107/130 WO and 93/130 WI (P = 0.034), In 81 children, LCIWI and LCIWO were obtained. LCIWI was higher in CF patients than in controls (7.72 vs. 6.55, P < 0.001), as was LCIWO (8.49 vs. 7.13, P < 0.001). In 34 CF patients with normal FEV1 , LCIWI only was abnormal in five, LCIWO only in five and both were abnormal in three. One of seven CF patients with abnormal FEV1 had normal LCIWI and LCIWO ., Conclusion: In CF patients, discordances between abnormal LCIWI and LCIWO were observed. LCIWI and LCIWO were only weakly correlated. This likely resulted from technical factors as the use of mainstream molar mass signal, a temperature model validated for infants only and absence of CO2 correction., (© 2013 Wiley Periodicals, Inc.)

Aim: Measurement of nasal potential difference (NPD) is increasingly used as diagnostic test for cystic fibrosis (CF) and for in vivo evaluation of treatments aimed at correcting the defective function of the cystic fibrosis transmembrane regulator (CFTR) protein. Several methods are used to measure NPD. This study explores the influence of the site of measurement and compares NPD results obtained on the nasal floor and under the inferior turbinate., Methods: NPD was measured in 34 CF, 26 heterozygote, and 61 control subjects. In every subject, measurements were taken simultaneously under the inferior turbinate in one nostril, and on the nasal floor in the other nostril. Criteria for interpretable tracings were predefined. Repeat measurements were done in 57 persons., Results: More interpretable tracings were obtained under the turbinate (120/124) than on the nasal floor (109/124), P = 0.015. Within each subject group, mean values obtained were similar for maximal basal potential, response to amiloride, and total chloride response. Both techniques discriminate well between CF and controls. Repeatability was similar with both methods: mean differences between two measurements approximated zero for most values. Also after correction for different number of interpretable tracings, simulation of sample size calculation for use in CFTR corrective trials was slightly in favor of measurements obtained on the nasal floor., Conclusion: NPD measurements under the inferior turbinate and on the nasal floor have similar discriminative power for diagnostic use. Measurements under the turbinate result in a slightly higher proportion of interpretable tracings but sample size calculation slightly favors the nasal floor method., (Copyright © 2011 Wiley-Liss, Inc.)

Exhaled NO (ENO) has been studied as a noninvasive marker of airway inflammation, and has been shown to be elevated in asthma patients. The aim of this study was to investigate whether ENO measurements differ significantly between groups of asthmatic children with different disease control and to compare ENO measurements with the clinical assessment of asthma control. Seventy-three children between 5-18 years old with a diagnosis of asthma were recruited. ENO was measured online during a slow vital capacity maneuver. The mean of three plateau NO levels was used for analysis. Baseline and postbronchodilator spirometry were performed. The assessment of disease control was based on the frequency of use of beta2-agonists, occurrence of day- and nighttime asthma symptoms, and spirometry results. Twenty-one children (group 1) had good asthma control. In 31 patients (group 2), asthma control was acceptable. In 21 patients (group 3), asthma was insufficiently controlled. ENO levels were (median (quartiles)): group 1, 11 ppb (9-21); group 2, 15 ppb (11-26); and group 3, 28 ppb (19-33). Measurements were significantly different between all three groups (P = 0.009, Kruskal-Wallis), between groups 1 and 3 (P = 0.01, Mann-Whitney U test), and between groups 2 and 3 (P = 0.01, Mann-Whitney-U test). The same was true for reversibility testing. We found significantly different ENO levels between a group of pediatric asthma patients with insufficient and good/sufficient control, as defined by clinical assessment. These results suggest that ENO measurements may be useful for monitoring asthma patients., (Copyright 2003 Wiley-Liss, Inc.)