Fluctuation phenotyping based on daily fraction of exhaled @entity842 values in @entity748 XXXX .

@entity748 @entity32 @entity1 @entity565 @entity842
BACKGROUND: Fraction of exhaled @entity842 (Feno), a marker of airway @entity32 , has been proposed to be useful for @entity565 management, but conclusions are inconsistent. This might be due to the failure of mean statistics to characterize individual variability in Feno values, which is possibly a better indicator of @entity565 control than single measurements. OBJECTIVE: We characterized fractal fluctuations in daily Feno values over time and the relationship between Feno values and symptom scores. We investigated whether these are associated with @entity565 severity, control, and exacerbation risk. METHODS: Daily Feno values and symptom scores over 192 days in 41 atopic @entity748 @entity1 from the Childhood Asthma Respiratory Inflammatory Status Monitoring study were analyzed. Two methods of time-series analysis were used: detrended fluctuation analysis to quantify fractal patterns in fluctuations in daily Feno values (a value) and cross-correlation to quantify the strength of the relationship between daily Feno values and symptom scores. The associations of a values and cross-correlation with markers of @entity565 severity and control were assessed by means of regression analysis. RESULTS: Daily fluctuations in Feno values exhibited fractal-type long-range correlations. Those subjects receiving higher doses of inhaled corticosteroids at study entry had a significantly lower a value, corresponding to more random fluctuations in Feno values in those with greater inhaled corticosteroid need. The cross-correlation between Feno values and symptom scores was significantly higher in those subjects who had exacerbations. CONCLUSIONS: Fluctuation in Feno values and their cross-correlation to symptom scores contains information on @entity565 severity and control. Methods that quantify the complexity of @entity565 over time might assist in identifying @entity748 subjects with concordance between eosinophilic @entity32 and symptoms and thus increased exacerbation risk.
