By how much can exhaled nitric oxide vary without a change in clinical status?

Fielding, Shona, Pijnenburg, Marielle, De Jongste, Johan, Katy, Pike, Roberts, Graham, Petsky, Helen, Chang, Anne, Fritsch, Maria, Frischer, Thomas, Szefler, Stanley, Gergen, Peter, Vermeulen, Francoise, Vael, Robin and Turner, Stephen (2017) By how much can exhaled nitric oxide vary without a change in clinical status? European Respiratory Journal, 50 (Suppl61), [PA4497]. (doi:10.1183/1393003.congress-2017.PA4497).

Abstract

Background: Fractional exhaled nitric oxide (FeNO) may be a useful biomarker to guide asthma treatment. A study in children without asthma and with mild asthma suggested that FeNO may vary by up to 100% over 2 months. The aim of this study was to describe the change in FeNO over a 3 month period in children with moderate asthma who remained controlled and with stable inhaled corticosteroid (ICS) treatment.

Methods: Data from 7 clinical trials were pooled. Each trial was broken down into three-month intervals. Individuals whose asthma was controlled and with stable ICS treatment over a particular 3-month interval were identified. The absolute and relative change in FeNO over this interval was described.

Results: Data were available on 1115 children (58% male, mean age 12.6 years). FeNO values were similar in “FeNO” and “standard treatment” arms of the trials. There were 228 eligible children in the first three-month interval, 209 in the second, 294 in the third and 296 in the fourth interval. The median (interquartile range, IQR) change in FeNO during the first 3 months was +2 parts per billion, ppb (-6, +15) and values for the successive periods were +1 (-13, +10), 0 (-8, +10) and +1 (-6, +10). The median percentage change in FeNO (IQR) for the first 3 months was +10 (-28, 79) and for the next three periods were +2 (-35, 70), +1 (-24, 50) and +5 (-21, 46).

Conclusions: FeNO values varied considerably in these eligible children. The 75th centile values suggest that absolute FeNO may rise by ≤15ppb and %FeNO by ≤80% without a change in the child’s clinical status. Similarly, the 25th centile values suggest that FeNO may fall by ≤15ppb or ≤40% without a change in clinical status.

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Contributors

Author: Graham Roberts

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