Exhaled nitric oxide as a marker of asthma control in smoking patients

Exhaled nitric oxide fraction (F(eNO)), which is a reliable marker of eosinophilic airway inflammation, is partially suppressed by tobacco smoking. Consequently, its potential as a biomarker in asthma management has never been evaluated in smoking patients. In the present study, the authors tested the validity of F(eNO) to predict asthma control in this population. F(eNO) and the Asthma Control Questionnaire (ACQ) were recorded at least once in 411 nonsmoking (345 with at least two visits) and 59 smoking (51 with at least two visits) asthma patients. Despite similar mean ACQ scores (1.5 versus 1.7), F(eNO) was reduced in smoking asthmatics (18.1 ppb versus 33.7 ppb). A decrease in F(eNO) of