Feasibility and interpretation of FE(NO) measurements in asthma patients in general practice.
BACKGROUND
Exhaled NO (FE(NO)) is a useful biomarker for the monitoring of asthma control and response to therapy. However, there is a lack of data on FE(NO) levels and their interpretation in Primary Care asthma population depending on their treatment and smoking habit. Besides, the majority of current FE(NO) tests have been done by stationary chemiluminescence analysers whose use is limited to research laboratories.


METHODS
FE(NO) measurements by the novel hand-held NO monitoring device (NIOX MINO) were made in 96 asthma patients (32 males, mean age 53+/-12) at five local General Practices during their scheduled 15-20 min visits for lung function assessment.


RESULTS
Success rate was 78% and the intra-subject coefficient of variation was 8.7%. Inhaled corticosteroid treatment had an overall reducing effect on the FE(NO) value (30.5 [19.8-49.8]) vs. patients not on the ICS (26.5 [19-94]) (p<0.044). FE(NO) levels in the ICS treated current or ex-smokers group of patients were still significantly above the normal values (p<0.0001). FE(NO) levels were similar in patients receiving ICS whether there were current, ex-smokers or non-smokers. The highest FE(NO) levels (94 [15.8-151]) were found in asthmatic current smokers and not receiving treatment with ICS. The most "normalised" FE(NO) levels (35.3 [13.5-35.3]) were seen in ex-smokers.


CONCLUSIONS
FE(NO) measurements performed with a new hand-held monitoring device are reproducible and feasible in General Practice in the majority of patients of different ages and asthma severities. A high percentage of patients with different severities of asthma and regardless of their treatment with ICS and current smoking habit (current and/or ex-smokers) had highly elevated FE(NO) values, suggesting that their current therapy was possibly insufficient to control the underlying degree of airway inflammation and asthma symptoms.
Torre
O
O
Section of Airway Diseases, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Olivieri
D
D
Barnes
P J
PJ
Kharitonov
S A
SA
D000328:Adult; D000368:Aged; D001249:Asthma / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests / Q000295:instrumentation; D005194:Family Practice; D005240:Feasibility Studies; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D019095:Point-of-Care Systems; D012044:Regression Analysis; D012129:Respiratory Function Tests; D012907:Smoking
D015415:Biomarkers; D005938:Glucocorticoids; D009569:Nitric Oxide