Exhaled nitric oxide in a population sample of adults.

BACKGROUND The relationship between exhaled nitric oxide (FENO) and the diagnosis of asthma in the general adult population is not completely clear. OBJECTIVES To investigate the association between FENO and asthma, after controlling for atopy and rhinitis, in a general population sample of adults (mean age 43 years). METHODS The cohort of subjects was a sample of subjects who gave their consent to participate in the European Community Respiratory Health Survey II study. RESULTS Atopy, rhinitis and current asthma were positively and current smoking was negatively associated with FENO. Multivariate analysis showed that asthma had a significant predictive effect on FENO (beta = 0.53; 95% CI 0.21-0.84, p = 0.001), and the increase in FENO was significantly associated with the risk of current asthma (OR = 1.07, 95% CI 1.00-1.14) by the logistic regression model. Receiver-operator characteristic curve showed that FENO >or=18.5 ppb had the best combination of sensitivity (69.2%) and specificity (71%), with a positive predictive value of 24% and a negative predictive value of 95%, for the diagnosis of asthma. CONCLUSIONS Measuring FENO seems to be suitable as an adjunct to questionnaire in the evaluation of asthma in the general population.