Diagnostic accuracy of fractional exhaled nitric oxide in asthma: a systematic review and meta-analysis of prospective studies

Background: Fractional exhaled nitric oxide (FeNO) has been proposed as a non-invasive measure of airway inflammation in asthma. However, its accuracy for the diagnosis of asthma in different populations is not completely clear. The aim of this study was to investigate the accuracy of FeNO measurement for the diagnosis of asthma through a systematic review and meta-analysis of prospective studies. Methods: A systematic search current to July 2014 was performed in Pubmed, EMBASE, Medline, the Cochrane databases, CNKI, Wanfang and Weipu to find relevant studies. All prospective studies on the use of FeNO for the diagnosis of asthma were included. Results: Twenty-five studies including 3983 subjects were analyzed. The pooled sensitivity, specificity and diagnostic odds ratio (DOR) for the entire population was 72% (95% CI, 70-74%), 78% (95% CI, 76-80%) and 15.92 (95% CI, 10.70-23.68), respectively. The area under the summary receiver operating characteristic (sROC) curves revealed a receiver-operating characteristic of 0.88. In subgroup analysis, the DOR for patients using corticosteroids, as well as those for steroid-naive, non-smoking, smoking, chronic cough and allergic rhinitis patients were 4.47 (95% CI, 3.39-5.90), 21.40 (95% CI, 15.38-29.76), 19.84 (95% CI, 15.63-25.19), 5.41 (95% CI, 2.97-9.86), 35.36 (95% CI, 23.90-52.29), and 2.99 (95% CI, 0.85-10.45), respectively. Conclusion: FeNO is accurate for the diagnosis of asthma in steroid-naive or non-smoking patients, particularly in chronic cough patients.