Exhaled nitric oxide levels in military recruits with new onset asthma

Approximately 800 United States Air Force basic military trainees (BMTs) are diagnosed with asthma, annually, resulting in separation from the military. With training costs of approximately $10,000/person, around $8 million is lost per year. Improved methods in diagnosing asthma would be beneficial. The aim of this study was to determine the fraction of exhaled nitric oxide (FENO), a marker of airway inflammation, in a military recruit population referred for an asthma evaluation. In BMTs referred for respiratory complaints during basic training, FENO levels were determined before an asthma evaluation consisting of a history, physical, baseline spirometry, and histamine bronchoprovocation. Of 172 BMTs who had symptoms suggestive of asthma and underwent histamine bronchoprovocation, 80% were diagnosed with asthma. FENO levels were significantly higher in asthmatic patients than nonasthmatic patients (mean, 30 parts per billion [ppb] versus 19 ppb, p < 0.001; median, 21 ppb versus 17 ppb, p < 0.02). Various FENO cutoff points provided a range of sensitivity and specificity for the diagnosis of asthma. However, an optimal FENO cutoff level for asthma was not obtained. An FENO value of 10.5 ppb provided a sensitivity of 86% for the diagnosis of asthma, but specificity was only 21%. In contrast, an FENO value of 46 ppb provided 100% specificity but only 17% sensitivity. FENO levels were significantly elevated in BMTs diagnosed with asthma but the lack of an optimal cutoff level limits the test as a diagnostic tool for asthma. Additional studies are necessary to determine the value of FENO for asthma screening in a military population.