Characterization of airway inflammation in patients with COPD using fractional exhaled nitric oxide levels: a pilot...

To characterize fractional exhaled nitric oxide (FeNO) levels that may be indicative of Th2-mediated airway inflammation in patients with chronic obstructive pulmonary disease (COPD).

This single-visit, outpatient study was conducted in 200 patients aged 40 years and older with COPD. All patients underwent spirometry and FeNO testing. COPD severity was classified according to the Global initiative for chronic Obstructive Lung Disease (GOLD) 2010 guidelines.

Patients who participated in the study had a mean age of 63.9 ± 11.3 years and a mean smoking history of 46 ± 29 pack years. Patients had a mean forced expiratory volume in 1 second % predicted of 53.9% ± 22.1%. The percentage of patients classified with COPD severity Stage I, II, III, and IV was 13%, 40%, 39%, and 8%, respectively. In addition, according to current procedural terminology codes, 32% of patients were classified as mixed COPD/asthma, 26% as COPD/emphysema, and 42% as all other codes. The mean FeNO level for all patients was 15.3 ± 17.2 parts per billion (ppb). Overall, 89% of patients had a FeNO <25 ppb, 8% had a FeNO 25-50 ppb, and 3% had a FeNO >50 ppb. The percentages of patients with FeNO in the intermediate or high ranges of FeNO were greatest among patients with mixed COPD/asthma (intermediate, 11.5%; high, 6.6%) compared with COPD/emphysema (intermediate, 8%; high, 0) and all other codes (intermediate, 6.3%; high, 1.3%).

Increases in FeNO were identified in a subset of patients with COPD, particularly in those previously diagnosed with both COPD and asthma. Since FeNO is useful for identifying patients with airway inflammation who will have a beneficial response to treatment with an inhaled corticosteroid, these data may have important implications for the management of COPD patients.