Relationship between exhaled nitric oxide and the frequency of severe acute exacerbation of COPD: 3-year follow-up

In a recent trial we have assessed fractional exhaled nitric oxide (FENO) in a cohort of patients with an acute exacerbation of chronic obstructive pulmonary disease (COPD). In the current study we have retrospectively investigated the frequency of severe hospitalization-associated exacerbations in the same cohort over 3 years after the initial FENO measurement. A total of 58 COPD patients were enrolled and allocated either into the low (< 27 ppb) or the high (≥ 27 ppb) FENO group depending on their FENO level at exacerbation. Beside the annual rate of exacerbations, sputum culture results and the frequency of antibiotic treatments were also analyzed during the follow-up. Both the number of exacerbations per patient-year and the hospitalization days due to exacerbations were significantly increased in patients from the low FENO group compared to those from the high FENO group. Sputum samples derived from patients in the low FENO group were more frequently indicative of a bacterial infection compared to those obtained from the other subgroup. Also, the frequency of antibiotic treatments was significantly increased in subjects from the low FENO group. Results of this pilot study suggest that COPD patients have diverse risks for future exacerbations depending on their FENO levels at exacerbation