Role of fractional exhaled nitric oxide in patients with sickle cell disease

Patients with sickle cell disease exhibit different patterns in pulmonary function tests. In particular, there is little evidence on the fractional exhaled nitric oxide (FeNO) test, and its value ranges and its interpretation in these patients have been under debate in recent years.

We conduced a cross-sectional, observational and descriptive study between November 2021 and January 2023 including patients aged 6-18 years with sickle cell disease able to perform the FeNO test. We applied the GLI-2012 reference values and the ERS/ATS standards. We defined statistical significance as P < 0.05.

The sample included 43 patients with a median age of 12 years (IQR, 10-15). We did not find an association between significantly elevated FeNO (≥25 ppb) and the diagnosis of asthma (P = 0.37), an obstructive pattern in spirometry (P = 0.67), a positive bronchodilator test (P = 0.53), clinical bronchial hyperreactivity in the context of cold or flu-like symptoms (P = 0.48), cough with exercise (P = 0.42) or nocturnal cough (P = 1.0), but found an association with peripheral eosinophilia (P < 0.01).

We found no association between FeNO values and the classic features of asthma (clinical or spirometric) in patients with sickle cell disease. Therefore, airway inflammation mechanisms are probably different in these patients.