Correlation of exhaled nitric oxide, nasal nitric oxide and atopic status: A cross-sectional study in bronchial asthma and allergic rhinitis.

OBJECTIVE: Exhaled nitric oxide (FENO) and nasal nitric oxide (n NO) measurement is an area of ongoing research in the study of airway inflammation. The atopic status is known to influence the levels of FENO and n NO. This study was undertaken to study the relationship between nitric oxide measurements in bronchial asthma and allergic rhinitis along with their correlation with atopic profile of Indian population.

MATERIALS AND METHODS: Ninety subjects were recruited for the study comprising of 25 each of bronchial asthma (BA), allergic rhinitis (AR), bronchial asthma with allergic rhinitis (BA-AR) and 15 healthy controls. These were assessed for atopy and exhaled breath analysis of nitric oxide. The measurements of FENO and n NO levels were done using NIOX chemiluminescence analyzer. Atopy was assessed by skin prick testing (SPT) against 58 common aero-allergens and subjects with ≥1 positive SPT were labeled as atopic.

RESULTS: The BA-AR and BA groups had higher FENO levels in comparison to the control (P < 0.05) and AR group (P < 0.05). The AR and BA-AR groups had higher n NO levels compared to the control group (P < 0.05) and BA group (P < 0.05). The increasing FENO levels significantly correlated with the increase in the number of allergen sensitization in patients suffering from BA-AR (P < 0.05). However, the BA group showed a weaker positive correlation (P = 0.07).

CONCLUSION: FENO is a non-invasive marker of airway inflammation. Also, FENO levels correlate with presence and degree of atopy in BA and AR. Simultaneously, n NO could be a surrogate marker of rhinitis.