13 Mar Incorporating Nasal Nitric Oxide Cut-offs into the Diagnosis of Allergic Rhinitis in Patients with and without Asthma
Investigating the link between what is considered normal nasal nitric oxide levels and those exceeding particular cut-off figures may play an important role in assisting the diagnosis of Allergic Rhinitis. Nasal Nitric Oxide (nNO) when measured through the upper airways is considered a biomarker for present inflammation. To explore the possibility of using nNO in the diagnosis of allergic rhinitis (AR) in patients with and without asthma, we breakdown Sy Duong-Quy and colleagues’ 2017 paper, Study of nasal exhaled nitric oxide levels in diagnosis of allergic rhinitis in subjects with and without asthma. Six hundred and twenty-eight Vietnamese subjects were divided into a control, AR or AR + Asthma group based on their symptoms and pre-test objective findings. To be defined as having AR, one or more of the following criteria had to be met; nasal congestion, runny nose, nasal itching and sneezing that lasts more than four days when exposed to certain respiratory allergens (ie: dog or cat dander, pollen, fungus, dust mite or certain chemicals and irritants at work). Asthma was screened through a spirometry test where significant airway reversibility resulted, however, those currently managing with corticoid steroids were excluded from the study. Participants ranged from eleven to sixty years of age and were equal parts men and women.
Utilising a Hypair FeNO+ Device (Medisoft), nNO levels taken from each group were as follows; control (582ppb ± 161), AR (1614ppb ±629), AR + Asthma (1686ppb ±614). There was a significant difference between the control subjects and those with AR. Further analysis showed that either an increase in AR symptoms or a reduction in peak inspiratory & expiratory nasal flow reflected a significant correlating increase in nNO levels.
The authors then went on to answer the question, what is the most accurate cut-off point to use in the diagnoses of AR for each group? For those with AR alone, the cut-off point established was >799ppb for general population (Adult >799ppb, Children >775ppb) and for those with AR + Asthma, the cut-off point established was >1271ppb for general population (Adult > 990ppb, Children > 1458ppb). There was a significant difference between the cut-off points for the two groups.
This research importantly adds to a clinical setting, assisting with the diagnosis of allergic rhinitis through specific cut-off measures, in other words, what is considered ‘normal’ and ‘abnormal’. In conjunction with clinical symptoms and patient history, a treating physician is closer to determining an accurate diagnosis for their patients. How nNO as a biomarker responds to treatment was outside the scope of this paper and therefore writeup, however, the effect has been recently carried out in a research lab and will be in a future analysis. To conclude, nasal nitric oxide for the diagnosis of allergic rhinitis with or without asthma remains early days and more studies need to be conducted to confirm the presented figures above.
Link to Article: doi: 10.2147/JAA.S129047