Published online May 16, 2023. doi: 10.4253/wjge.v15.i5.407
Peer-review started: October 2, 2022
First decision: December 1, 2022
Revised: February 5, 2023
Accepted: April 4, 2023
Article in press: April 4, 2023
Published online: May 16, 2023
Eosinophilic esophagitis (EoE) is characterized by eosinophilic inflammation of esophageal mucosa and symptoms of esophageal dysfunction. To avoid the burden of multiple endoscopies and associated risks of procedures, search for a surrogate marker for esophageal inflammation has been ongoing and inconclusive till date. Previous low powered studies assessing Fractional exhaled nitric oxide (FeNO)’s utility in EoE were noted to have a trend for association. No previous studies investigated the effect of eosinophilia in stomach and duodenum on FeNO.
To identify a non-invasive marker of disease activity in EoE that could be a low-risk, low-cost alternative to endoscopic evaluation. FeNO measurements have been successfully utilized in management of eosinophilic airway inflammatory disorders such as asthma. Our study assessed FeNO as a potential biomarker to monitor esophageal eosinophilic inflammation in EoE.
Main objective of our study is to evaluate utility of FeNO in management of Pediatric EoE. Our study also analyzed if gastric and duodenal eosinophils (downstream eosinophilia) have any effect on FeNO scores.
Pediatric patients with upper gastrointestinal symptoms and suspected EoE were enrolled in this cross-sectional study. Chemiluminescence nitric oxide analyzer (NIOX MINO, Aerocrine, Inc.; Stockholm, Sweden) machine was used to obtain FeNO measurements prior to endoscopy. Clinical characteristics data for all EoE and non-EoE patients was collected. Correlation of FeNO levels with esophageal eosinophils, EoE and abnormal downstream eosinophilia in the stomach and duodenum was analyzed. A comprehensive atopy questionnaire was utilized for presence of atopy, which was controlled for in a separate logistic regression analysis to assess its effect on FeNO in EoE patients.
Higher FeNO levels were found in patients with EoE compared to the non-EoE cohort, after adjusting for atopy. FeNO levels more than 30 ppb were noted to be more specific for active esophageal inflammation. Elevated FeNO levels were also noted in patients with high gastric and duodenal eosinophils, with a trend towards significance.
Given the specificity of high FeNO levels (> 30 ppb) in prediction of histological diagnosis of EoE, a FeNO cutoff could be established for surveillance in EoE patients, particularly those with high initial FeNO levels. Cautious interpretation or perhaps a higher FeNO cut off may be needed in patients with high downstream eosinophils. FeNO may have a clinical role in management of EoE to suggest response to therapy in a subset of pediatric EoE patients. Future studies are needed to evaluate this further.
Future studies should focus on including EoE patients from the time of diagnosis, and in remission while following an individual patient’s FeNO levels over time to allow monitoring of esophageal inflammation. This could provide a precise assessment for utilization of a FeNO cutoff in prediction of esophageal eosinophilic inflammation.