title: Clinical Utility of Fractional exhaled Nitric Oxide (FeNO) as a Biomarker to Predict Severity of Disease and Response to Inhaled Corticosteroid (ICS) in Asthma Patients.
abstract: BACKGROUND
  Bronchial asthma is a common chronic inflammatory airway disease diagnosed and is based on symptomatic history and Pulmonary Function Tests (PFT). Fractional exhaled Nitric Oxide (FeNO) is exclusively a non-invasive biomarker of on-going eosinophilic airway inflammation which remains unpredictable only with PFTs. FeNO measurement is recommended in predicting asthma severity and Inhaled Corticosteroid (ICS) response but further research is required to understand its clinical utility and agreement with current recommendations in a specific population.
  
  
  OBJECTIVE
  To estimate FeNO levels in Tamilian patients with mild-to-moderate persistent asthma and to correlate with disease severity and ICS response.
  
  
  METHODS
  The study was a prospective cohort with a single group of 102 persistent asthma patients under standard ICS regimen for 8 weeks (follow-up period). PFT and FeNO were measured using portable spirometry and chemiluminescence based exhaled breath analyser, at baseline and during follow-up visits. Based on PFT and FeNO parameters, the study population was sub-grouped with respect to asthma severity (as mild, moderate and moderately severe), FeNO cut-off (> or < 50ppb) and ICS response classification (good vs poor ICS responders).
  
  
  RESULTS
  Significant decrease in mean FeNO levels were found in mild, moderate and moderately severe asthmatic groups following ICS treatment (90.15±27.36, 75.74±31.98 and 77.18±32.79 ppb) compared to similar baseline FeNO levels (103.03±34.08, 91.38±37.60 and 97.90±43.84 ppb) in all the above groups. Similarly, significant decrease in mean FeNO levels was found - FeNO>50ppb, good and poor ICS responders groups, in post- ICS treatment (89.63±24.04, 77.90±31.12 and 86.49±32.57 ppb) compared to baseline levels (110.183±1.23, 97.12±42.04 and 99.68±34.71 ppb).
  
  
  CONCLUSIONS
  The observed baseline FeNO values in all groups as stated above did not show significant difference to differentiate asthma severity or ICS responders groups. The present study results do not support the predictive association of baseline FeNO levels with asthma severity and future ICS response, but the decrements in FeNO levels on ICS treatment, supports its clinical utility in monitoring of ongoing airway inflammation and understanding treatment response rate.
authors.affiliation: Ph.D Scholar, Department of Pharmacology, JIPMER , Puducherry, India .
authors.forename: Revathy
authors.initials: R
authors.lastname: Neelamegan
authors.affiliation: Professor and Head, Department of Pulmonary Medicine, JIPMER , Puducherry, India .
authors.forename: Vinodkumar
authors.initials: V
authors.lastname: Saka
authors.affiliation: Associate Professor, Department of Medicine, JIPMER , Puducherry, India .
authors.forename: Kadhiravan
authors.initials: K
authors.lastname: Tamilarasu
authors.affiliation: Associate Professor, Department of Pulmonary Medicine, JIPMER , Puducherry, India .
authors.forename: Manju
authors.initials: M
authors.lastname: Rajaram
authors.affiliation: Assistant Professor, Department of Clinical Pharmacology, JIPMER , Puducherry, India .
authors.forename: Sandhiya
authors.initials: S
authors.lastname: Selvarajan
authors.affiliation: Director, CIDRF, MGMCRI, Puducherry and Retd. Senior Professor and Head, Department of Clinical Pharmacology, JIPMER , Puducherry, India .
authors.forename: Adithan
authors.initials: A
authors.lastname: Chandrasekaran
keywords: Bronchial asthma; Mild-to-moderate persistent asthma; Tamilian