Fractional exhaled nitrogen oxide (FeNO), asthma, respiratory symptoms and self-reported allergy among high school students in Penang, Malaysia

Background : We investigated the association between FeNO and respiratory symptoms, asthma and allergy among high school students in Penang, Malaysia. Methods : Eight high schools were randomly selected in Penang. In each school, 4 classes were randomly selected, and 20 students were randomly selected from each class. A total of 368 pupils (58%) answered the questionnaire and 348 participated in the FeNO measurements using a NIOX-MINO. FeNO was adjusted for gender, race, smoking and parental asthma or allergy. Results : The median FeNO was 17ppb (IQR 10-39), with 45% of the students reporting levels above 20 ppb. Boys had higher FeNO (p=0.001). Prevalence of respiratory symptoms in the last 12 month was 14% for wheeze, 9% for wheeze with breathlessness, 38% for daytime and 11% for night time attacks of breathlessness, while 13% ever had asthma, 11% had doctor’s diagnosed asthma and 37% had any respiratory infection in the last 3 months. Moreover, 9% reported pollen allergy, 8% cat allergy, 3% dog allergy, 5% mould allergy, 19% any food allergy/intolerance and 14% seafood allergy. FeNO was higher in students with wheeze (p=0.004), wheeze with breathlessness (p=0.04), ever asthma (p<0.001), doctor’s diagnosed asthma (p=0.002), cat allergy (p=0.01), food allergy/intolerance (p<0.001) and seafood allergy (p=0.001). Moreover, FeNO was higher in students with rhinitis symptoms in the last 3 months (p<0.001 for runny nose and p=0.002 for nasal congestion). Discussion : Median FeNO was associated with wheeze, doctor’s diagnosed asthma, rhinitis symptoms and self-reported allergy to cat and seafood.