Prediction of asthma in symptomatic preschool children using exhaled nitric oxide, Rint and specific IgE

Rationale For clinicians it remains very difficult to predict whether preschool children with symptoms suggestive of asthma will develop asthma in later childhood. Objective To investigate whether measurement of fraction of exhaled nitric oxide (FE(NO)), interrupter resistance (Rint) or specific immunoglobulin E (IgE) in 4-year-old children with suggestive symptoms can predict asthma symptoms up to age 8 years. Methods Children were recruited from the PIAMA birth cohort. All children with symptoms suggestive of asthma at age 3 or 4 years, who were invited for medical examination at age 4 (n=848), were eligible. Associations of FE(NO) (n=308), Rint (n=482) and specific IgE (n=380) at 4 years with wheezing and asthma at the ages of 5-8 years were assessed using repeated measurement analyses. The added predictive value of these objective tests was then investigated by including parameters for clinical history in the model. Results FE(NO) and specific IgE measured at 4 years were associated with wheezing and asthma at 8 years. Both tests also remained significant predictors after mutual adjustment and adjustment for clinical history: OR on wheezing at 8 years for FE(NO) ((10)log-scale, per IQR) 1.6 (95% CI 1.1 to 2.2) and for specific IgE 2.8 (95% CI 1.9 to 4.1). Rint was significantly associated with wheezing at age 6, but not at 7 and 8 years. Conclusions In preschool children with symptoms suggestive of asthma, both FE(NO) and specific IgE measured at age 4, but not Rint, improved the prediction of asthma symptoms until the age of 8 years, independent of clinical history.