Early detection of children at risk for developing allergy is an important challenge. Our first analyses in infants from the Pollution and Asthma Risk: an Infant Study (PARIS) birth cohort suggested that dry night cough was associated with parental-reported allergic disorders. The aim of the present study was to refine this finding by investigating the time course of dry night cough from birth to age 4 yr in relation to blood markers of atopy and allergic morbidity.Methods
Health outcomes were regularly assessed by parental self-administered questionnaires. Blood markers of atopy were measured at age 18 months. Children with similar patterns of dry night cough over the first 4 yr of life were grouped together using k-means clustering. Associations with atopy/allergy were studied using multinomial logistic regression.Results
Three trajectories of dry night cough were identified in 1869 children. Besides the never/infrequent pattern (72.4%), the transient pattern (8.8%) was composed of children who coughed in the first year and recovered by age 4 yr, while the rising pattern (18.8%) included all symptomatic children at age 4 yr, whether they were persistent or late coughers. Compared with the never/infrequent pattern, the rising pattern was significantly associated with elevated total immunoglobulin E (IgE) level (odds ratio [OR] = 1.70, 95% confidence interval [CI] = 1.21–2.39) and inhalant allergens sensitization (OR = 2.66, 95% CI = 1.26–5.61) at age 18 months, and with doctor-diagnosed allergic diseases over the first 4 yr such as hay fever (OR = 2.52, 95% CI = 1.49–4.26) and eczema (OR = 1.29, 95% CI = 1.00–1.66).Conclusions
This study provides evidence that persistent/late dry night cough may indicate allergy in preschool children.