Recurrent cough: natural history and significance in infancy and early childhood

We investigated the outcome for a sample of children in whom recurrent cough was reported in the preschool years to determine 1) whether they shared the characteristics attributed to cough variant asthma, and 2) the proportion who developed classical wheezy asthma at follow-up during the early school years. A cohort of children identified as having recurrent cough in the preschool period was reassessed during the early school years. Previously identified asymptomatic preschool children who remained symptom-free provided a comparison group with respect to current respiratory symptoms, lung function, bronchial reactivity to inhaled methacholine, atopic status, peak flow variability, and recorded night cough. The response rate was modest, with 41% attending the follow-up study; information on current symptoms was available from a further 16%. Ascertainment of current symptoms showed that 70 of 125 (56.0% [95% CI 47.3-64.5%]) were symptom-free at follow-up, 46 (36.8% [28.7-45.5%]) continued to have recurrent cough in the absence of colds, and 9 (7.2% [3.6-12.8%]) reported recent attacks of wheeze. When comparing the 46 children whose recurrent cough persisted from the preschool period through to follow-up with subjects from the asymptomatic comparison group, the former had significantly more night cough (50.0% vs. 16.8%; P< 0.01), were more likely to be treated (10.9% vs. 1.7%; P=0.01), or were diagnosed (26.1% vs. 5.7%; P < 0.001) as asthmatic. They also showed greater bronchial reactivity than their asymptomatic counterparts (1.23 mg/ml vs. 3.35 mg/ml; P=0.002). Atopic status and other indices of lung function were similar between groups. We conclude that there are a group of children with long-term recurrent cough who display features consistent with a diagnosis of cough variant asthma, but at 2-4 years of follow-up, few progress to develop asthma characterized by wheeze.