Consumption of asthma medication after RS-virus epidemic--a population based survey

It has been suggested that a respiratory syncytial virus (RSV) infection in infancy increases the likelihood of development of asthma in childhood. The RSV epidemics have a special 2-yr pattern in Finland and this allows the evaluation of the association of RSV and asthma by epidemiological means. We evaluated whether being 0-6 months of age during an RSV epidemic has an impact on the use of asthma medication later in the childhood. The consumption of asthma medication at the age of 3-16 yr and the number of those entitled to special reimbursement for asthma medication were identified for a total of 637,922 children. These subjects were grouped in cohorts according to whether they had been aged 0-6 months (exposed) or not (unexposed) during an RSV epidemic. The means of the proportions taking asthma medication and of those receiving reimbursement were calculated for each cohort. The means of the proportions in the unexposed vs. exposed cohorts were 20.5% vs. 20.3% for consumption and 4.8% vs. 4.9% for reimbursement. These differences were insignificant. In conclusion exposure to a RSV epidemic in infancy does not increase the consumption of asthma medicines at the population level.