Asthma is a common chronic disease of childhood in developed countries causing significant burden on public health. Rhinovirus is one of the most commonly identified triggers for wheezing episodes in preschool-aged children. In this study, researchers identified characteristics of children with preschool asthma associated with susceptibility to rhinovirus infections. The authors also investigated whether rhinovirus infections were associated with a more acute clinical course of asthma exacerbation and if rhinovirus infections were associated with a more compromised 12-month asthma course.

A total of 130 children aged 4 to 6 years and who have a gestational age of at least 36 weeks. They had to have a diagnosis of mild-to-moderate persistent asthma by using Global Initiative for Asthma (GINA) criteria within the last 2 years. Patients were recruited from 5 centers in Europe. Subjects had to be asymptomatic for at least 4 to 6 weeks at baseline. Exclusion criteria included severe persistent asthma, concurrent immunotherapy treatment, and nonatopic chronic disease.

A standardized questionnaire on symptoms of asthma, rhinitis, eczema, infections, immunizations, environmental factors, and family history was completed at study entry. Baseline blood tests and nasopharyngeal swab samples were obtained. Daily medication and symptom diary was recorded. Subjects had 6-month follow-up visits for 2 years to review symptoms of asthma and rhinitis and collect nasopharyngeal samples. Guardians contacted the study center if subjects developed signs of a respiratory tract infection, had an exacerbation of asthma, had a noted decrease in forced expiratory volume in 1 second of >15% or peak flow of >30%, or had increase in symptom scores on diary of ≥4. A clinic visit was then scheduled to obtain a nasopharyngeal sample to identify respiratory pathogens.

Among 130 study subjects, 62% were boys, 55% had aeroallergen sensitization, 38% had active atopic dermatitis, and 38% had vitamin D supplementation. A total of 59% had mild persistent asthma, 25% intermittent asthma, and 83% had peak expiratory flows in the normal range. Of 571 visits, 54% were positive for any virus, and rhinovirus was detected in 39% of visits. Patient characteristics were only assessed with rhinovirus because of the low number of other respiratory viruses. The use of supplemental vitamin D was inversely associated with rhinovirus infection (P < .05). Rhinovirus was associated with more acute illness, including prolonged runny nose, severe night cough, and more sleep disturbance (all P < .05). Rhinovirus infection was also analyzed for its impact on asthma activity for the following year. Rhinovirus infection was associated with an increase in asthma activity, with more night awakenings and more days of exercise triggered symptoms (P < .05). Increased rhinitis activity was also noted in the 12-months follow-up.

Rhinovirus infection has both acute and long-term impact on preschool asthma stability. Vitamin D supplementation appears to modify rhinovirus infection and may have a protective effect against infection.

Rhinovirus infection has been a well-known trigger for asthma exacerbation, and the findings in this study are not surprising. Increasing asthma severity was noted for acute rhinovirus infection as well as for the 12-month period after rhinovirus infection. If vitamin D supplementation is truly protective against rhinovirus infection, than it may also have an impact on long-term control of childhood asthma. Controlled trials are required to confirm this prospective observation.