Clinical correlates of rhinovirus infection in preschool asthma.

BACKGROUND Investigation of preschool asthma is important since not all children outgrow their illness during this age. Data are scarce on the role of rhinovirus (RV) infections in this patient group. OBJECTIVES To investigate the role of RV infections in preschool asthma: (1) susceptibility factors, (2) clinical course, and (3) medium-term outcome. METHODS 130 asthmatic children aged 4 to 6 years from the multinational PreDicta cohort were prospectively followed for a 12-month period. Allergy tests and a standard health questionnaire were carried out at study entry. Respiratory virus presence in nasopharyngeal washes was studied at illness visits and at 3 scheduled visits. RESULTS At study entry, mean age of the children was 5.3 years. Of 571 visits, 54% were positive for any virus and 39% for RV. Patient characteristics were only assessed with RV infection due to low number of other viruses. The use of supplementary vitamin D was inversely associated with RV infection (P < .05). RV infection was associated with more severe course of acute illness in terms of more severe nighttime coughing, more sleep disturbances and more days with runny nose (all P < .05). RV infection was also associated with more severe disease course during the 12-month follow-up in terms of more nights with awakenings and more days of exercise-related symptoms (both P < .05). CONCLUSIONS Vitamin D supplementation may have an anti-rhinovirus effect. Both short- and medium-term outcomes suggest RV infection to be an important clinical marker of instable preschool asthma.