Causal Direction between RSV Bronchiolitis and Asthma Studied in Monozygotic Twins.

Abstract:

ABSTRACT BACKGROUND: Respiratory syncytial virus bronchiolitis has been associated with later development of asthma, wheezing, abnormal pulmonary function and sensitization. Aim was to determine the differential effect within monozygotic twin pairs discordant for severe respiratory syncytial virus bronchiolitis in infancy on the subsequent development of asthma, pulmonary function and allergy. METHODS: 37 monozygotic twin pairs discordant for respiratory syncytial virus hospitalization in infancy (mean age 10.6 months) were compared at the mean age of 7.6 years for lung function, bronchial responsiveness, fractional of exhaled nitric oxide, asthma diagnosis, use of asthma medication, and skin prick test to common inhalant allergens. RESULTS: There were no differences within monozygotic twin pairs discordant for respiratory syncytial virus hospitalization in infancy with respect to pulmonary function, fractional exhaled nitric oxide, asthma prevalence, asthma medication use, or sensitization (p>0.1 for all comparisons). CONCLUSION: We found no differential effect from severity of RSV infection on the development of asthma and allergy in MZ twin pairs discordant for RSV hospitalization in infancy. This argues against a specific effect of the severe RSV infection in the development of asthma and allergy. Because of the small sample size this study must be considered as a hypothesis generating study.