ASTHMA AND IMMUNOGLOBULIN-E ANTIBODIES AFTER RESPIRATORY SYNCYTIAL VIRUS BRONCHIOLITIS - A PROSPECTIVE COHORT STUDY WITH MATCHED CONTROLS

Objective. To study the occurrence of bronchial obstructive symptoms a nd immunoglobulin (Ig) E antibodies after respiratory syncytial virus (RSV) bronchiolitis in infancy. Previous studies of this subject have mostly been retrospective or without controls, or the controls have no t been followed prospectively. Design. This was a prospective cohort s tudy with matched controls. Participants. Forty-seven infants had expe rienced RSV bronchiolitis severe enough to cause hospitalization at a mean age of 3 1/2 months. For each child with RSV infection, two contr ols were acquired from the local Child Health Center and matched for d ate of birth, sex, and residence. Only one control was obtained for on e RSV child, and the control group thus contained 93 children. Methods . All the children underwent two follow-up examinations, the first one at a mean age of 1 year and the second at a mean age of 3 years. At t he first follow-up, a skin-prick test against egg white was performed, and serum IgG antibodies against RSV were measured. At the second fol low-up, serum IgE antibodies were measured using screening tests for c ommon food and inhalant antibodies, and skin-prick tests against egg w hite, cat, birch, and mite allergen were performed. Hereditary and env ironmental factors (passive smoking, indoor furred animals) and durati on of breast-feeding were recorded. Results. At the first follow-up, 8 9% in the RSV group and 27% in the control group had IgG antibodies ag ainst RSV (P < .001). At the second follow-up, asthma, defined as thre e episodes of bronchial obstruction verified by a physician, was found in 11 of 47 children (23%) in the RSV group and in 1 of 93 children ( 1%) in the control group (P < .001). A positive test for IgE antibodie s was noted in 14 of 44 (32%) RSV children and in 8 of 92 (9%) childre n in the control group (P = .002). An analysis of risk factors for the development of asthma and IgE antibodies on the whole group of 140 ch ildren showed that RSV bronchiolitis was the most important risk facto r, and a family history of atopy or asthma further increased the risk. Conclusions. Respiratory syncytial virus bronchiolitis during the fir st year of life apparently is an important risk factor for the develop ment of asthma and sensitization to common allergens during the subseq uent 2 years, particularly in children with heredity for atopy/asthma.