Respiratory Syncytial Virus Prevention and Asthma in Preterm Infants
Infection with respiratory syncytial virus in preterm infants has been associated with subsequent wheeze and asthma.
According to research published in Lancet Respiratory Medicine, respiratory syncytial virus (RSV) prevention in healthy preterm infants did not significantly affect current asthma or lung function at age 6 years.
Previously, RSV infection has been associated with subsequent wheeze and asthma. Follow-up to age 6 years was conducted in a double-blind, randomized, placebo-controlled trial that initially reported a causal relationship between prevention of RSV infection during infancy and reduced frequency of subsequent wheeze in infants born at 32 to 35 weeks of gestation.
A total of 395 preterm infants were randomly assigned to receive either palivizumab for RSV immunoprophylaxis or placebo during the RSV season of their first year of life and completed single, assessor-blind follow-up until age 6 years. The primary outcomes of parent-reported current asthma and forced expiratory volume in 0.5 seconds (FEV0.5) were then assessed (ISRCTN registry identifier: ISRCTN73641710).
Parent-reported current asthma was identified in 14.1% of children in the RSV prevention group and 24.0% in the placebo group (absolute risk reduction, 9.9%; 95% CI, 2.2-17.6). FEV0.5 percentage predicted values were 89.1% (standard deviation, 10.6) for the treatment group and 90.1% (standard deviation, 11.1) for the placebo group, with a mean difference of 1.0 (95% CI, −1.3 to 3.3). The proportion of children with current physician-diagnosed asthma was similar between both groups, at 10.3% with treatment vs 9.9% with placebo (absolute risk reduction, −0.4 [95% CI, −6.5 to 5.8]).
Reporting bias by parents may exist, however, as follow-up was single blinded after the first year of life. Also, the study only included otherwise healthy preterm infants in high-income settings; therefore, results may be limited and not generalizable. Several other limitations, such as a lack of power to detect small but clinically relevant effects of RSV prevention on different asthma phenotypes, the timing of lung function tests, missing lung function data, and an underestimation of the prevalence of current physician-diagnosed asthma, were also noted.
The investigators, however, still conclude "that RSV prevention in otherwise healthy preterm infants reduced the risk of parent-reported asthma at age 6 years," and at that point there were no differences in physician-diagnosed asthma in the past year or in lung function. Future work is still needed to determine whether RSV prevention is related to asthma risk at school age and among the general population.
Scheltema NM, Nibbelke EE, Pouw J, et al. Respiratory syncytial virus prevention and asthma in healthy preterm infants: a randomised controlled trial. Lancet Respir Med. 2018;6(4):257-264.