Lung function trajectories and bronchial hyperresponsiveness during childhood following severe RSV bronchiolitis in infancy

BACKGROUND

Children with severe respiratory syncytial virus (RSV) bronchiolitis in infancy have increased risks of asthma and reduced lung function in later life. There are limited studies on the longitudinal changes of lung function and bronchial hyperreactivity from early to late childhood in infants hospitalized for RSV bronchiolitis.

METHODS

In a prospective cohort of 206 children with their first episode of RSV-confirmed bronchiolitis in the first year of life, 122 had spirometry performed at least twice between 5-16 years of age. Methacholine bronchoprovocation was available in 127 and 79 children at 7 and 12 years of age, respectively. Longitudinal changes in FEV₁ , FVC, and FEV₁ /FVC z-scores and methacholine PC₂₀ were analyzed.

RESULTS

55% of the study cohort (N = 122) were male, and 55% were Caucasian. During follow-up, longitudinal changes in z-scores for pre- and post-bronchodilator FEV₁ (P < .0001) FVC (P < .0001) and FEV₁ /FVC (P < .0001 for pre- and 0.007 for post-bronchodilator) from age 5 to 10-16 years were observed. Declined lung function in late childhood was significantly associated with gender, physician diagnosis of asthma, and allergic sensitization. PC₂₀ geometric mean increased from 0.28 mg/mL at 7 years to 0.53 mg/mL at 12 years of age, and the frequency of abnormal bronchial hyperreactivity decreased from 96% to 78% (P = .0003).

CONCLUSIONS

Following severe RSV bronchiolitis, there appear to be significant longitudinal changes in pre- and post-bronchodilator lung function during childhood. The study has several limitations including significant dropouts and the lack of a control group and post-bronchodilator measurements. Bronchial hyperreactivity is common in children following severe RSV bronchiolitis; however, it appears to decrease as they enter late childhood.

Vitamin D Levels Are Unrelated to the Severity of Respiratory Syncytial Virus Bronchiolitis Among Hospitalized Infants

BACKGROUND

Vitamin D deficiency at birth has been reported as a risk factor for respiratory syncytial virus (RSV) lower respiratory tract infection during the first year of life. Limited data are available on whether an infant's vitamin D status is associated with the severity of acute RSV bronchiolitis.

METHODS

Infants < 1 year of age and hospitalized with their first episode of RSV bronchiolitis were enrolled into the RSV Bronchiolitis in Early Life II cohort. We investigated the relationships between vitamin D status at enrollment and the following indicators of bronchiolitis severity: duration of hospitalization, lowest oxygen saturation measured during hospitalization, and bronchiolitis severity score.

RESULTS

Among the 145 enrolled infants, the median (quartile 1 [Q1], Q3) serum 25-OH-VitD level was 36.8 (29.8, 42.3) ng/mL, with 14 infants (9.7%) having deficient serum vitamin D levels (25-OH-VitD <20 ng/mL). Vitamin D-deficient infants were younger than infants with 25-OH-VitD ≥ 20 ng/mL (2.8 vs 4.5 months, respectively; P = .04) and were less likely to consume infant's formula (42.9% vs 87.0%, respectively; P < .01). The following indicators of acute bronchiolitis severity did not differ between infants who were vitamin D-deficient and nondeficient: duration of hospitalization (P = .53), lowest oxygen saturation (P = .45), and bronchiolitis severity score (P = .97), even after adjusting for age, and for infant's formula consumption.

CONCLUSIONS

Among this cohort of infants that were hospitalized for RSV bronchiolitis, vitamin D status at the time of bronchiolitis was not associated with indicators of acute bronchiolitis severity.

Randomized trial to evaluate azithromycin's effects on serum and upper airway IL-8 levels and recurrent wheezing in infants with respiratory syncytial virus bronchiolitis

BACKGROUND

Respiratory syncytial virus (RSV) bronchiolitis in infancy is a major risk factor for recurrent wheezing and asthma. Because azithromycin attenuated neutrophilic airway inflammation in a murine viral bronchiolitis model, demonstration of similar effects in human subjects might provide a strategy for the prevention of postbronchiolitis recurrent wheezing.

OBJECTIVES

We sought to investigate whether azithromycin treatment during RSV bronchiolitis reduces serum and nasal lavage IL-8 levels and the occurrence of postbronchiolitis recurrent wheezing.

METHOD

We performed a randomized, double-masked, placebo-controlled proof-of-concept trial in 40 otherwise healthy infants hospitalized with RSV bronchiolitis who were treated with azithromycin or placebo for 14 days. IL-8 levels were measured in nasal lavage fluid and serum on randomization, day 8, and day 15 (nasal lavage only). The occurrence of wheezing episodes was assessed monthly over the ensuing 50 weeks.

RESULTS

Compared with placebo, azithromycin treatment did not reduce serum IL-8 levels at day 8 (P = .6) but resulted in a greater decrease in nasal lavage fluid IL-8 levels by day 15 (P = .03). Twenty-two percent of azithromycin-treated participants experienced at least 3 wheezing episodes compared with 50% of participants in the placebo group (P = .07). Azithromycin treatment resulted in prolonged time to the third wheezing episode (P = .048) and in fewer days with respiratory symptoms over the subsequent year in comparison with placebo (36.7 vs 70.1 days, P = .01).

CONCLUSION

In this proof-of-concept study azithromycin treatment during RSV bronchiolitis reduced upper airway IL-8 levels, prolonged the time to the third wheezing episode, and reduced overall respiratory morbidity over the subsequent year.